Collaborative Research on the

Improvement of Irrigation Operation and Management: Water Quality

Investigations

Final Report

Submitted to the Council ofAgriculture

Agricultural Engineering Research Center Taoyuan Irrigation Research and Development Foundation

Environment Greening Foundation and Tsao-Jiin Memorial Foundation for Research and Development

for Agriculture and Irrigation

of the Republic ofChina

August 1999

INTERNATIONAL WATER MANAGEMENT INSTITUTE

International Water Management Institute. 1999. Collaborative research on The improvement of irriga­tion operation and management: Water quality investigations. Final Report submitted to the Council of Agriculture, Agricultural Engineering Research Center, Taoyuan Irrigation Research and Development

Foundation, Environment Greening Foundation, and Tsao-Jiin Memorial Foundation for Research and Development for Agriculture and Irrigation of the Republic of China, August 1999. Colombo, Sri Lanka:

International Water Management Institute.

Please direct inquiries and comments to: SL

International Water Management Institute

PO Box 2075 Colombo Sri Lanka

1.

© IWMI, 1999. All rights reserved.

Responsibility for the contents of this publication rests with the individual authors.

The International Irrigation Management Institute, one of sixteen centers supported by the Consulta­tive Group on International Agricultural Research (CGIAR), was incorporated by an Act of Parliament

in Sri Lanka. The Act is currently under amendment to read as International Water Management Insti­tute (IWMI).

2.

Cover photograph of the Bundala National Park by Margaretha Bakker.

3.

4.

!­

If

It

d Contents I:

Summary . I

1. Case Study in Sri Lanka: Irrigation and Drainage Water Quality and Impacts of Human Activities on the Aquatic Environment in a Southeastern Part of Sri Lanka 3

Introduction 3

Materials and Method 5

Results and Discussion 5

Conclusions 16

References 17

a­2. Case Study in Mexico: Urban Wastewater Reuse for Crop Production

in the Water-Short Guanajuato River Basin, Mexico 19 nt Introduction 19 1­

Wastewater Irrigation in Mexico 21 Field Research Program 23

Methods and Materials 24

Results 26

Conclusions 29

3. Limitations of Irrigation Water Quality Guidelines from a Multiple Use Perspective 31

Introduction 31 Principles for Improved Guidelines 32

Sustainability Principle 32

Hazard Principle 34

Irrigation and Domestic Water Supply 34

Discussion ., 36

References 37

4. Case Study in Pakistan: Water Quality and Health Impacts of Domestic Use of Irrigation Water 39

Background and Rationale 39 Objectives 41

Methods 4I

Project Plan 46

Outputs and Project Beneficiaries 49

References 49

v

r .. ·····..•• ····:··r -. (> .: ' ."Of

Summary

Tn the fiscal year 1999 (from 1 July 1998 to 30 June 1999), the Council of Agriculture (COA) and the Irrigation Associations of Taiwan provided support to the research on the improve­ment of irrigation operation and management, carried out by the International Water Manage­ment Institute (IWMI)' in collaboration with the Agricultural Engineering Research Center (AERC). The COA has been supporting the collaborative research program since the fiscal year 1998, and this second year's program is in part a continuation of the first year's program with added different components. There are four main components to the program:

1. SRILANKA

Irrigation and Drainage Water Quality and Tmpacts of Human Activities on the Aquatic Environment in a Southeastern Part of Sri Lanka

IWMI has been working with the Irrigation Department in the Kirindi Oya Irrigation and Settle­ment Project (KOISP) area for many years. In 1997, the Health and Environment Program started a new project to study the nonagricultural uses of irrigation water. The environmental func­tions of water and the impact of irrigation on valuable ecosystems came up as an important issue during this research. IWMl, in collaboration with government and nongovernment or­ganizations, attempted to develop appropriate water management strategies that could improve and sustain the environment of the Bundala National Park. For development of such manage­ment strategies, identification of direct and indirect water uses and a better understanding of the cause-effect relationship between irrigation and the ecology oflagoon system are required. This report presents the progress of a component of this research that has been carried out with support from the Council ofAgriculture and the Agricultural Engineering Research Cen­ter of the Republic of Taiwan.

2. MEXICO

Urban Wastewater Reuse for Crop Production in the Water-Short Guanajuato River Basin, Mexico

As is the case with most water management practices, there are significant trade-offs associ­ated with irrigation using untreated urban sewage. From a river-basin perspective, wastewater

'The International Irrigation Management Institute, one of sixteen centers supported by the Consultative Group on International Agricultural Research (CGIAR), was incorporated by an Act of Parliament in Sri Lanka. The Act is currently under amendment to read as International Water Management Institute.

2

irrigation is an important fonn of water and nutrient reuse; however, there are important water quality, environmental, and public health considerations. This report explores the advantages and risks of urban wastewater reuse for crop production in the water-short Guanajuato river basin in west-central Mexico. Through a selective literature review, we demonstrate how com­mon this practice is in Mexico and throughout the world. Finally, we apply and validate the Interactive River Aquifer System (IRAS) water quality model and evaluate the outcome ofsev­eral alternative water management scenarios for water and soil quality in the study area.

3. WATER QUALITY GUIDELINES

Limitations of Irrigation Water Quality Guidelines from a Multiple Use Perspective

The criteria of irrigation water quality are currently provided by global and national guidelines based on the assumption that threshold values can be applied to protect crops. This approach can create problems for a largely unrecognized group of people who make use of irrigation water for nonagricultural purposes. At the same time, the increasing water scarcity will lead to the need for recycling of water in irrigated river basins, and irrigation with lower quality of water. Apart from hazards of high-pollutant levels, a sustainability criterion has to be included in the water quality guidelines to account for long-term low-level application of certain pollut­ants that can accumulate in the environment. Using the example of cadmium, it is argued that the current guidelines need to be revised and should take local factors and future develop­ments into account.

4. PAKISTAN

Water Quality and Health Impacts of Domestic Use of Irrigation Water

Irrigation water constitutes the only available source of drinking water for many people in rural areas. They either draw it directly from irrigation canals or indirectly from seepage wells. It has been documented that drinking untreated surface water is one of the main causes of diseases and deaths in many countries. But so far, irrigation water is rarely regarded as a drinking water source by policy planners and researchers and has therefore not been considered as a possible cause of diseases related to drinking water. This also means that the domestic use of irrigation water is often not taken into account when irrigation schemes are constructed or rehabilitated. However, if research could document the need for the perception of change re­garding the irrigation versus drinking water issue, and at the same time give working tools to the planners/researchers, adverse health impacts could be avoided in the future. Therefore, the overall goal of water quality study in Pakistan is aiming at preventing the water-related diseases in areas where people use irrigation water for domestic purpose.

ortantwater advantages ajuato river ehow com­validate the :omeofsev­dyarea.

Perspective

al guidelines lis approach of irrigation , will lead to er quality of .be included srtain pollut­I argued that ire develop­

er

ny people in epage wells. ~n causes of as a drinking ~sidered as a nestic use of instructed or

change re­ing tools to

r.. Therefore, ater-related

-

Case Study in Sri Lanka: Irrigation and Drainage Water Quality and Impacts

of Human Activities on the Aquatic Environment in a Southeastern Part of Sri Lanka

Report compiled by Y. Matsuno, llM! HQ, Sri Lanka

INTRODUCTION

In Sri Lanka, irrigation water is used for many purposes other than irrigating field crops. Water from reservoirs and canals is used for livestock watering, fisheries, industries, and domestic purposes like drinking, bathing, and laundering. It also contributes to sustain the environ­ment, like wildlife and wetland ecosystems (Bakker et al. 1999). The substantial environmental services of water have often been neglected in the environmental considerations in water al­location decisions, resulting in deterioration and depletion of ecosystems. This happens be­cause many of these services go unrecognized and system managers only pay attention to the services and functions the system is designed for: irrigation and, sometimes, domestic uses of water.

Water is the primary resource controlling the ecosystem in wetland areas. I Wetlands are among the earth's most productive ecosystems and directly support millions of people and provide goods and services to the world outside the wetland as well. Direct and indirect hu­man activities, especially related to irrigation development, have considerably changed wet­land ecosystems (Barbier, Acreman, and Knowler 1997). Wetlands are also threatened by the increasing water scarcity and the wetland ecosystems have to compete with irrigation for fresh­water.

The Bundala National Park is located along the south coast of Sri Lanka, 275 kilometers from Colombo (figure 1). The climate is generally hot and dry, with an annual rainfall of 1,074 mm and a mean temperature of 27°C. The total area of the park is 6,216 hectares, including 5 shallow brackish water lagoons (Maha, Koholankala, Malala, Embilikala, and Bundala) with a total surface area of 2,250 hectares. The park has important populations of water birds, el­

'In this paper the broad definition of the International Convention on Wetlands (Ramsar Convention Manual 1997) is used. Wetlands are defined as areas of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water, the depth of which at low tide does not exceed six metres. In addition, wetlands may incor­porate riparian and coastal zones adjacent to the wetlands, and islands or bodies of marine water deeper than six metres at low tide lying within the wetlands.

3

4

Figure 1. Map of Study Area.

I .5 0 1 1 )km

Lunugamwehera

Reservoir

Pannagamuwa Wewa ---+_

Bandagiriya

Tank

Ellaga/aAnicut ~~-~'-"'l1

WeerawilaWewa -----"----/

./

~,.

BUNDALANATIONAL PARK

• Newarea

Brackish waterbodies

IV Canal

/\J Drainage

':3 Parkboundary

Tissa Wewa

YodaWewa

StudyA/ea

fN D

D •

O/darea

Water bodies

ephants, turtles, and other wildlife. The brackish water lagoons serve as nurseries for shrimp, fish, and a variety of other marine organisms (Matsuno, van der Hoek, and Ranawake 1998). It was declared a sanctuary in 1969 and upgraded to the status of a National Park in 1992. Due to the existing natural values the area was listed under the International Convention of Wet­lands, the Ramsar Convention, in 1991, so far being the only one of its kind in Sri Lanka. The main reason for this establishment is that the area is regarded as an internationally important waterfowl habitat (CEA 1993).

The ecosystems of the Malala and Embilikala lagoons have been severely affected by the drainage flow from the Kirindi Oya Irrigation and Settlement Project (KOISP) and the Badagiriya Irrigation Scheme, which are located upstream of the park (figure 1). Following the implementation of the KOISP in 1987, which increased the irrigated area from 4,200 hectares to 10,450 hectares, salinity levels of the lagoons have dropped due to inflow of upstream irriga­tion water. This change in salinity levels has decreased the population of water birds as it has affected their food supply. Prawn fishing, which previously sustained several hundred fami­lies, has also been affected by this change and it has now almost disappeared from the area. This paper will concentrate on the irrigated areas of Badagiriya (850 ha), Right Bank tracts 5, 6, and 7 (1,760 ha) and three environmentally sensitive adjacent water lagoons: Malala (650

ha), drai by t

the the stan for j

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5

ha), Embilikala (430 ha), and Bundala (520 ha). The first two lagoons are most affected by the drainage water. The Bundala lagoon has its own small catchment, and is therefore not affected by the irrigation development.

Although drainage water is considered to be one of the major causes of the changes in the lagoon ecology, there is still a lack of knowledge about the impact of drainage water on the ecosystem of the park (Matsuno, van der Hoek, and Ranawake 1998). A thorough under­standing of this relation to the activities taking place in and around the lagoons is essential for planning and selecting effective conservation measures for the park. Besides, characteriza­tion of water bodies is needed to understand and assess the environmental status and pro­cess in the wetland ecosystem. This is further important for making measurement and com­parison of the various possible benefits of water and to assist as a tool in decision making on the management of the resource. Therefore, this chapter describes environmental concerns by human activities taking place around the park and also reports some results of primary moni­toring of irrigation, drainage, and lagoon water quality over the I-year period.

MATERIALS AND METHOD

To describe human activities and their impact on the environment, qualitative and quantitative information was collected from relevant government officers, NGOs, key informant interviews, and field observation. The primary and secondary data were stored in a database system and processed at the IWMI headquarters.

For water quality measurements, water samples were collected from irrigation (Lunugamvehera Reservoir) whose drainage water enters the Embilikala lagoon, and the water body of Embilikala lagoon. The samples were collected in the fourth week of every month from October 1997 to September 1998. Water and air temperatures, electrical conductivity (EC), and pH were measured at sampling sites using portable meters. Water samples were analyzed for their chemical concentrations at the National Water Supply and Drainage Board (NWSDB). The sampling procedure and analysis methods followed were those recommended by the NWSDB.

RESULTS AND DISCUSSION

The importance of the resources of the Bundala National Park is paramount for the communi­ties in the vicinity of the Park. The irrigated areas upstream of the Park provide livelihood opportunities for 3,000 farmer families. Besides the contribution to the livelihoods of the fami­lies, either in cash or subsistence, these activities have some other impacts as well.

Institutional Impact

Before Bundala attained the status of a National Park (1992) people were allowed to retain land titles. Being a National Park, Bundala has far-reaching implications. First, a National Park

6

is only state land and no private landownership is allowed. Boundaries of the Park are now under discussion in the Parliament to avoid private landholdings in the Park. Second, most of the human activities, except lagoon fishing and tourism, are prohibited by law (CEA 1993).

Despite these regulations the resources in the Park are still used for a variety of purposes and most of the people involved in these activities are local villagers who have been forced into some illegal activity through lack of land for grazing, fuel, or income (CEA 1993).

The Bundala National Park covers 5 Grama Nilidari Divisions? with a total of approxi­mately 1,100 families. The Department of Wildlife Conservation (DWLC) is responsible for the overall management of the Park and also for the enforcement of the aforementioned regula­tions. Strict enforcement of regulations is virtually impossible owing to lack of staff and trans­port (CEA 1993). During 1997, no patrolling or evidence of law enforcement was observed (Kularatne 1999). Besides a lack of enforcement from the DWLC, there was no compulsion to discontinue these illegal activities because the amounts of money fined were insignificant.

In addition to the problem of enforcement, another management problem of the Bundala

National Park is that most of the institutional authorities are defined along sectoral or geo­graphic lines that do not correspond to the range and types of environmental problems. The problems in this area cross these boundaries and authorities of a single department. Policies and decisions of one authority have an impact outside their geographical and sectoral lines. This problem becomes visible in the impact of the upstream irrigation system on the ecosys­tem of the Bundala National Park. The Irrigation Department is the responsible agency for the management of the upstream irrigation system but the protection of the Bundala National Park is not in its mandate. This shows the need to coordinate problems related to water manage­ment, preferably at basin level.

Agriculture

Within the park boundaries, agriculture itself does not appear to be an environmentally de­structive activity. The most serious threat to the Park comes from the upstream KOISP. Efforts to clear and irrigate land and settle large numbers of people close to the Bundala National Park have led to wetland degradation, mainly because of impacts resulting from a range of activities these people carry out besides farming (CEA 1993). The irrigated agriculture, up­stream of the Bundala National Park, generates important benefits. Apart from income and employment generation it contributes to food security and social consistency by decreasing the trend of migration from rural to urban areas (Bakker et al. 1999). However, irrigation deliv­

ers large quantities of freshwater to the lagoons in the Park and has significantly altered the salinity levels of the lagoon and thus changed the ecosystem of the Park. Table 1 shows the change in salinity level for the Malala lagoon following upstream irrigation development. In 1998, a comprehensive water balance study was performed in the area. For this study the drain­age flow from RB tract 5 into the Bundala National Park was measured and quantified at 68 million cubic meters (MCM). The total net inflow in the system was 478 MCM, 14 percent of which drained into the Bundala National Park (Renault, Hemakumara, and Molden 1999).

2Local level administrative unit in Sri Lanka.

rw

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od

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lfk

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---------------....,.,.... .., ..

Tahle J. Average annual salinity level, Malala lagoon.

Year Lowest Highest

85/87 10 ppt* 41 ppt

91/92 5 ppt 10 ppt

95/97 o ppt 7 ppr

Source: Kularatne 1999.

"Parts per thousand.

Another potential source of ecosystem transformation is agrochemicals used for irrigated

agriculture. At the moment, a survey is being conducted to estimate quantities and types of

fertilizer and pesticides used in RB tracts 5, 6, and 7, and in Badagiriya, which are brought into

the ecosystem of the Park through the drainage water. The excess drainage water results also

in flooding of the agricultural and grazing lands around the Park. The lagoon area has in­

creased at the cost of agricultural, grazing, and forest land. The maximum surface area of the

Malala lagoon increased from 437 hectares in 1983 to 650 hectares in 1997 (Kularatne 1999). Further, the creation of the KOlSP disrupted the livestock grazing system and wildlife habitat

by converting grazing land and forest areas to paddy land. Many elephant migratory routes

have been disrupted by farmlands and this has resulted in crop damage by elephants, leading

to the human-elephant conflict in the area.

Fisheries

Prior to the implementation of the KOlSP in 1987 and drainage inflow into the Bundala Na­

tional Park, 400 families sustained themselves with prawn fishing in the Malala and Embilikala

lagoons. At present, they have less income from fishing and people are forced to look for

other income or subsistence-generating activities, in or near the Park (lIMl 1995; M.P. Gamage

personal communication). Fishing is still continuing in these lagoons at a low intensity. Be­

sides the change in the composition of the fish species, the fishermen have observed an in­

crease in the number of fishermen, change in type of nets used (57% use prohibited small

mesh gill nets), and a decrease in fish-breeding behavior after upstream irrigation develop­

ment (Kularatne 1999). Despite these problems people continue fishing in the lagoons because

the input costs are very low when they use a canoe without an engine.

At the present level of intensity and technology, fishing in the lagoons is not a serious

environmental threat to the lagoon ecosystem. Removal of fish for human consumption may

decrease the Park's carrying capacity of fish-eating birds, but there is no evidence of this

being a problem at present (CEA 1993). The fishermen have been fishing in the lagoons for

four generations and the officials of the DWLC do not see them as a threat to the Park eco­

system. Aquacultural techniques are not allowed to be used in the lagoons, for instance, to

increase shrimp production. Table 2 shows the average fish and shrimp production over the

years for the Malala lagoon. The table indicates that the lagoon is not suitable anymore for

shrimp production but is favorable for the existence of other fish types, mainly cichlid. This is

not surprising since the acceptable salinity range for shrimp culture is between 5 and 35 ppt,

with an optimum range of 15 to 25 ppt while the current maximum salinity level of the lagoon

is 7 ppt.

7

68

:

8

Table 2. Average fish and shrimp production per year (in kglha). stre:

Before 1987 91-92 95~97 (ibit

Average fish

Average shrimp

Not available

15.38-30.77

120

5.2-15

60

No shrimp

foot

Fun

production

Fuelwood Collectipn

The main source of energy for cooking in the area is fuelwood. It is collected by the local population for domestic as well as commercial purposes in the forest areas around the lagoons. They sell it to both shell burners who use it in their shell kilns and to people from the nearby towns (Kularatne 1999).

The forests around the lagoon are critically important to the area's ecosystem (CEA 1993). Fuelwood collection is an environment damaging activity that leads to the propagation of undesirable species of plants. For this reason, cutting of trees is banned within the bound­aries of the Park but it is still practiced (ibid.). Collection of dead branches is also prohibited but this activity continues to take place. The demand for fuelwood has increased due to irri­gation development and the human settlement close to the Park. Since this is an illegal activ­ity quantitative data are lacking. However, it is clear that fuelwood collection is of high impor­tance to the livelihoods of the families around the Park.

Livestock

Livestock, mainly buffalo and cattle, is an important subsistence and income-generating activ­ity in the study area. The animals are mainly reared for milk, and to produce curd for which the area is well known. The livestock productivity is quite low because a large part of the herd is not used for milk production but as a capital asset. The ownership of livestock is recognized as a status symbol and the size of the herd is more important than the quality of the herd. Although it is illegal to allow domesticated animals to graze within the Park boundaries it happens quite often. Some large herds are owned by people outside the study area.

Before the start of the KOISP, livestock was one of the major livelihood activities of the communities in the study area. Lack of grazing land is now a major constraint in keeping live­stock. In the planning of the KOISP, nobody took into account the livestock and their need for pasture area and the previous grazing grounds turned into irrigated rice fields. Livestock owners are to be blamed as well for the loss of grazing grounds under the KOISP because when the organizations sought data of the number of animals they owned, they did not pro­vide the correct figures (Kularatne 1999).

The numbers of domestic cattle and buffalo that use the resources of the National Park vary according to the yala (dry) and maha (wet) seasons. During yala, livestock is mostly found along the northern boundary of the Park and the adjacent fallow rice fields in tracts 5, 6, and 7 and Badagiriya. In yala 1997,4,000 domestic cattle and 1,700 buffalo were counted in this area (Bopitiya, Dayawansa, and Kotagama 1998). Livestock moves into the Park during maha when the rice fields are cultivated. The continuous supply of freshwater from the up-

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stream irrigation systems encourage even more livestock to come to the Bundala National Park (ibid.). They compete directly with the wild animals, like the elephant and the spotted deer, for food in the park. All this leads to overgrazing of the area and to serious soil degradation. Further, dung and urine of livestock enrich the lagoon system and cause eutrophication.

Medicinal Plant Collection

So far, not much is known about medicinal plant collection and the role of medicinal plants in the livelihoods Of the communities. A recent countrywide project to safeguard the wealth of medicinal plants, funded by the World Bank and the Global Environmental Facility, encoun­tered a lot of opposition from local environmentalists. They objected to the collection of tra­ditional knowledge without proper benefits to the local population (IPS 1999).

Salt Farming

Since the Bundala lagoon has its own small catchment it has not been affected by irrigation development and therefore the water has maintained its natural salinity level. Though salt production is not directly linked to or affected by freshwater inflow we took it into account because it is an important employment-generating activity and is thus important to the liveli­hoods of the villagers. We also considered salt farming so as not to take the risk of overlook­ing an important ecological relationship that is unknown at the moment. The Salt Corporation operates 100 hectares of the Bundala Lagoon despite the fact that human activities and pri­vate landownership are not allowed within the Park boundaries. In 1978, the Salt Corporation became operative, first, under the ownership of the government and, subsequently, of a pri­vate company. As the salt farm creates a lot of employment for the villagers, the DWLC allows the salt farm to continue its operations but it cannot extend its area further than the existing 100 hectares.

Salt production is seasonal and limited to periods of low rainfall (July-October and Feb­ruary-May). The Bundala saltern produces 15,000 tonnes/year. In total, 70 permanent employ­ees and 43 casual, and 250 seasonal laborers are employed in the salt farm. They all travel within a radius of 15 kilometers. The benefits of salt production are given in table 3.

The water inlet pond, where water from the ocean is pumped into the salt pans, is an important feeding place for birds. The water and salinity levels in this pond are controlled and this provides a valuable feeding ground, especially for flamingos and small wading birds. Since the salinity of the Embilikala and Malala lagoons is too low and water levels fluctuate too

Tahle 3. Benefits 01' saltfarming in 1998 (in US$).

Tolal output 15,000 * US$37.42 =' US$561,300

Total labor costs US$269,559

Other costs Unknown*

Total max. net value of output US$291,741 (2,917 per ha)

*Not much machinery input is used in this salt farm; salt is sold in bulk, so no packaging, etc., takes place.

9

10

much this is the only place in the National Park where these birds could go to. Despite this important ecological function of the salt farm it is also argued that overextension causes an imbalance in the ecology (Rajapakse 1998).

Shell Mining

Apart from fuelwood collection, shell mining is another of the most environmentally destruc­tive activities in the study area. It extracts fossil shells from beds, which can be found just beneath" the ground surface. The shells are sifted, washed, and sold as shells or burned and sold as lime. This is a highly destructive activity because it disturbs the soil structure, de­stroys the vegetation cover, and leads to increased soil erosion (CEA 1993).

Shell mining, within the National Park and in nearby areas, is a major source of self­employment. Because of the environmental destructiveness it is prohibited by the DWLC but continues to take place. In 1998, it was estimated that there were I3 illegal shell mines inside the Park and 15 illegal mines outside the Park. There are also 12 permitted (legal) shell mines outside the park (Kularatne 1999). Usually permit holders allow others to mine the shells in their shell beds and they do not carry out any mining activity on their permit lands. They buy the shells for Rs 25 per 15 kg. Because it is possible to mine shells without a permit, people are not interested in obtaining a permit. The number of permit holders decreased from 1994 to 1997 while observations reveal that many people are still involved in this activity. As the total production of shell mining is unknown we cannot quantify the benefits derived from this ac­tivity.

Tourism

Tourism is a major income-generating activity of the Bundala National Park with only minor impacts on the economies of the nearby villages. While the activity generates a considerable amount of income for jeep drivers, guides, and guesthouses, it seems that no villagers from the vicinity receive benefits from the presence of tourists. The people involved come from villages and towns further away from the Park (CEA 1993).

The way tourism is practiced at present in the Park has a negative impact on its ecosys­tem. The main impact is on the habitat, which is being increasingly destroyed by four-wheel drive vehicles leaving the established roads in search of wildlife. This, in addition to harass­ment of animals, makes the Park less-attractive and less-habitable for wildlife (CEA 1993). Another adverse effect that tourism has had and of which villagers complain is that the ani­mals, particularly elephants, are accustomed to human presence which makes it harder for the farmers to drive them away when they damage the crops. These conf1icts result in death and destruction of both humans and elephants (Rajapakse 1998).

One of the possible impacts of drainage water inflow in the National Park could be a drop in the number of tourists visiting the area because of the changing ecosystem. So far, no clear relationship has been detected. The data in table 6 show the number of tourists visiting the area and the income derived from such visits. We have no explanation for the sudden decline of the number of tourist visits in 1996 and the increase in 1997 to the same level as 1995.

Table 4. Number of tourists and the total revenue of entrance fees for Bundala National Park.

1995 1996 1997

Number of foreign tourists 16,350 11,301 16,448

Number of local tourists 16,824 11,024 17,300

Total 33,174 22,325 33,748

Total revenue in US dollars 91,022.76 62,790.87 91,644.90

Source: Personal cOffi.ffiunication with Mr. Liyanage, DWLC

Irrigation, Drainage, and Lagoon Water Quality

Table 5 shows the average and standard deviation of major water quality parameters during the monitoring period. Additionally, heavy metal concentrations such as mercury, cadmium, and lead were tested for, but their presence was not detected. The irrigation water quality is within the acceptable limit of guideline values (table 6), except the Sodium Absorption Ratio (SAR), which is a concern with irrigation water having a given EC. This indicates the potential problem for infiltration and/or salinity and reduction of yield for sodium-sensitive crops. Ac­cording to the South African Water Quality Guidelines (Volume 8, Department of Water Affairs and Forestry 1996), the values of turbidity, phosphorus, and ammonia of the lagoon water exceed the guideline values for either aquatic ecosystems or aquaculture. Higher concentra­tions were found in most of the quality parameters of drainage and lagoon water when com­pared with the irrigation water quality parameters. Higher concentration of lagoon water is due likely to excess fertilizer from the irrigated area and livestock urine and dung from the surroundings of the lagoon.

Figure 2 shows the irrigation water issue to the right bank main canal from Lunugamwehera, and figures 3 to 9 show the trend of concentrations in some parameters in the three water bodies. During the monitoring period, the peak inflow was at the beginning of two cultivation seasons in December and May. Figure 4 shows the same EC trends of the drainage water as the lagoon water EC, indicating that the salt content of lagoon water is subject to the drainage water quality. The trends of concentration in drainage water do not clearly show a correspondence with the inflow, and only N0 shows peak concentration in

2

the months of high inflow, while the concentration of irrigation water is relatively stable. Fur­ther analysis including the loading estimate is required to clarify the relationship between the flow and water quality.

11

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. (m

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) (m

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(mg/

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(mg/

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(mg/

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(mg/

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Irri

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Lun

ugam

weh

era)

0.

32

0.16

5.

2 13

.55

7.42

0.

26

0.69

0.

01

17.5

(0.0

7)

(0.0

3)

(4.8

5)

(10.

01)

(0.6

3)

(0.4

1 )

(0.2

4)

(0.0

1)

(11.

12)

Dra

inag

e 2.

12

1.06

55

.11

40.4

2 7.

6 0.

16

1.14

0.

02

147.

83

(1.8

9)

(0.9

5)

(44.

77)

(39.

27)

(0.4

I)

(0.1

I)

(0.3

9)

(0.0

3)

(150

.63)

Lag

oon

(Em

bili

kala

) 2.

09

1.04

66

.97

57.2

5 7.

63

0.27

1.

36

0.02

91

.5

(1.8

4)

(0.9

2)

(59.

47)

(62.

50)

(0.3

7)

(0.2

5)

(0.4

9)

(0.0

5)

(46.

87)

*TD

S =

Tot

al d

isso

lved

sol

ids.

* N

TU

= N

ephe

lom

etri

c tu

rbid

ity u

nit.

** T

eU =

Tru

e co

lor

unit.

NH

3

(mg/

l)

Sus

pend

ed

solid

s

Tot

al

hard

ness

Alk

alin

ity

CI

(mg/

l)

F

(mg/

l)

Na

(mg/

l)

K

(mg/

l)

SAR

Irri

gati

on (

Lun

ugam

weh

era)

0.

08

(.06

) 15

.5

(7.6

9)

120.

33

(24.

92)

147.

67

(32.

07)

18

(7.3

4)

0.2

(0.0

6)

20.4

3 (4

.79)

3.

67

(0.5

8)

26.5

2

(5.7

7)

Dra

inag

e 0.

53

(.46

) 12

7 (9

9.23

) 54

0.5

(515

.07)

21

1.67

(6

0.59

) 44

7.83

(5

35.5

8)

0.36

(0

.10)

15

5.35

(9

7.05

) 6

(3.3

3)

110.

42

(33.

26)

Lag

oon

(Em

bili

kala

) 0.

63

(.61

) 18

3.92

(149

.12)

33

7.09

(9

6.26

)

206.

73

(30.

10)

282.

55

(147

.06)

0.

31

(0.0

5)

161.

06

(78.

56)

7.38

(4

.50)

12

5.93

(4

0.97

)

tTl

n n

n n

n n

n I:I

l I:I

l I:I

l I:I

l I:I

l<

~

~~

~~

Z

~.~

~ ~

~

~

r.

r ~

~

:>

:>

:>1

;;" ~

0

OO

::;2

:!';

!'=

!O

g

~

e;

~

a ~

er

I ~

Table 6. WHO drinking water and FAO/national irrigation water quality guidelines.

Parameter Unit WHO' FAO' South Taiwan' USA' Hun- Saudi Tuni-Africa' gary' Arabia' sia '

1996' 1985 b 1996" 1978' 1973' 1991 d No date' No date'

Aluminum AI mg/l 0.2* 5* 5 5 5 5 5

Ammonia NH 3

mg/I 1.5 *

Arsenic As Jlg/1 10 100* 100 1,000 100 200 100 100

Barium Ba mg/1 0.7 4

Benzene Jlg/1 10 2,500

Beryllium Be mg/I 0.1 * 0.1 0.5 0.1 0.1

BOD mg/1 10

Boron B rng/l 0.03 0.5-15* 0.5 0.75 0.75 0.7 0.5 3

Cadmium Cd Jlg/1 3 10* 10 10 10 20 10 10

Chloride ci- mg/I 250* 100 175 280 2,000

Chromium Cr Jlg/1 100* 100 100 100 5,000 100 100

Cobalt Co Jlg/1 50* 50 50 50 50 50 100

COD mg/I 90

Copper Cu mg/l 1* 0.2* 0.2 0.2 0.2 2 0.4 0.5

Cyanide mg/I 0.07

Electric Conductivity umho/cm 750 700

Fluoride F mg/l 1.5 1* 2 2 3

Iron Fe mg/l 0.3* 5* 5 0.1 5 5

Lead Pb mg/l 0.01 5* 0.2 0.1 5 0.1

Lithium Li mg/l 2.5* 2.5

Magnesium Mg mg/l

Manganese Mn mg/I 0.5 0.2* 0.02 2 0.2 5 0.2 0.5

Mercury (total) Hg Jlg/1 I 5 10

Molybdenum Mo Jlg/1 70 10 10 10 10 0 100

Nickel Ni mg/I 0.02 0.2* 0.2 0.5 0.2 0.02 0.2

Nitrate (NO;) mg/l 50

Nitrite (NO,') mg/l 3

Selenium Se Jlg/1 20* 20 20 20 20 50

Sodium Na mg/l 200* 70

Sulfate (SO,) mg/l 250* 200

Total Dissolved Solids g/1 1* 40

Total nitrogen N mg/1

Vanadium V mg/l 0.1 * 0.1 10 0.1 5

Zinc Zn mg/I 3* 2* 2 2 5 4 5

10,000 m3/ha/year.4 Drinking water. "lrrigarion water use = max. 'Industrial effluent used in irrigation.

"All soils. 'Sandy soils. *Recommended values.

'WHO (1993),' FAO (1992), 'Chang et al.(l996), "Department of Water Affairs and Forestry (1996).

13

-- --- -

14

Figure 2. Monthly irrigation issue to the Right Bank/rom October 1997 to September 1998.

30

25

:s c 20Q

~ E 15 ~ ~ Q 10

'<:: .s

5

0­r-, r-, r-, QJ QJ

~ ~ ~ ~'" ..: '"S '"v to '".0 ...: ...: '" u I:l c, S c'" 0 0 a'" ~ ~ <:( ...,::><: ~ ~

Figure 3. pH in the irrigation, drainage, and lagoon water.

~ QJ

~ 0, ..:<- '"

::> ::>..., ~ <:(

'"

9

5

8.5

8 /,..\ f "­

1.5 { \ I ,/ v j"

"/

~ J:: 1 ic, •6.5

6

5.5 Irrigation Drainage

r-,

..: '" u 0

r-, r-,

S'" '"v ~ to

0 I:l<: a'" ...,

QJ QJ QJ QJ QJ ~ ~ ~

.0'" '"...: ...: '" >.. '" o, '" ..: c, '" :S- ::>I:l I:l t::

<:( ::> ::> ~~ ~ ~ ..., ..., <:(

'"

Figure 4. Electrical Conductivity (EC) values in the irrigation, drainage, and lagoon water.

8

1

6

E" 5

~ 4§.

~ 3

2

0

Irrigation

.4. ~~

'\ ~__...~..-...

r-, r-, r-, QJ

..: S'" '"0

'"v '"tou 0 <: a'" ~

.,! ~ I ~ I ~ ,I Ii ; ~ Lagoon Drainage

,I \\ ~// ..

.fr \ ~ ...

! \ ,-------"'"7::1-::.-~~

--~---- -- -- -­QJ QJ QJ

~ ~ ~ ~ ~'" ...: '" ...: '"0, ..: I:l c, <­.0 S '"c ::> ::>~ <:( ::> ..., ~ ~ ~ ..., <:(

'"

Figure 5. Total Phosphorus (P04

) concentrations in the irrigation, drainage, and lagoon water.

7.6

1.4

1.2

~ 7 .g 0.8 o~

Q.. 0,6.

0,4

0.2

o

Irrigation ---

,A.

Figure 6. Potassium (K) concentrations in the irrigation, drainage, and lagoon water,

20

A.

75

•, ~ \

\

§ 70 \

"" 5

0 e-, e-,r-, 00 00

0- 0- 0- ~ 0- ~ ~ ~ ~ ~ ~ 0­0 .c x ~ 0,""u " " <::>. '" c :> :> ""c, '" ..., ..., !lJ0 ~ Q '" "'" cl:: ~ '" <l: ~'" ...,:> <l: Vl

Figure 7. Nitrate (NO) concentrations in the irrigation, drainage, and lagoon water.

3

2.5 Lagoon

2 <. ~ § 7.5 0' 2

0.5

0 Irrigation

-~~--

r-, r-, r-, 0- 0- 0- ~ ~ ~ ~ ~ ~ ~ ~ ~

0, ...: U " <::>. S c:"" 0 .c " ~'" ~ '" :> ~0 ~ Q '" .Sf " ~ '" <l: ~ ~ ~ <l: Vl

15

--

16

Figure 8. Nitrite (NO) concentrations in the irrigation. drainage. and lagoon water.

0.2

0.18

0.76 Lagoon-- Irrigation Drainage0.74

~ 0.72

"; ......\-S 0.7

1 \ O~ <: 0.08

1 \ \10.06 1,.. 0.04 1

1 /0.02 /

/

a r-,r-, 0\0\

t ,;0

0 <:

2.5

2

~ 7.5

-S :r::~

<:

0.5

a

\ \ \ \ \ \

,--~

r-, co 0\

0 c: 0\

ClJ ....,a "

co co coco co co g( co0\ 0\

-<:i ClJ ~ cj, 0\ 0\ 0\ 0\ 0\

'" 0..'" S t:: :J...., :J:J~ ~ " <>: ~ ...., <>: ~ V)

Figure 9. Ammonia (NH') concentrations in the irrigation. drainage, and lagoon water.

Lagoon

/ Irrigation JIlj, /111\ /1\,'\ I \ I \

I '11/ \

//,. ....., V / .....,'/ /' 1

:' / '/Itt- AI'"---...........-~~~~-.JIi/ ­

'---r---,~

r-, co 0\ 0\

t '"0.. o <>:

co 0\

S ~

Drainage

\. ......... ................ • '".___ --lI' ....-----­co co 0\ 0\ g( co

0\ ClJ ~ cj,t:: :J :J....,....,:J <>: ~

V)

CONCLUSIONS

Environmental services and functions of water often go unrecognized because they are not part of the primary functions of the man-made water allocation systems, like irrigation sys­tems. Moreover, environmental considerations have often been ignored in water allocation decisions, resulting in deterioration of the ecosystem.

Listing and describing all the uses and nonuses, particularly the direct uses, assist us in obtaining a better picture of what is happening in the area. Further, it reveals linkages and interactions of people and institutions in a certain ecosystem and the impacts of their activi­ties as well.

It is obvious that substantial conf1icts exist between direct uses of the resources by the local community and sustainable development of the ecosystem. The biggest conf1ict in the area (between ecosystem and livelihoods of the local people) is caused by drainage water

fr

B

01

it fo Ii-S)

p<

re to p< th FI fn

R

B<

CI

Dc

FA

In

IP

from irrigated rice fields, which enter the lagoon ecosystem. ln this context, it is important to evaluate the output of irrigated agriculture in relation to the loss of ecological value of the Bundala National Park from an economic point of view.

It is too early to conclude if the people in the area would have been better off in terms of livelihood opportunities with or without the irrigated rice cultivation. In the first instance, it provided them with a plot of land to cultivate their staple crop and a source to draw water for domestic purposes but, on the other hand, it has extremely affected the opportunities for livestock keeping and fisheries. We are however sure that it has negatively affected the eco­system in the area not only by draining freshwater into the lagoons but also by increasing population and pressure on natural resources in the area (e.g., fuelwood, pastureland).

Strict conservation of the Bundala National Park, which the DWLC is aiming for through restricting all human activities in the Park, will improve its ecological character and this is bound to increase the number of tourists visiting the area. To have a chance of success, the local people should receive more benefits from tourism than is currently the case. In other words, they s~ould also get benefits from conservation otherwise it is not a viable option for them. Further, opportunities should be created to satisfy their resource needs, for instance fuelwood, from another area or an alternative source.

REFERENCES

Bakker. M.; R. Barker; R. Meinzen-Dick: and F. Konradsen, eds. 1999. Multiple uses of water in irrigated areas. A case study from Sri Lanka. SWIM Paper 8. Colombo, Sri Lanka: International Water Manage­ment Institute.

Barbier, E. B.; M. Acreman; and D. Knowler. 1997. Economic valuation of wetlands. A guideline for policy makers and planners. Gland, Switzerland: Ramsar Convention Bureau.

Bopitiya, D.; P. N. Dayawansa; and S. W. Kotagama. 1998. The impact of domestic cattle and buffalo on the status of the Bundala National Park. In Irrigation water management and the Bundala National Park. eds. Y. Matsuno, W. van der Hoek, and M. Ranawake.

CEA (Central Env ironmental Authority). 1993. Bundala national park. Wetland site report and conserva­tion management plan. Sri Lanka: Central Environmental Authority/Euroconsult. Ministry of Environ­ment and Parliamentary Affairs.

Chang A. C; A. L. Page; T. Asano: and 1. Hespanhol. 1996. Developing human health related chemical guidelines for reclaimed wastewater irrigation. Water Science and Technology, 33(10-11):463-472.

Department of Water Affairs and Forestry. 19Y6. South African Water Quality Guidelines. Volume 8, Field guide. First Edition. Department of water affairs and forestry. Private bag X313, Pretoria, South Af­rica.

FAO. 1992. Wastewater treatment and use in agriculture. FAO irrigation and drainage paper no.47. Rome: FAO.

IIM1. 1995. Kirindi Oya Irrigation and Settlement Project. Project Impact Evaluation Study. Volume II: Annexes (final report). Colombo, Sri Lanka: International Irrigation Management Institute.

IPS (Inter Press Service). 1999. Sri Lanka: Conservation plan threatens ancient remedies. http://customnews.cnn.com!cnews/pn . . .p_sf~hcat=Sri +Lanka&p_category=Asia;

17

18

Kularatne, M. G. 1999. Fishermen without fish. The effects of productivity decline in lagoon fisheries on a fishing and farming community and its use of natural resources. A case study of Malala lagoon,

Hambantota, Sri Lanka. M.Sc. thesis. Enschede, The Netherlands: International Institute for Aerospace Survey and Earth Sciences.

Matsuno, Y.; W. van der Hoek; and M. Ranawake, eds. 1998. Irrigation water management and the Bundala National Park. Proceedings of the workshop on water quality of the Bundala lagoons. International

Water Management Institute, Colombo, Sri Lanka.

Rajapakse, C. 1998. Bundala: Social and environmental challenges. In Irrigation water management and the Bundala National Park, eds. Y. Matsuno, W. van der Hoek, and M. Ranawake. Colombo, Sri Lanka: International Water Management Institute.

Ramsar Convention Manual. 1997. A guide 10 the convention on wetlands (Ramsar, Iran 1971). 2'd edi­tion. Gland, Switzerland: Ramsar Convention Bureau.

Renault, D.; M. Hemakumara; and D. Molden. 1999. Importance of evaporative depletion by non-crop

vegetation in the irrigated areas of the humid tropics. Internal Paper. Colombo, Sri Lanka: Interna­tional Water Management Institute.

WHO. 1993. Guidelines for drinking water quality, volume I recommendation. Geneva: WHO.

IN'

Ba(

The recc acti past

cils,

wid that

ous

pro< whe

subs ing

of t wan

redi agri

hov.

tern

ogn eros chei avar

was

trial

n

1,

e

a Case Study in Mexico:

11 Urban Wastewater Reuse for Crop Production d in the I:

~Water-Short Guanajuato River Basin, Mexico [­

Report compiled hy Christopher A. Scott, 1. Antonio Zarazua, and Gilbert Levine P 1­

INTRODUCTION

Background

The need to understand water resources management with a river-basin perspective has been

recognized for many years, and attempts have been made to translate this understanding into

action. Some of these attempts have been successful, and many others failures. Within the

past few years, there has been a resurgence of interest in regional authorities and basin coun­

cils, reflecting increased recognition that it is impossible to effectively manage water resources

without considering their management in a basin context. This context explicitly acknowledges

that the productivity and equity of water use cannot be understood by considering the vari­

ous uses and users as if they were independent. There also is increasing recognition that

productivity and equity are functions of the path of use of the water from its source to a sink,

where it is no longer available for use. This sink may be the atmosphere, a saline water body­

subsurface aquifer, lake, or the ocean-that cannot be used for productive purposes (includ­

ing environmental), or a level of pollution that renders the water unusable.

Changing the path of the water through the watershed or river basin can alter the utility

of the water by shifting its use to a higher-value use, by increasing the output per unit of

water consumptively used, i.e., water that is not usefully recycled within the basin, and/or by

reducing the degradation in water quality. This last has been of significant concern to the

agricultural community for many years, particularly in relation to salinization. Tn recent years,

however, concern has broadened, both in relation to the nature of the contamination, and in

terms of the communities affected. Within the agricultural community, there is increasing rec­

ognition that agricultural activities contribute to the degradation of water quality-through

erosion and through contamination of surface waters, aquifers with residues of agricultural

chemicals, and microorganisms. There also is growing concern about the quality of water

available for irrigation as well as for domestic use in the rural areas.

This concern has grown, in significant part, as a result of the increased importance of

wastewater in the hydrology of many river basins. As urban populations grow, and as indus­

trial development expands, the volumes of wastewater produced increase at a rapid rate, and

19

I

20

their composition becomes more complex. The waste streams often include industrial wastes, such as heavy metals, acids, and derivatives of plastics, in addition to the organic compo­nents characteristic of human wastes.

The importance of safe discharge of wastes to the environment is widely recognized, both in terms of implications for public health, and for the environment more generally. Waste­water contains the full spectrum of enteric pathogens endemic within a community. Many of these can survive for weeks when discharged on the land. Of particular concern, from a public health perspective, are the helminths (ascaris and trichuris), which have relatively long persis­tence and have a small infective dose. Notwithstanding the presence of infective organisms, however, epidemiological studies have shown that the mere presence of pathogens does not necessarily increase human diseases. As a result of these studies, the guidelines for the safe use of wastewater have been revised and are less stringent than originally proposed.

From an environmental perspective, the use of wastewater for agricultural production has benefits, as well as potential problems. The latter-potential contamination of groundwa­ter with nitrates, heavy metal accumulation in the soil, development of habitats for disease vectors, such as mosquitoes and snails-are widely recognized (though not well-defined in most situations). The former, however, are not as widely acknowledged. In addition to a major benefit for the environment-reduction in pollution of surface waters-there are significant economic benefits. Nutrient-rich water is made available for irrigation, resulting in higher yields with fewer purchased inputs. And, land application of wastewater is a low-cost method for sanitary disposal.

The need for low-cost sanitary disposal of wastewater has resulted in widespread use of wastewater for agricultural and aquacultural purposes. While reuse occurs widely, and guidelines for that use are available, these generally identify the water treatment required for different uses. In the case ofland application of wastewater, there is little specific reference to the composition of the wastewater as it is used at the field. In part, this is because composi­tion is not often measured, even at the source. Even in those situations where the composi­tion is determined at the source, i.e., the sewer outfall, use frequently takes place at a substan­tial distance. In these cases, the composition of the wastewater can change significantly, es­pecially if transport is through a natural channel subject to aeration and/or sediment deposi­tion. To evaluate the appropriateness of use of wastewater for irrigation in individual situa­tions, information about the composition at the field level is necessary. Given the cost of sample collection and analysis, there is a major need for a procedure that would predict, with appro­priate precision, the pollutant composition of the waste stream as it moves downstream to points of use. The study reported here evaluates the utility of the Interactive River Aquifer System (IRAS) model for this purpose, and illustrates its application in a water-short area in Mexico where urban wastewater is being used for irrigation.

Mexico

Mexico is committed to increasing the effectiveness with which its limited water resources are used. As a base for this effort, it has adopted the principle of river-basin planning and man­agement. To implement this principle, the country has been divided into thirteen Regional Water Authorities, under the Comision Nacional de Agua (CNA). Within three of these regions, River Basin Councils (Consejos de Cuencas) have been created to ensure user participation in the

critical establis ensure 1

with du In

has este

mandan

well as taminar

WAS1

Mexico i.e., wit

o creased Lake, a of flooc torical :

These c TI

implem ment ar ondary used in fromM lagoon, ter qual erated i

Table 1

Source/F

Wastewa

Primary

green.

Primary

Texcoco

Tertiary

groundw

Untreate

critical decision making associated with river-basin management. Additional councils are to be istes, established in the remaining areas. Fundamentally, the councils will have the responsibility to rnpo­ensure that the scarce water resources will be used productively, efficiently, with equity, and with due consideration of the impacts on the natural environment. iized,

In recognition ofthe increasing importance of wastewater in river basin hydrology, Mexico Taste­has established water quality norms for the different types of water uses. In addition, it has nyof mandated different levels of wastewater treatment for significant waste streams, industrial as ublic well as municipal, many of which are untreated, i.e., there is no process for reducing the con­ersis­taminant load before discharge to the environment. isms,

s not : safe

WASTEWATER IRRIGATION IN MEXICO ction dwa-

Mexico City is the largest urban population in the world that lives in a closed hydrologic basin, sease

i.e., with no natural outflow to the sea. It is also the largest user of wastewater.ed in

Over the years, attempts to control flooding, changes in watershed land uses, and in­najor

creased water use have resulted in drastic changes in the hydrology of the basin. Texcoco icant

Lake, a shallow freshwater lake located in the outskirts of Mexico City disappeared as a result ields

of flood control, and over-pumping of the underlying aquifer. In addition, tunnels-both his­j for

torical and modern-are used to reduce flood risks and to carry wastewater out of the basin. These changes have now caused increased concern for the general ecology in the area.

I use To reduce the problems now evident in the basin, a lake reclamation project is being

and implemented that makes use of the wastewater from Mexico City. Three types of water treat­

Hor ment are being evaluated: primary treatment, using a 6S hectare (ha) lagoon, primary and sec­

ce to ondary treatment, and tertiary treatment resulting in drinking water quality. The wastewater

oosi­used in this demonstration/research project is approximately 3 percent of the total effluent

oosi­from Mexico City that uses three different kinds of treatment: primary treatment by the 6S-ha

stan­lagoon, primary and secondary treatment, and complete treatment for producing drinking wa­

', es­ter quality. Table I lists the breakdown of the approximately 4S m3/s of wastewater flow gen­

iosi­erated in Mexico City.

itua­nple pro­n to

Table 1. Mexico City wastewater flows and their uses.lifer

-a in Source/Fate Flow (rn 'Is) Comments

, Wastewater generated in Mexico City 45

Primary treatment for irrigating parks/ Could irrigate upto 10,000 ha of land, but may be

green areas within Mexico City 10 used to maintain wetlands and "floating gardens."

Primary and secondary treatment for Reclamation of sodic soils, reforestation. and

; are Texcoco Lake Reclamation 1.0-1.5 Nabor Carillo Lake.

1an­ Tertiary treatment for animals and/or Sedimentation, flocculation, filtration (sand,

groundwater injection, Texcoco Lake 0.05 activated carbon), chlorination.Tater Untreated wastewater 34 Discharged to Tula Irrigation District (Hidalgorver

State) through a network of tunnels. one> 60km.the

21

I

22

Of particular interest to the project reported herein is the experience with wastewater

irrigation in the Tula and Alfajayucan irrigation districts. Tula (approximately 100,000 ha of

official and unofficial command area, and growing) is considered the largest contiguous area

of wastewater irrigation in the world. Historical records indicate that by the late nineteenth

century, Mexico City wastewater was already being used for irrigation in this area. As the city

grew, so did its waste volumes, and by extension, the area irrigated in Tula. The characteris­

tics of the districts are illustrated in table 2.

Tahle 2. Characteristics of Tufa (No. (03) and Alfajayucan (No. 100) irrigation districts.

Tula Alfajayucan

Total command area (ha) 45,125 33.051

Number of water users 31,316 19,540

Water source Mexico City wastewater, plus Mexico City wastewater, plus

reservoirs with combined reservoirs with combined

capacity of 278,119,000 m' capacity of 254,700,000 m'

Area irrigated with drainage return tlows (ha) 10,000 Unknown

The majority of the wastewater enters a reservoir before being distributed to the irriga­

tion districts. The detention time in the reservoir is sufficient for some natural remediation.

However, to avoid potential health problems, farmers are constrained by regulation in their

cropping options; no vegetables or fruit can be irrigated with wastewater, leaving maize and

alfalfa as the major crops.

The area experiences some problems identified explici.ly with the use of wastewater. The

reservoir has no surviving fish, and the potential growth of aquatic weeds is such that a major

program of control is necessary to maintain the use of the outlet structures. A relatively small

area, approximately 500 hectares, is affected by waterlogging and salinity. Information on health

problems experienced by the water users is not readily available, though informal discussions

with users did not reveal major concerns.

On the positive side, the wastewater provides an abundant source of irrigation water,

though this is reducing as Mexico City uses more of the water internally. Figure 3 shows the

irrigation depths used in the area; these are substantially higher than irrigation in other dis­

tricts. The wastewater provides plant nutrients not present in non-sewage water, and the farmers

use little, if any purchased fertilizer. A number of studies have been carried out in the district,

including water quality. It is clear from our study result that nutrients and biochemical oxygen

demand (BOD) are retained in the soil, while salinity gets worse from head to tail. Another

recent study showed that EC of wastewater is around 1.6 mS/m, pH is lower than 7.5, and e­coli ranged from 10) to 101

) per 100m!.

Water Quality Trends in the Tula Irrigation District

As indicated previously, Mexican legal norms specify the standards for use of wastewater in

irrigation, and these limit the use of untreated wastewater to basic grains (maize, sorghum,

wastewater

0,000 ha of

iguous area

: nineteenth

.As the city

characteris­

1 districts, , I

ater. plus ned

100 m'

I the irriga­

:mediation.

on in their

maize and

:water. The

iat a major

vely small

1 on health

iscussions

ion water,

shows the

other dis­

lC farmers

re district. taloxygen

. Another t

.5, and e-

and wheat) and fodder (alfalfa). While some clandestine irrigation of higher-value crops un­

doubtedly takes place, the crop restrictions clearly limit the agricultural profitability. As a re­

sult, though this may not be the only reason, the Tula and Alfajayucan irrigation districts are

among the few in Mexico that have not accepted responsibility for operation and maintenance

under the government program of transfer of responsibilities to the users.

FIELD RESEARCH PROGRAM

The City of Guanajuato has water management interests that span the watershed. Its basic

water supply includes both surface water, impounded in two principal reservoirs located in

the upper part of the watershed, and groundwater pumped from one main aqui fer in the cen­

tral part of the watershed. It releases wastewater to the downstream part of the watershed,

ultimately reaching La Purisima reservoir, which serves as the water source for part of Irriga­

tion District 0 II.

Since the cost of groundwater is approximately six times that of the gravity surface water,

the city has a strong interest in maintaining the water producing characteristics of the water­

shed, as well as in the potential for use of the wastewater to reduce demands on the city water

supply.

Similarly, the current users of the wastewater have interests in the future disposition of

wastewater. These users are small-scale irrigators, organized in unidades,' whose water sources

include the wastewater, flows from natural rainfall, and groundwater. The wastewater repre­

sents a significant part of their water supply, especially during the dry season.

This combination of circumstances raises a number of questions specific to the loca­

tion. The Guanajuato City water authority (SIMAPAG) has special concern for the following:

1. What level of treatment would be necessary to increase the use of wastewater

internal to the city?

2. What monetary value would this treated water have?

3. What are the legal implications of reducing the outflows to the downstream irriga­

tors?

In addition to these specific questions, however. the situation in Guanajuato provides

an opportunity to address some generic questions of broader applicability:

1. Land application of wastewater through irrigation serves as a waste treatment

process, with benefits and problems for the irrigators. What is an appropriate basis

for charging or compensating the wastewater users?

2. Irrigators using untreated wastewater discharged into natural streams, over time

in many situations, acquire a de facto right to the water. How should de facto water

rights be addressed when water treatment reduces wastewater outflows?

ewater in

sorghum, lUnidades are organizations of irrigators that are user-managed, often with some governmental oversight.

23

24

3. Wastewater application to the land uses the land as the sink for nondegradable

contaminants, e.g., heavy metals. How should this environmental externality be

valued?

The research reported here addresses the foregoing, in the context of the specific situ­

ation in the Guanajuato basin.

METHODS AND MATERIALS

Field Data Collection

To identify the major hydrologic features of the river between the city and the Purisima reser­

voir, IWMI staff accompanied by the SIMAPAG Operations Engineer walked the l2-km reach

prior to developing field data collection plans. This reconnaissance served to locate the prin­

cipal wastewater, natural stream discharges into the river, and irrigation diversions. Subse­

quent fieldwork allowed us to pinpoint flow gauging and water quality sampling points on

I :50,000 topographic maps and a digitized air photo. Contact was also made with farmers who

irrigate with the wastewater, to understand the rules governing water allocation and sharing

both among and within the peri-urban communities of San Jose de Cervera and Santa Catarina.

These were selected because they utilize raw wastewater not subject to water quality changes

based on return flow, and because they have the largest areas irrigated with wastewater.

Field research activities were designed to address three objectives as indicated in table

3. The data collection strategy adopted in each case, with the date of fieldwork and numbers

of samples collected are also presented.

In all cases, water samples were collected in triplicate (every 10 minutes over a 20-minute

time span) to characterize the natural variability that occurs under environmental conditions.

Temperature, pH, and conductivity measurements were made in the field, and the samples were

put on ice for subsequent transport to the laboratory where they were refrigerated until analysis.

Tahle 3 Field research design.

Objective Strategy Sampling Total no.

dates samples

I. How are the major water Sample single slugs of wastewater as 16-N ov-98 87 water

quality constituents trans- they flow down the reaches (main river 4-Dec-98 samples

formed during in-stream channel and one irrigation canal).

transport?

2. What temporal variations Sample multiple slugs distributed 19-Feb-99 48 water

exist for the constituents throughout the day (one irrigation samples

in the source wastewater') canal from the river diversion to

the irrigated field).

3. What residual cont am i- Compare soil and water quality for 15-May-99 36 water

nation is present for wastewater-irrigated plots V.I. fresh samples wastewater-irrigated soils (groundwater)-irrigated plots. 12 soil and shallow groundwater? samples

Biochel1

The sam

oxygen (

determin

Total PI

Colorime using an

All calib

Total N

TN was

poundsl

catalyst. in the ac

The dig.

boric ac

Total C

TC was

dishes" measuri

Solids

Total Sl

from a

(TSS) \

dissolv

egradable

rnality be

cific situ­

ima reser­

-km reach

: the prin­

rs, Subse­

points on

mers who

d sharing

Catarina.

I changes

vater.

d in table

numbers

~O-minute

mditions.

pIes were

analysis.

"oral no.

samples

n water samples

·8 water samples

6 water .amples

12 soil

,amples

Biochemical Oxygen Demand (BOD)

The samples were diluted in autoclaved vials and incubated at 20°C for 5 days. Dissolved

oxygen (DO) was measured using the Winckler method, before and after incubation. BOD was

determined as the difference between the initial and final measurements of DO.

Total Phosphorus (TP)

Colorimetry was used to determine TP (converted to orthophosphates Hl0 ' , HP0 2. , and PO/")

4 4

using ammonium molybdate under acidic conditions to form ammonium phosphomolybdate.

All calibration curves had correlation coefficients of 0.95 or higher.

Total Nitrogen (TN)

TN was determined using the Kjelhdal method, in which nitrogen-containing organic com­

pounds are digested in sulfuric acid in the presence of potassium sulfate and a copper sulfate

catalyst. Organic matter is digested to form CO and H thereby releasing ammonium, which 2 20,

in the acidic digestion medium, is immobilized as a nonvolatile salt such as ammonium sulfate.

The digested solution is alkalinized and ammonium nitrogen in the distillate is absorbed in

boric acid, which is finally measured by titration.

Total Coliforms (TC)

TC was determined using the viable count method. I mL dilutions were inoculated in Petri

dishes with agar at 45-48 °C and subsequently incubated for 24-48 hours. Dark red colonies

measuring 0.5 mm or greater with a precipitation halo were counted and reported as cfu/mL.

Studies of coliforms ill tropical climates found that E. coli comprised,

on average, 14.5 percent of the total coliforms isolated... [Ilt would

appear there is no benefit in using faecal coliforms as opposed to

total coliforms as both groups give equally inaccurate results ...

[T]here are considerable douhts about the validity of using coliforms as indicator organisms in tropical countries. (pp. 56-57, Gleeson, Cara

and Nick Gray. 1997. The Coliform Index and Waterborne Disease E &

FN Spon. London)

Solids

Total solids (TS) were determined by weighing the residual material after evaporating water

from a completely mixed sample in a porcelain crucible at 100-105 "C. Total suspended solids

(TSS) were determined by weighing the residual on a micropore filter, dried at 100-105 "C. Total

dissolved solids (TDS) were determined as the difference TS- TSS.

25

26

RESULTS Simulat

two COl

Total nitrogen with distance down the main river channel (the horizontal line shows Mexican

norms for maximum permissible limit). 140

720

100 c OJ C» 80g'c:

60E t2

40

20 L0 0 1,500 3,000 4,500 6,000 7,500 9,000 10,500 72,000

Meters

Total phosphorus with distance down the main river channel (Mexican norm for maximum

permissible limit = 30 mgIL). 12

71

10

'" 2 9 c ..c:: 5;- 8 o .c Q 7

E 6t2 s 4

3 I­

2.

7.

7.

-J 7. ~ <::>

:§ 8.

~ 6.

4,

2,

O.

0 1,500 3,000 4,500 6,000 7,500 9,000 10,500 12,000

Meters

Conductivity (shows concentration of salts in irrigation return flows to the river).

7,500 3,000 4,500 6,000 7,500 9,000 10,500 72,0000

Meters

c­ 7,150'S: 'i:: v 7,700~

'" c 1,050o

\..J

7,000

950

900

7,300

7,250

7,200

'Ie shows Mexican

12,000

rm for maximum

=--J0 12,000

river).

iJr12,000

Simulation modeling (compare IRAS simulated parameter behavior with observed values at two control points C5 and C9 down the main river channel).

120 BODS

100

80

~ 01 60E

Simulated

20

0

40

C5 C9

2.£+07 Total cotiiorms

1.£+07

1.£+07

--J 1.£+07E c

§c 8.£+06

::J 6.£+06 ­

4.£+06

Simulated Simulated2.£+06

0.£+00 C5 C9

10 -,---------------------------------; Total phosphorus

9

8

7

6 ~ 01 5 E

4 Simulated 3

2

1

o +---"----­C5

,------,

Simulated

C9

27

I

--

28

100 -,----------------------------~

Total nitrogen90

80

70

60

50

40 Simulated30

20

10

o -+-----'------­

CS

Simulated

C9

120 -,-------------------------------, Total dissolved solids

100

80

60

40 Simulated Simulated

20

0+-----'------­CS C9

2500,--------------------------------, Total suspendedsolids

2000

1500

1000

500

Simulated

0+------'------­CS

r----,

Simulated

C9

Observations 011 Model Simulations

The model simulated the behavior of BOD and total phosphorus with a high de­gree of correlation with observed values.

The model simulated total nitrogen, and total dissolved solids with an acceptable degree of correlation with observed values.

The model did not simulate pH, conductivity, total coli forms, or total suspended solids with appreciable correlation with observed values.

CONCLUSIONS

There is evidence that even within relatively short distances there are significant return flows to the river. This is corroborated by the conductivity data.

Tradeoffs in the use of wastewater:

a. Nutrient deliveries to the irrigated fields are a function of the amount of water used, and the concentrations of the various nutrients. Both of these variables change with the seasons, with higher use and higher concentrations occurring during the dry season.

b. As indicated earlier, the nutrient whose concentrations are in excess of the stan­dards is nitrogen. While from a public-health standpoint this excess has signifi­cant implications, particularly in terms of potential contamination of the ground­water, nitrogen is an important agricultural nutrient.

c. There are two potentially negative aspects in the trade-off evaluation-adverse health and environmental impacts. These were not addressed systematically in this study. The potential adverse health impacts of irrigation with wastewater have been reported in a number of articles. The successive reuse of the wastewater in this particular basin suggests that these adverse effects may be smaller than in situa­tions without reuse. The passage through field vegetation and/or the filtration that accompanies irrigation and subsequent runoff and drainage would be expected to reduce the parasite and other microorganism level, in addition to the observed changes in chemical concentrations.

d. The major environmental impact that could be anticipated is increased eutrophica­tion in La Purisima reservoir, due to the phosphorous inputs from the wastewater. While the concentration of phosphorous in the water is relatively high, the flow from the wastewater path represents a small percentage of the total annual flow into the reservoir. Thus, the loading level is relatively low. Similarly, the salinity contribution from this source, while at a higher level due to the reuse upstream, is not likely to represent a significant problem.

29

30

e. The extended use of wastewater for irrigation carries with it the potential for accu­mulation of heavy metals. The available information did not permit the determina­tion of rates of accumulation because of potentially large changes in wastewater composition resulting from historic changes in mining in the region, as well as changes in the urban population. Notwithstanding this, the levels found in our limited field study suggest that heavy metals do not represent a significant prob­lem.

potential for accu­rmit the deterrnina­iges in wastewater region, as well as evels found in our a significant prob-

Limitations of Irrigation Water Quality Guidelines

from a

Multiple Use Perspective

Report compiled by P.K. Jensen, Y. Matsuno, and W. van der Hoek

INTRODUCTION

Agriculture consumes between 70-90 percent of available freshwater in developing countries. With the present population growth, more food will have to be produced. At the same time, the requirements for water of urban areas, industries, and the environment are increasing rap­idly. There is therefore an increasing pressure on the irrigation sector to produce more food with less water by making irrigation more efficient and by using recycled water of lower qual­ity. As a tool to assess the adequacy of water quality for irrigation use, guidelines have been developed by irrigation and water resources authorities in a number of countries and by inter­national organizations such as the Food and Agricultural Organization. These guidelines nor­mally contain threshold values based on certain criteria such as optimum crop yield, crop quality, soil suitability, and maintenance of irrigation equipment (DWAF 1996). Different sets of guide­lines are available for other sectors, especially the drinking water sector (WHO 1993) and the environmental sector (US-EPA 1990). In the following, we argue that with the increasing scar­city of water and the changing vision on freshwater resources in the context of integrated water resources management, there is a need to review the different sectoral water quality guidelines.

In the first place, apart from irrigating crops, irrigation water is used for many other purposes. These nonagricultural or "multiple" uses were first described in a series of reports commissioned by the Agricultural Development Council and the U.S. Agency for International Development in the early eighties. Recently, the International Water Management Institute took up the task of systematically describing the multiple uses and users of water to ensure that water resources policy take all these uses and users into account. Case studies were com­pleted in Sri Lanka and Pakistan (Bakker et al. 1999; van der Hoek, Konradsen, and Jehangir 1999) and these showed that irrigation water was crucial for domestic uses, small-scale indus­tries, livestock, inland fisheries, and to sustain the local environment and biodiversity, espe­cially in wetlands. The nonagricultural uses of irrigation water are site-specific and depend on geological, socioeconomic, and cultural settings. They have been unrecognized or even ig­nored by policy makers and project planners. This was partly due to the research community's sectoral approach to water. None of the currently available guidelines or investigations con­siders the intensive multiple use of irrigation water in developing countries. It is assumed that the water is used strictly for agricultural purposes and that alternative sources of water are available for other uses, including domestic use.

32

Second, even if water is applied to fields for irrigation of crops, a considerable part will

not be used for crop evapotranspiration. In older terminology these were considered "losses" but the reality is that this water is often reused further downstream for agricultural or nonag­

ricultural purposes.

Third, when water becomes scarce in river basins there is increasing competition for

water between different uses and the same source of water could be used for different pur­

poses at different times.

Last, wastewater from cities and industries is increasingly used for irrigation. Special

guidelinesare available for irrigation with polluted water, such as urban wastewater, and these incorporate human health issues (WHO 1989), but again the guidelines are developed for one

particular use and do not take other possible uses into account.

The aim of this paper is to discuss the adequacy of prevailing irrigation water quality

guidelines for the protection of multiple users of irrigation water in an environment of increas­

ing scarcity and competition. Special emphasis is given to the drinking water requirements of people in the irrigation schemes of the developing world. The paper will not go into details

regarding all the specific parameters of the current guidelines but use the example of cadmium

(Cd), a pollutant with known adverse effects on crop yields and human health.

PRINCIPLES FOR IMPROVED GUIDELINES

Cadmium enters the environment mainly from anthropogenic activities. It accumulates in aquatic

and terrestrial flora and fauna and its serious effects on human health have been described in

detail (Irwin et al. 1997). There are two important principles for water quality guidelines. First,

even if Cd levels remain below accepted irrigation water quality standards, it accumulates in the soil of irrigated fields if output of Cd is below input. Second, too high concentrations of

Cd in water and soil have adverse impacts on crop growth and pose an immediate hazard to

aquatic and terrestrial flora and fauna and human health. We refer to these two principles as

the sustainability principle and the hazard principle.

SUSTAINABILITY PRINCIPLE

The sustainability principle entails that irrigation water should not contribute to a net accu­

mulation of substances that are alien and hazardous to the agricultural soil, the surrounding

natural environment, crops, animals, and human beings. In other words, the import of such

substances via irrigation water in a certain period of time should be equal to or less than the amount that is exported from the irrigated system. The accumulation of cadmium mass

(Maccumulatio) in irrigated land can be expressed as:

n

Maccumulation = L u. (1) 1=1

mos sub:

avo

redi

yiel

fool

COUI

met that

Thu

acct

met fow

ing

(Ch

seer tion

inle

coru

At 1 plar

cro!

soil

envi

witl line:

(EU org~

198~

be c

siderable part will

msidered "losses"

cultural or nonag­

g competition for

for different pur­

rrigation. Special

tewater, and these

Ieveloped for one

.ion water quality

rirnent of increas­

r requirements of

ot go into details

nple of cadmium

Ith.

ulates in aquatic

en described in

uidelines. First,

accumulates in

ncentrations of

Iiate hazard to

D principles as

o a net accu­

surrounding

iport of such

less than the

lmium mass

Where D~ is the change in Cd mass of the soil in a specific time interval (i), which can

be explained by the simplified mass-balance equation:

11M; ~ Min - Maut - Muptake (2)

Where ~n is the mass of Cd imported to the field through irrigation water, fertilizer, at­

mosphere, and the other sources, M is the mass exported from the field through surface and o ur

subsurface drainage, and M • is the mass taken up by crops. uptace

It is obvious from the above equation that /).~ must be equal to or less than zero to

avoid Cd accumulation in the soil. The equation also indicates that to lower tlM" either a

reduction in M or an increase in M or M • has to be achieved. In out uptatce

However, M • should be low to avoid human exposure of Cd and reduction of cropupcace

yield. It is estimated that in Denmark over 80 percent of the human Cd exposure is through

food which originated from cultivated land. This is more or less the same in all industrialized

countries. Concurrently, Cd affects to the yield because it readily interferes with some plant

metabolic processes and is therefore toxic to many plants (DWAF 1996). Several studies found

that the Cd concentration of crops is positively correlated with the content of Cd in field soils.

Thus Min needs to be minimized to keep soil Cd low and should be lower than M,mt to prevent

accumulation in the soil.

Applying irrigation water to virgin land would inevitably create an accumulation ofheavy

metals due to sorption on the soil layer. In the case of Cd, nearly all of the applied ions are

found in the topsoil due to the strong sorption. However, it has been observed that after fill­

ing of the available attachment sites, the soil particles gradually decrease the sorption rate

(Christensen 1989a). Simultaneously an increase in the drainage water concentration will be

seen until equilibrium is reached where the inlet concentration equals the outlet concentra­

tion. In an arid climate, the drainage water concentration (in the equilibrium) would exceed the

inlet concentration due to evaporation of the inlet water. The evaporation will also allow the

concentration of salts to increase, which would reduce the adsorption rate of Cd to the soil.

At the equilibrium the soil water concentration would be high and metals are available for

plant uptake. In this situation even toxic problems regarding the heavy metal concentration in

crops could occur.

Combining the sustainability principle with actual soil concentration values for different

soil types and for different climates would lead to an adoption of the guidelines in a variety of

environments. The maximum limitations have been used in the EU for a number of years, mostly

with regard to application of sewage sludge to the agricultural soil. According to EU guide­

lines a maximum of 0.15 kg of cadmium per hectare per year can be added to agricultural land

(EU 1986). These guidelines however do not take into consideration the soil type and the

organic contents factor on which the cadmium sorption depends (Lee et al. 1998; Christensen

1989b).

Since there is a possibility of very high single loads the sustainability principle has to

be combined with the hazard principle already known from today's guidelines.

33

34

HAZARD PRINCIPLE

The hazard principle considers concentrations in the irrigation water while the sustainability principle looks at the mass per hectare. The hazard principle is more an irrigation system / watershed parameter while the sustainability principle could, in theory, be applied to the indi­vidual field level. While the hazard principle is concerned with both acute and long-term ef­fects, the sustainability principle is only concerned with the long-term effects. The hazard principle will need to be adapted to the maximum tolerance levels for the local uses of the water, but wil1 depend as much as the sustainability principle on local geographical/climatic conditions. The hazard principle has to consider the crops' tolerance levels and the multiple users' requirements, but with a special emphasis on the latter since these are often direct and most vulnerable users. This is especially the case when drinking water is taken without treat­ment from irrigation canals or shallow groundwater for use of the population living in the ir­rigated area.

Ideally, when evaluating the guidelines for an area, all demands for water quality should be met. In an area where drinking water is drawn directly from the canals, the irrigation water should ideal1y live up to the guidelines set out by WHO. However, simply adopting the most stringent guidelines, i.e., those for drinking water is obviously not a realistic solution. Instead, first priority must be to find a drinking water supply that can meet the minimum demands from WHO. This is often done by supplying shallow seepage water wells which are low cost and if maintained properly a much better alternative from a water quality point of view than the canal water. Utilizing seepage water is a practice used in many irrigation schemes all over the developing world.

For example, in Pakistan large populations in irrigation schemes can be totally depen­dent on irrigation water for all their water needs because of very low rainfall and brackish groundwater conditions (Jensen et al. 1998). Drinking water is drawn directly from the canals or indirectly from wells located close to the canals or fields to utilize the seepage water.

IRRIGATION AND DOMESTIC WATER SUPPLY

Is it possible with the existing guidelines to ensure an acceptable quality of drinking water supply in an irrigated area? Lee et al. (1998) have studied the Cd leaching from four different soil types in Taiwan in relation to possible groundwater pollution. Their aim was to relate a specific soil concentration of Cd to the Cd concentration of a water sample after being leached through the soil sample and thereby to estimate possible groundwater concentrations of Cd in an aquifer underlying a topsoil with a known Cd concentration. The experiments were car­ried out under different pH values and with soil types varying from sand to loam. The experi­ments were conducted as batch experiments but it has been shown that there is a good cor­relation between batch experiments and column flow experiments, e.g., seminatural conditions (Lee et al. 1998). The study by Lee et al. (1998) produced a Soil Metal Criteria (SMC) which state the maximum allowable soil metal concentration when the soil water concentration (C

w)

does not exceed the drinking water guidelines:

-------------------------

----

iile the sustainability

n irrigation system I e applied to the indi­

ite and long-term ef­

effects. The hazard

the local uses of the

teographical/cl imatic

rels and the multiple

~ are often direct and

~ taken without treat­

\tion living in the ir­

water quality should

lthe irrigation water

\y adopting the most

ric solution. Instead,

Imum demands from

ph are low cost and

Int of view than the

\chemes all over the

r be totally depen­

Infall and brackish

't!y from the canals

eepage water.

lof drinking water

rom four different

im was to relate a

~er being leached

pentrations of Cd

riments were car­

loam. The experi­

Ire is a good cor­

latural conditions

ria (SMC) which

mcentration (C ) w

L_

35

SMC = (Drinking Water Standard) x ( Kd+ _ Pc f-)) (Lee et al. 1998) (3) l d, l-p

and

CKd= - (Lee et al. 1998)(4)Cw

where, Kd

is the distribution coefficient, C, is metal concentration in soil (mg!g), C" is

metal concentration in water (mg/l), d is density of soil particle (g/ml), p is the porosity of soil,s

and f is the degree of water saturation in soil.

K values vary greatly depending on the soil properties, e.g., pH, texture, organic matterd

contents, etc. According to Christensen (1989a), K will double approximately for each 0.5 pH d

unit increase Of 2 percent increase (weight basis) in organic matter content.

The C\\ represents the pore water concentration, which is initially (at the moment of

application) equivalent to the irrigation water concentration. However, according to Christensen

(1984), 95 percent of the sorption will happen in the first 10 minutes of contact and total equi­

librium reached after I hour. Therefore, in the following, the pore water will be taken as equiva­

lent to the drainage water concentration.

Table I sets out the five soils and their properties used in the Lee et al. study. Further­

more, SMC values are calculated with the background of WHO standard whereas Lee et. al

(1998) did the calculations with Taiwan standards.

Table 1. Fire different Taiwan soil properties and their SMC values at different pH (adopted

from Lee et al. 1998).

Soil type Clay Soil Org. EC Soil SMC* SMC* SMC* SMC*

and location pH matter at al at atK"

------------ ----------~~~-~-~-~~~-~~y~ (/c; In lJt meq! l(kg mg Cd! mg Cd! mg Cd! mg Cd!

CaCI, 100g kf! kg kg kg

Wan-Ii loam 11.5 6.51 3.8 1.0 1595 O.\2 0.51 I. I I 4.80

Kuei-jen loam 9.0 6.38 0.9 8.1 303 0.06 0.12 0.36 0.9

Hu-Tou-pi sandy loam 10.0 3.96 0.8 8.1 22 0.06 0.21 0.60 006

Niu-choiu-pu sandy loam 12.0 4.81 0.3 85 24 0.03 0.09 0.21 0.06

Hu-san farm sand 6.5 6.89 1.\ 7.3 462 0.09 0.2\ 0.66 1.38

*Drinking water standard set to 3 mg/l (WHO standard for drinking water).

To see the practical implications of the guidelines, we considered a water user under the

following circumstance as an example: A typical multiple user, who is drawing all hislher drink­

ing water from a shallow well receiving the seepage water from an irrigated field, with the

seepage water drawn beneath the ground level. In this case, the SMC value would be the

highest permissible concentration of the soil at which the seepage/drainage water is the WHO

guideline value. Figure 1 shows the estimation of changes in numbers of years that the Cd

concentration of seepage water reaches the WHO limit with different SMC values and irriga­

tion applications.

36

Figure J. Difference in numbers of years that take Cd concentration of seepage water to reach the WHO guideline values (3mg/l) in different SMC values and irrigation depths.

3,500 1.8

>::­

'" <lJ

3,000 , , ; 1.6

1.4 ~ E .§.

-£ ~ " <::: .2 0

~

2,500

2,000

1,500

1,000

500

0 , , , ,

SMC

I

I

I ,, , , ,

I

I

I

Irrigation depth

1.2 0\ ~ ~ ~

0.8 ~ u ~ 0.6 V)

0.4

0.2

0 0 20 40 60 80 100 120 140

Years to reach the WHO limit

Assumptions on the estimation were: 1) the limit of drinking water quality is 3 mg/I, given

as the WHO guideline value, 2) Cd concentration of irrigation water is 10 mg/I, 3) 80 percent

of applied Cd is sorbed to the soil particles (Lee et al. 1998),4) No Cd in the soil prior to the

irrigation, 5) the bulk density of soil is 1.6 g/ml, 6) 3,000 mm /year of irrigation water is applied

for the estimation of years in different SMC values (This is assumed in a tropical monsoonal

climate with a double cropping rice cultivation), and 7) SMC is set to 0.9 mg/kg for the estima­

tion of years in different irrigation depths.

This example shows significant variations in the numbers ofyears in different SMC values.

In the range of SMC presented in table 1, the difference is more than 100 years. It also shows

a variation by irrigation depths, indicating difference of shallow groundwater quality in differ­

ent climate and cropping patterns since the required irrigation depth depends on the evapo­

transpiration. These results imply that the criteria of water quality are subject to local condi­

tions such as soil, climate, and land use patterns.

DISCUSSION

Two main conclusions can be drawn from the calculated example: First, it is necessary to take

account of nonagricultural uses of irrigation water in irrigation water quality guidelines. Sec­

ond, there is a strong need to incorporate both a sustainability and a maximum concentration

principle in future guidelines.

Even within a relatively small country like Taiwan, there are big differences in the ability

of soils to accumulate heavy metals as demonstrated in the above example. If one national

guideline based on the hazard principle were to be implemented, it would have to be based on

the soil with the lowest potential and therefore create extremely strict guidelines for the entire

country. The example also shows that the traditional way of classifying soils for guideline use

is not strict enough when dealing with a heavy metal like cadmium. As seen in table I, there

are big differences in the SMC ofthe soil within the same soil classification. Therefore, factors

such;

lines

ral gi:

place

ating

ing is

prove

future

mente

indust

for cc

REF

Bakke:

are

me

Christl anc

Christl ete

Christl Pol

Depart

gui

Depart

urn

bag

Europt

din

FAO.

Irwin,

nat

ute

Jensen Pul

not

Lee, S grc

US-EI EP

van de

or

er to rs.

tiven 'cent i the ilied onal ima­

ues. ows 'fer­IpO­ndi­

ake ec­IOn

lity Ilal on Ire tse

~re

Irs

such as the soil's Kd value will have to be taken into consideration when establishing guide­lines for sensitive areas where intensive multiple use is taking place.

The future guidelines should be based on a multiple use evaluation including the natu­ral given factors of soil, climate cropping pattern, etc., and this evaluation will have to take place every time the mentioned factors change. It may be argued that this procedure of evalu­ating different environments and their capability of handling different external pollution load­ing is a cost- and time-consuming process but, on the other hand, if done properly it would prove to be of great benefit to the individual country, protecting the environment, present and future generations, and agricultural production. Guidelines of this kind should be ideally imple­mented in such; way that land currently set aside for irrigation with inferior wastewater for industrial cash crop production (cotton, etc.) could be converted to a low-risk field suitable for consumer crops in the future.

REFERENCES

Bakker, J. M.; R. Barker: R. Meinzen-Dick: and F. Konradsen, eds. 1999. Multiple uses of water in irrigated areas: A case study from Sri Lanka. SWIM Paper 8. Colombo, Sri Lanka: International Water Manage­ment Institute.

Christensen. T. H. 1984. Cadmium soil sorption at low concentrations: Effect of time, cadmium load, pH and calcium. Water, Air and Soil Pollution 21: 105-114.

Christensen, T. H. 1989a. Cadmium soil sorption at low concentrations: VIII. Correlation with soil param­eters. Water. Air and Soil Pollution 44: 71-82.

Christensen, T. H. 1989b. Cadmium soil sorption at low concentrations. Technical university of Denmark. Polyteknisk forlag, Anker Engelundsvej, 2800 Lyngby. Denmark.

Department of Water Affairs and Forestry. 1996a. South African Water Quality Guidelines. Volume 8, Field guide. First Edition. Department of Water Affairs and Forestry. Private bag X313, Pretoria, South Africa.

Department of Water Affairs and Forestry (DWAF). 1996b. South African Water Quality Guidelines. Vol­ume 4, Agricultural Use: Irrigation. Second Edition. Department of Water Affairs and Forestry. Private bag X313, Pretoria, South Africa.

European Union. 1986. Limit values jar concentrations oj heavy metals in soil. European Union Council directive of 12 June 1986.(86/278jEEC)

FAa. 1992. Wastewater treatment and use in agriculture. FAa Irrigation and Drainage Paper no.47.

Irwin, R. J.; M. VanMouwerik; L. Stevens; M. D. Seese; and W. Basham. 1997. Environmental Contami­nants Encyclopedia. Fort Collins, Colorado: National Park Service, Water Resources Division. Distrih­uted within the federal U.S. Government as an electronic document.

Jensen, P. K.: W. van der Hoek; F. Konradsen: and W. Jehangir. 1998. Multiple use of irrigation water, in Punjab. Sanitation and water for all. 24th WEDC conference. Islamabad, Pakistan. 1998. Proceedings not published.

Lee, S.; L. Chang; C. Chen; M. Lui; and L. Tsai. 1998. Development of soil metal criteria to preserve groundwater quality. Water Science and Technologyol,

US-EPA. 1990. WaleI' quality standard jar wetlands. Office of Water Regulations and Standards (WH-585). EPA/440/S-90-0 II.

van der Hoek, W.; F. Konradsen; and W. A. Jehangir. 1999. Domestic use of irrigation water: health hazard or opportunity? International Journal of Water Resources Development 15: 107-119.

37

I

38

WHO. 1989. Health guidelines for use of wastewater agriculture and aquaculture. WHO Technical Report

Series no.778. Geneva: World Health Organization.

WHO. 1993. Guidelines for drinking water quality, volume 1 recommendation. WHO. Geneva.

-port

Case Study in Pakistan:

Water Quality and Health Impacts of Domestic Use

of Irrigation Water

Report compiled by Peter K. Jensen, IWMI HQ, Sri Lanka

BACKGROUND AND RATIONALE

The domestic users of irrigation water currently face two simultaneous problems: a depleting quantity and quality of their drinking water resources. Not only do national and international policies encourage irrigation departments to diminish the availahle water in irrigation systems to optimize yield from the national water resources, but the available irrigation water' is of an inferior quality as a result of intensified use and reuse upstream in the rivers and catchment areas.

A key factor is global urbanization, which causes an enhanced demand for water alloca­tions to cities and industries, thereby increasing competition between the urban and rural sectors. Agriculture and thereby the domestic users in the irrigated areas are bound to lose the battle for the scarce global freshwater resources owing to a lower economic productivity of water (value per drop) than the industry. According to the United Nations Environmental Program (UNEP), irrigation currently accounts for 69 percent of all global water use, while in­dustry and domestic uses consume 23 percent and 8 percent, respectively (UNEP 1996). These figures have to be seen in the light of the 30-year outlook from the UN predicting a 45 percent increase in population and a doubling of industrial water use.

The problem is twofold. More water is needed in cities because of expanding popula­tions as well as industries. On the other hand, the agriculture sector is under pressure to ac­commodate the need for increased food production. Therefore, a better utilization of the lim­ited water sources is the only solution for most developing countries. Diverting wastewater produced in cities and industries to the agricultural sector is an increasingly used option (Al­Nakshabandi et a1. 1997; Asano and Levine 1986). Wastewater from urban areas contain high amounts of organic and inorganic matter, especially nitrogen, phosphate, and micronutrients that are of utmost importance to agricultural soil. Seen in this light, reusing wastewater not only helps to alleviate water scarcity in arid zones, but could also be a valuable source in recycling the nutrients once exported from the agricultural areas to the cities. The wastewater, however, contains other components, which are hazardous to human health, especially a high content of pathogens discharged with domestic sewage and toxic compounds, such as heavy metals associated with industrial wastewater (Blumenthal et a1. 1991). The irrigation water

39

40

, -~~,----------_.

available to the rural domestic user should therefore, in many cases, be regarded as diluted sewage.

Recognizing the reuse of urban wastewater mixed with other sources of irrigation water, calls for a precise knowledge of the health effects on humans. This knowledge is currently lacking (Ault 1981). Numerous studies have been carried out into different aspects of reusing wastewater for agricultural purposes (Biswas 1993). However, these studies and guidelines have focused on the occupational health hazards to farmworkers irrigating with wastewater and the effects of aerosol contamination on people living in or next to areas (mainly golf courses) where wastewater is applied by sprinkler irrigation (FAO 1992; Shuval et a1. 1986; WHO 1993). None of the guidelines or investigations considers possible domestic uses of irrigation water in irrigation schemes in the developing countries. It is assumed that the water is used strictly for agricultural purposes and that alternative sources of water are available for other uses, including domestic use (WHO 1989; FAO 1992).

Water quality monitoring is well established in the developed world. However, a discus­sion regarding the suitability of different bacteria as indicators of fecal contamination has been going on for some years and problems arise especially when monitoring methods have to be designed made for the tropics. The tradition in temperate zones of the world has been to use a total coliform bacterial count as a fecal pollution indicator, and is proposed in the interna­tional guidelines (ibid.). But investigations have shown that they are less suitable in a tropical climate due to the possibilities of after-growth outside the host organism (Gleeson and Gray 1997). Therefore, researchers are turning towards the use ofthe fecal indicator bacteria E. coli, although there is evidence that a possible after-growth can take place in an aquatic environ­ment under favorable conditions (high temperature and nutrients levels) (ibid). But E. coli is widely recognized as the best fecal indicator for field-testing, due to the simple, fast, and rela­tively cheap analyzing technique. However, it has to be borne in mind that lack of E. coli in a water sample does not directly indicate that the water is free of contaminants; many helminths and viruses are able to survive for long periods of time after bacteria like E. coli have perished (ibid.). There is however still a lack of knowledge on how E. coli behaves under tropical aquatic conditions, and on how to identify the association between the known parameters that could influence the survival/die-off of the bacteria.

The literature shows there are certain parameters that can influence the survival rate of E. coli. The most important are pH, dissolved oxygen (DO), temperature, turbidity, salinity, nitrate, nitrite, ammonium, phosphorus, and Biological Oxygen Demand (BOD) (Gleeson and Gray 1997; Davies and Evison 1991; Joyce et al. 1996; Barcina et al. 1989; Reed 1997). Most of these parameters have been identified under controlled laboratory experiments, and the rela­tive importance o~ the different parameters among themselves in a tropical climate has not been looked at. The task of doing so is very difficult, but may only be done via a computer model that is capable of calculating the interaction of chemical and physical parameters over a period of time in a system. Calibrating such a model with actual measurements from an irri­gation system will therefore give a more in-depth understanding of which parameters have a direct influence on the pathogenic survival in a tropical irrigation canal. This will not only allow prediction of the impact of an additional wastewater introduction to an area but will also make it possible to assess the impact the different irrigation management practices like wet! dry irrigation, demand-based irrigation, etc. (water availability and retention time in the sys­tem) could have on the water quality, and to evaluate different drinking water treatment sce­narios (use of stabilization ponds, sand filters, etc.).

The preliminary results show that there are clear differences in the contamination levels at different sources in the villages. Where the seepage water is nearly free of E. coli (1-10 CFU/lOOml.) the tank and canal water show high numbers of E. coli 102

_ 105 CFU /l 00 ml. Regarding the in-house testing of drinking water containers, a heavy contamination of the drinking water (10 1_105 CFU/lOO ml.) is found to be taking place within the household itself. Comparisons of results with the epidemiological study have not yet been made due to the limitedmonitoring period.

OBJECTIVES

Development Objective

To reduce the incidents of water-related diseases in areas where people use irrigation water for domestic purposes.

Immediate Objectives

i. To assess the microbiological water quality in an irrigation scheme in relation to drinking water sources, human behavior, and water storage procedures.

ii, To investigate and predict the changes in the microbiological water quality within an irrigation system, by use of a one-dimensional computer model.

m. To determine the association between human health and the microbiological water quality of the irrigation water used for drinking purposes.

METHODS

Study Area

The Hakra 6R Distributary is the sixth largest distributary in Pakistan located in southern Punjab (close to the Indian border) on the edge of the Thar desert. Due to its location, the area has very limited natural water resources and an extreme climate. The temperature ranges from 0 °C in January to 46°C in July and the average annual precipitation is 196 mm. The groundwater in Hakra 6R area is brackish and not suitable for drinking or irrigation and the inhabitants are totally dependent on irrigation canal water for all water uses (uz Zaman and Bandraragoda 1996).

Hakra 6R has 78 villages with a population of approximately 136,000. Hakra 6R is a very poor area with the population dependent only on cultivating low-value crops like sugarcane, cotton, vegetables, and wheat. The head end of the distributary is seriously waterlogged and partly unsuitable for agriculture (ibid.).

41

42

The total length of the system is 135 km (ibid.). The distributary receives its water from Sulemanki headwork from where irrigation water is distributed to the different systems in South Eastern Punjab. The inflow to the headwork comes partially from Sutlei river that originates in India and partially from a big canal connected with Ravi river. The Ravi river is receiving all wastewater from the city of Lahore, situated about 250 km upstream (see map 1).

Two hundred households in 10 of the 78 villages were randomly selected (see map 1) and 5 households with different drinking water sources in each village were selected for sam­pling drinking water from the container inside the household.

Table 1. Sources for drinking water.

Village no. 149 98 119 138 118 111 438 129 131 428

Location (head, middle, tail) H H M M M M T T T T

No. of households in sample 11 29 22 15 16 29 9 27 9 33

No. of persons 86 222 150 116 115 260 70 222 63 231

Use of drinking water sources (% of households in each village) -_._-------~-_._~-_ _----~-_._---------_ .-------~--~,-_._._--~._----, "-----~~~-_.._.__.... ..__ .•.,._- .._-_._----,....

Water tank 0 0 0 7 0 17 44 26 0 3

Seepage from tank/canal/fields 100 100 55 93 66 73 66 59 78 97

Water course (direct) 0 0 0 0 0 10 0 0 0 0

Water supply scheme 0 0 45 0 44 0 0 0 0 0

Open well 0 0 0 0 0 0 0 15 22 0

All villages in the area have the same layout (see map 2). The center of the village is a big square where the open village tank is located. The village tank is filled weekly from the watercourse, which runs parallel to the village boundary. Many households are connected via small PVC pipes inserted directly into the tanks. In the vicinity of most tanks there is a well, which is directly connected to the tank by an underground drain, and from which water is drawn manually. Shallow groundwater/seepage is drawn from beneath the water tank at the village boundary adjacent to the agricultural field, or next to the canals. Seepage water is taken from a depth of 1-4 m from the ground surface. It is drawn either by hand pumps on-site or via pipes connected to individual households. The open wells also utilize the seepage water at various places.

Two villages receive water from public water supply schemes. One village has facilities of slow sand filtration and chlorinating (118/6R). The other has a partially filled slow sand filter, which is basically a pond with very small retention time (l19/6R).

All the drinking water sources originate from the irrigation water in Hakra 6R Distribu­tary, either directly or indirectly, by exploiting seepage water. Thus, the initial water quality in the distributary will affect all the domestic water sources mentioned above.

KILOMETERS

KILOMETERS

60 !

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20 !

\.. }.

LAHORE !. '/

r' (

I" ! ( ....F) r'--­

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/

HAKRA 6R DISTRIBUTARY

Map 1. Layout of Hakra 6R.

43

44

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Assessing the Water Quality

Microbiological tests will be carried out at all the identified drinking water sources in the vil­lages and the 50 identified household containers. This will make it possible to evaluate whether the contamination found in the storage containers originates from within or outside the house­hold. It will also establish whether different storage practices have an influence on the con­tamination level, storage in special/traditional containers, etc. The types of E. coli present in the samples will also indicate if E. coli is capable of causing a health risk, i.e., some strains of E. coli like E. coli 015] have proven to cause diarrhea (Greenwood 1992). The testing for virulence genes cannot be carried out in the field; therefore, isolated E. coli will be brought to KVL for analysis.

Since no continuous water supply is normally present in irrigation areas, the study will investigate what effects the storage of drinking water in village tanks has on the microbiologi­cal water quality. Does it have a positive effect (bacteria die-off due to retention time/tempera­ture and sunlight exposure)? Or does it have a negative effect due to external contamination from air deposits, inflow of wastewater to the tanks, regrowth, etc.? Evaluation will also be carried out of different drinking water treatment/storage scenarios at village level (slow sand­filtration, chlorination, or controlled seepage).

Modeling

This part will monitor/model the changes in the water quality down through the canal system and investigate possible associations between the inflow water at the head of the system and the actual contamination levels found in the households. This will not only allow prediction of the impact of an additional wastewater introduction to the area but will also give a more in­depth understanding of the parameters that have a direct influence on the survival and re­moval of fecal bacteria in tropical aquatic systems.

The model will use the intensive campaign measurements for calibration purposes and the less complex daily measurements for extrapolations between the campaigns, enabling simu­lations of the water quality in the entire study period. Modeling based on calibration from actual measurements will make it possible to assess impact of the different irrigation manage­ment practices such as wet/dry irrigation and demand-based irrigation. All these practices will affect the water availability in the system and thus the irrigation water retention times and flow rates.

Association between Water Quality and Human Health

The association between irrigation water quality and human health among the nonagricultural water users in Hakra 6R will be established with statistical tools. This part of the study will be done in close collaboration with the simultaneously ongoing epidemiological study carried out by IWMl. The epidemiological study will monitor the 200 selected households for a 1­year period to document the occurrence of waterborne diseases. The relation between the presence of bacterial indicators in drinking water sources/containers and the occurrence of waterborne diseases, especially diarrhea, within the different households will be studied. Quantities of water available, sanitation practices, and hygienic behavior will be included as

45

46

<r ••_..,....,.. 1IIIi

the main potential confounding variables. Further, a comparison between the two villages with

a piped drinking water system (especially no. 118 with a chlorinated drinking water system),

and the rest of the study area will be made. The purpose of this is to see if the direct use of

irrigation water for drinking purposes has a significant impact on the health status of the house­

holds.

PROJECT PLAN

Set out below is the methodology and predicted outcome of the study for each of the objec­tives described.

Studies Included under Objective I

1. Assessment of the presence of E. coli in all drinking water sources and in house­

hold containers in the selected villages.

2. Assessment of the water quality changes in the village tanks between fillings.

Method Used

Ia) Every week, water samples will be taken from all the identified drinking water sources in

the villages plus the fifty selected household storage tanks/containers. The storage proce­

dure and type of storage container within the individual household will be identified and reg­

istered at the time of sampling. The samples will be analyzed for enumeration ofE. coli. Samples

will be taken in 150 ml. sterile sampling bags. If chlorine is present in the water a dechlorinat­

ing agent will be added. The transport time from the first sample until filtration in the labora­

tory will not exceed 4 hours (Bartram and Balance 1996). The sample will be analyzed via filtra­

tion technique on a Milipoore 0,45 mm membrane filter. The filter is then placed on a m-Coliblue 246 agar, a E. coli specific selective agar, and incubated for 24 hours at 35°C, for enumeration

of E. coli (HACH 1997). Isolates of E. coli will be tested in Denmark for violence genes by

colony hybridization method or PCR techniques.

The results found will be statistically investigated to see if there are any significant

differences in the E. coli level, between villages and households with different water treat­

ment/storage practices.

Ib) Five randomly selected tanks will be monitored daily in the 7-day period between

fillings, or until the tank is refilled. This will be done once per selected tank during the wet and

dry seasons. The time of each filling and water levels before and after filling will be noted and

measured. For estimation of seepage losses and concentration changes the precipitation and

evaporation (multiplied by a coefficient to correct for tank structure) will be measured by pan.

This will be done at a central place in Hakra 6R. Samples will be analyzed for E. coli, electrical

conductivity (EC), pH, DO, temperature, turbidity, fluoride, sodium, total-hardness, iron, salin­

ity, nitrate, nitrite, ammonium, phosphorus, BOD, and COD.

01

taken. A (deioniz

pre froze

within 4

and ana

using el

using a

(HACH

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One sample of the inflow water at filling and a daily sample from the tank itself will be taken. At each sampling site 1.7 liters of water will be collected in prewashed plastic bottles (deionized water). After filling the bottles will be immediately put into cool boxes containing prefrozen elements and transported to the laboratory. lfthe inorganic testing cannot take place within 4-6 hours after sampling, they will be preserved with acid. For bacteriological sampling and analysis see la. Parameters such as pH, EC, sodium, and DO will be measured on-site using electrodes. The remaining parameters will be measured in the field-station laboratory, using a HACH spectrophotometer DR/2010 or titration according to the standardized method (HACH 1997).~

Predicted Outcome of Study

la) The results will indicate the water quality of the different sources in the villages, allowing a possible assessment of the contamination level the selected households are exposed to via their drinking water source, and if the E. coli in itself poses a health risk. Further, it will be possible to estimate the in-house contamination and to see the difference in storage practices and storage containers (clay/brass). An assessment of different drinking water treatment sce­narios in an irrigation scheme will be done to investigate if it is desirable to use high-tech solutions, such as chlorination, or traditional solutions like utilization of seepage water.

lb) The monitoring will show the variation of water quality in the village tank between the fillings. This would make it possible to assess if different factors like sunlight and tem­perature have an effect on the die-off or possible multiplication of the bacteria, thus indicating the die-off rate in the system.

Studies Included under Objective II

1. Monitoring the water quality changes in the canals.

2. Modeling the microbiological changes in the system.

Method Used

IIa) This study consists of daily monitoring and four measuring campaigns. The campaigns have to be carried out every 3 months to cover different climatic and agricultural seasons. Each monitoring campaign will last 24 hours. Measuring stations will be set up at seven struc­tures (canal intersections) in the system where a half-hourly recording of water level will take place. At each station the water quality will be measured four times during the campaign (pa­rameters as lb). The structures from where the measurements are taken will be calibrated to establish the H/Q (water level/flow) relationship for each structure.

Pretesting will make it possible to construct a sampling technique whereby one sample will represent the concentration in the cross section of the water body (Bartram and Balance 1996). The monitoring of DO, pH, and turbidity will take place both upstream and downstream from the structure, due to the total mixing at downstream. For sample size, handling, and ana­lyzing technique see lb.

47

48

A daily sample will be taken from Hakra 6R at one of the measuring stations. This will include: E. coli, pH, DO, temperature, and turbidity. At two places in the system the water level will be recorded daily together with rainfall, evaporation, temperature, and solar influx data from a meteorological station to be set up in the middle of Hakra 6R.

lIb) The model to be used is the Mike II surface water quality model from Danish Hy­draulic Institute. The input to the model will be the data collected in lIa. Blue prints of the Hakra 6R Distributary will be obtained from the Irrigation Department in Bahawalnagar, to give the dimensions for cross sections and distances within the system. The two practices, wet/ dry irrigation~ and demand-based irrigation will be tested by creating scenarios where the spe­cific type of irrigation is carried out in the area using the background data from the calibrated model.

Predicted Outcome of Study

lIa) From the four campaigns it would be possible to have a 4x24 hour in-depth knowledge of how the canal system affects the different parameters in question, and to determine the differ­ence in the water quality at different water flows, temperature, sun light exposure, etc.

lIb) The model will not only allow prediction of the impact of an additional wastewater introduction to the area but will also give a more in-depth understanding of which parameters have a direct influence on the pathogenic survival in a tropical irrigation canal. An evaluation will be made of the different irrigation management procedures in respect to their treatment effect on polluted irrigation water.

Study Included under Objective III

IlIa) Determine the association between human health and the microbiological water quality of the irrigation water used for drinking purposes.

Method Used

IlIa) Statistical analysis using SPSS' 6.0 (Nurusis 1993). Statistical software for epidemiologi­cal analyses, will correlate the E. coli levels found in the drinking water sources to the diar­rhea cases in the households, obtained in the epidemiological study. The epidemiological data have been obtained via weekly visits to the households and with a week recall period to quan­tify the daily occurrence of diarrhea cases for the different family members.

Predicted Outcome of Study

IlIa) Via the statistical results, it will be possible to determine if there is a connection between the irrigation water quality/drinking water source and the diarrhea cases in the households. It will also be possible to detect if there is a difference in the disease pattern among the villages for those with water supply schemes and those without. Further, it will be possible to deter­mine if the key contamination source is at the source or in the household itself.

OUTPUTS AND PROJECT BENEFICIARIES

The overall beneficiaries of the project will be the poor farming communities living in the irri­gation areas in the developing countries, whose drinking water resources are under threat by factors beyond their influential sphere. The project target group will therefore be water supply and irrigation system planners in the tropics, at both national and international levels, and researchers who are investigating public health and pathogens' survival in tropical aquatic systems, and who have a direct influence on the overall water resources management. On the basis of the identification of the important parameters, and on the recommendations given regarding health impact minimization weighed against the feasible low-cost technologies for treatment and irrigation management, these people will be able to incorporate the needs of the domestic users in their future planning/research.

REFERENCES

Al-Nakshabandi, G. A.; M. M. Saqqar; M. R. Shatanawi; M. Fayyad: and H. Al-Horani. 1997. Some environ­mental problems associated with the use of treated wastewater for irrigation in Jordan. Agricultural

Water Management 34:81-94.

Asano, T.; and A. D. Levine. 1996. Wastewater reclamation, recycling and reuse: past, present and future. Water Science and Technology 33(10-11): 10-14.

Ault, S. K. 1981. Expanding non-agricultural uses of irrigation [or the disadvantaged: Health aspects.

Barcina. I.; J. M. Gonzales; J. Iriberri; and L. Egea. 1989. Effect of visible light on progressive dormancy of Escherichia coli cells during the survival process in natural fresh water. Applied and Environmental

Microbiology 55( I):246-251.

Bartram, J.; and R. Balance. 1996. Water quality monitoring. London: E & FN SpaN.

Biswas, A. K. 1993. Wastewater reuse, environment and health. In CIHEAM, Advanced short course on

sewage treatment practices-manugement for agriculture use in the Mediterranean countries, pp. 250­27 I. Cairo, Egypt.

Blumenthal, U. 1.; B. Abisudjak; E. Cifuentes; S. Bennett; and G. Ruiz-Palacios, 199 I. Recent epidemiologi­cal studies to test microbiological quality guidelines for wastewater use in agriculture and aquaculture. Public Health Review 19: 237-242.

Davies, C. M.; and L. M. Evison. 199 I. Sunlight and the survival of enteric bacteria in natural waters.

Journal oi Applied Bacteriology 70:265-274.

FAa. 1992. Wastewater treatment and use in agriculture. FAa Irrigation and Drainage Paper No.47. Rome: FAa.

Gleeson, c.; and N. Gray. 1997. The coliform index and waterborne disease. London: E & FN SpaN.

Greenwood, D.. ed. 1992. Medical Microhiology. Fourteenth edition. ELBS.

HACH. 1997. Water analysis handbook. Loveland, Colorado, USA: HACH Company.

Joyce, T. M.; K. G. McGuigan; M. Elmore-Meegan: and R. M. Conroy. 1996. Inactivation of fecal bacteria in drinking water by solar heating. American Society for Microbiology 62:399-402. New York: The Agricultural Development Council Inc., 86p.

Nurusis, M. J. 1993. SPSS"for Windowso Base system user's guide release 6.0. Chicago: SPSS Inc.

49

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50

Reed. R.H. 1997. Solar inactivation of fecal bacteria in water: The critical role of oxygen. Letters in Ap­plied Microbiology 24:276-2RO.

Shuval. 1-1.1.: A. Adin: B. Fattal; E. Rawitz; and P. YekutieI. 1986. Wastewater irrigation in developing countries: Health effect: and technical solutions. World Bank Technical Paper No. 51. Washington D. C.: World Bank.

UNEP (United Nations Environmental Program). 1996. World resources 1996-97: The urban environ­ment. New York: United.Nations Environmental Program.

WHO. 1989. Health guidelines for use of wastewater agriculture and aquaculture. WHO Technical Report Series no.778. Geneva: WHO.

WHO. 1993. Reuse of community wastewater: Health and environmental protection-research needs. Dis­cussion Paper 6. Community Water Supply and Sanitation Unit. Geneva: WHO.

lIZ Zaman, W.: and D. J. Bandraragoda. 1996. Government interventions in social organization for water resource management: Experience of a command water management project in the Punjab, Pakistan. Report no. R-14. Lahore. Pakistan: International Irrigation Management Institute.

tv

Tab

le 5

. A

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ge a

nd s

tand

ard

devi

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n pa

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7.42

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0.

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0.69

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I

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40.4

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27)

7.6

(0.4

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0.16

(0.1

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1.14

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0.

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(0.0

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147.

83

( 150

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Lag

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66.9

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57.2

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63

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0.27

(0

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36

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0.02

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91.5

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ephe

lom

etri

c tu

rbid

ity

unit.

** T

eU =

Tru

e co

lor

unit.

NH

) (m

g/!)

S

uspe

nded

so

lids

Tot

al

hard

ness

Alk

alin

ity

CI

(mg/

!)

F

(mg/

!)

Na

(mg/

l) K

(m

g/!)

SA

R

Irri

gati

on (

Lun

ugam

weh

era)

0.

08

(.06

) 15

.5

(7.6

9)

120.

33

(24.

92)

147.

67

(32.

07)

18

(7.3

4)

0.2

(0.0

6)

20.4

3 (4

.79)

3.

67

(0.5

8)

26.5

2 (5

.77)

Dra

inag

e 0.

53

(.46

) 12

7 (9

9.23

) 54

0.5

(515

.07)

21

1.67

(60.

59)

447.

83

(535

.58)

0.

36

(0.1

0)

155.

35

(97.

05)

6 (3

.33)

11

0.42

(3

3.26

)

Lag

oon

(Em

bili

kala

) 0.

63

(.61

) 18

3.92

(149

.12)

33

7.09

(9

6.26

)

206.

73

(30.

10)

282.

55

(147

.06)

0.

31

(0.0

5)

161.

06

(78.

56)

7.38

(4.5

0)

125.

93

(40.

97)

• :'-

",'