WATER ALLOCATION POLICY MODELING FOR THE DONG NAI RIVER BASIN: AN INTEGRATED PERSPECTIVE1

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION DECEMBER AMERICAN WATER RESOURCES ASSOCIATION 2006

WATER ALLOCATION POLICY MODELING FOR THE DONG NAI RIVER BASIN: AN INTEGRATED PERSPECTIVE1

Claudia Ringler, Nguyen Vu Huy, and Siwa Msangi2

ABSTRACT: Recent water sector reforms and increased scarcity and vulnerability of water resources, combined with declining public funding available for large scale infrastructure investment in the sector, have led to a greater awareness by the Gov- ernment of Vietnam for the need to analyze water resource allocation and use in an integrated fashion, at the basin scale, and from a perspective of economic efficiency. In this study we focus on the development, application, and selected policy analyses using an integrated economic hydrologic river basin model for the Dong Nai River Basin in southern Vietnam. The model framework depicts the sectoral structure and location of water users (agriculture, industry, hydropower, domestic, and the environment) and the institutions for water allocation in the basin. Water benefit functions are developed for the major water uses subject to physical limitations and to constraints of system control and policy. Based on this modeling framework, we will analyze policies that can affect water allocation and use at the basin level, including both basin-specific and general macroeconomic policies. (KEY TERMS: river basin modeling; watershed management; irrigation; optimization; water markets; economic development.)

Ringler, Claudia, Nguyen Vu Huy, and Siwa Msangi, 2006. Water Allocation Policy Modeling for the Dong Nai River Basin: An Integrated Perspective. Journal of the American Water Resources Association (JAWRA) 42(6):1465-1482.

INTRODUCTION

Fresh water, essential to sustain life, development, and the environment, is an increasingly vulnerable resource in Asia, where population and economic growth creates serious challenges for meeting water demands for food requirements and other uses. Asian countries face rising competition for water resources from rural and urban sectors for agricultural, industrial, and household uses, combined with declining investments in infrastructure. Water quality is increasingly threatened as agricultural, industrial (including rural industrial), and domestic users in increasingly crowded watersheds compete for scarce water supplies. In this water scarce and often polluted environment, it is essential to understand the impacts of specific policy alternatives for water allocation among these users: whether they are feasible, what they will cost, and how they will affect water users and the overall prospects for agricultural production and economic growth.

Water policy analysis requires the application of comprehensive policy analysis tools that need to be adapted and expanded depending on the river basin in question. Economic optimization models that opti- mally allocate water based on an objective function and accompanying constraints, along with hydrologic simulation models and a representation of institutional rules, can be complementary tools to traditional river basin simulation models to address problems related to the competition over scarce water resources and the design and assessment of alternative systems

1Paper No. 05160 of the Journal ofthe American Water Resources Association (JAWRA) (Copyright 0 2006). Discussions are open until June 1,2007.

2Respectively, Research Fellow, International Food Policy Research Institute, 2033 K Street, NW, Washington, D.C. 20006; Project Engi- neer and Member, Dong Nai Basin Planning Management Council, Sub-Institute for Water Resources Planning, Ho Chi Minh City, Vietnam; and Postdoctoral Fellow, International Food Policy Research Institute, 2033 K Street, NW, Washington, D.C. 20006 (E-Maimingler: [email protected]).

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RINGLER, VU HUY, AND MSANGI

of water allocation. In this study we take a holistic approach in analyzing the complexities involved in water allocation to generate options for water policy reform in the Dong Nai River Basin for optimal uti- lization that is also sustainable, efficient, and equitable (Rogers and Fiering, 1986; McKinney et al., 1999). The alternative policy analyses presented here have been developed with and can support the recent- ly established Dong Nai River Basin Planning Man- agement Council. The policy scenarios developed can help policy makers and basin water planners gain a better understanding of water availability, demand, and its value in various uses; provide insights into the role of alternative policy instruments in alleviating likely future water shortages; and thus contribute to more efficient and sustainable allocation of scarce water and financial resources across irrigation, hydropower development, and urban demands.

We begin by briefly describing the river basin stud- ied, introducing the modeling framework and data used, and presenting a baseline and optimization

results. We use alternative scenarios to evaluate changes in irrigation efficiency, the role of water use rights systems, and to study the impact of changes in national level input price subsidies on the basin economy.

Background

The Dong Nai River Basin (DNRB) is the largest national river basin and economic center of Vietnam. For administrative and planning purposes, a series of several smaller coastal basins are combined with the Dong Nai basin proper adding to a total surface area of 48,471 km2 within Vietnam, or about 15 percent of the country's land surface area (Figure 1). Total discharge is estimated at 47.065 km3, including about 6 to 7 k m 3 of inflows from the Mekong River. Rainfall averages 2,000 mm but can be as low as 700 mm in some coastal areas. The DNRB has five major rivers: the Dong Nai mainstream, the Be, the Sai Gon, and

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Figure 1. The Dong Nai River Basin.

1466 JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION

WATER ALLOCATION POLICY MODELING FOR THE DONG NAI RIVER BASIN: AN INTEGRATED PERSPECTIVE

the La Nga as major tributaries, and the Vam Co Dong system that joins the Dong Nai just before the outlet into the South China Sea. There is one major interbasin transfer to the Cai Basin in the coastal area (within the Dong Nai basin planning unit) of approximately 20 m3/sec and a second transfer is under construction (Figure 2).

The DNRB ranks second in hydropower potential in the country, and in 2000, total installed hydropower capacity reached 1,182 MW, with average annual power production of 4,881 GWh. Total investment costs of existing hydropower projects are estimated at (U.S.) $1.1 billion, including Ham Thuan-Da Mi, Thac Mo, and Tri An reservoirs. The basin also includes

v)

0 E

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION 1467

c .- (I)

Fs"

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Dau Tieng, the largest irrigation reservoir in Viet- nam, and several more reservoirs are under construction.

The basin includes 10 provinces and Ho Chi Minh City (HCMC). As can be seen in Table 1, the DNRB is highly developed, with a relatively low share of agricultural gross domestic product (GDP), relatively high income per capita, and a high population density compared with other regions in Vietnam. Although on average the basin population of 14 million people is relatively affluent, there are several poor districts and provinces, including large areas in Ninh Thuan and Binh Phuoc provinces and rural districts in Binh Thuan, Dak Lak, and Lam Dong provinces. While the share of agriculture in total GDP has been declining over time, the agricultural sector in the basin is highly diversified and dynamic; its products range from basic staples like rice and maize to raw materials for the local industry, including rubber and sugarcane, to high-value crops like coffee, flowers, fruit, pepper, tea, and vegetables.

On the institutional side, the 1999 Water Resources Law establishes that water should be allocated fairly and reasonably on a river-basin scale; that priority in use in both quali ty and quant i ty is accorded to drinking water (Article 20); and t h a t water use and wastewater discharge a re to be licensed by provincial government authorities (People’s Commit- tees). In 2001 the Ministry of Agriculture and Rural

Development established a Basin Planning Manage- ment Council for the DNRB that currently is focusing chiefly on river basin planning.

MODELING FRAMEWORK

The model developed for the DNRB draws on previ- ous economic hydrologic modeling of the Maipo River Basin in Chile (Rosegrant et al., 2000). It belongs to the class of integrated economic hydrologic river basin models and includes hydrologic, economic, and institutional components. The model focus is on the economic component. The river basin model is developed as a node l ink network, which is a n abstracted representation of the spatial relationships between the physical entities in the river basin. Nodes represent river reaches, reservoirs, and demand sites, and links represent the connections between these entities (Figure 2). Inflows to these nodes include runoff from the headwaters of the river basin as well as local runoff. Flow balances are calculated for each node at each time period, and flow transport is calculated based on the spatial linkages in the river basin network.

For policy analysis purposes, provinces are considered the major modeling units in the river basin model. Agricultural demand sites a re delineated

TABLE 1. Economic Indicators for the Provinces in the Dong Nai River Basin.

Gross Share Share Monthly Irrigated Agriculture Industrial Average

Land Area Area Population GDP GDP GDP Income

Province (ha) (ha) (‘000) (US$ million) (percent) (percent) (@cap) 2000 1999 2000 1999 1999 1999 1999

Binh Duong Binh Phuoc Binh Thuan

Ba Ria-Vung Tau Dak Lak

Dong Nai HCMC Long An Lam Dong Ninh Thuan Tay Ninh

TOTAL

269,555

685,598

783,809

190,000

388,909

589,474

209,505

188,153

976,440

336,006

402,8 12

5,020,261

20,693

24,844

71,231

20,762

12,097

59,188

69,742

143,147

88,245

42,307

199,619

751,874

738

687

1,066

823

99

2,039

5,222

810

1,038

516

979

14,018

376

114

141

3137

433

878

5036

414

222

103

268

11,123

19

65

47

5 71

24

2

53

60

53

45

14

55

8

21

82

8

50

44

19

14

13

19

51

29.1

23.6

19.9

32.2

27.7

31.9

59.3

23.2

29.1

16.6 22.2

Note: GDP and income refer to the entire province, not just basin area. References: Land area: Sub-NIAPP; gross irrigated area: adjusted from SIWFtP population and GDP: various statistical yearbooks; income

per capita: GSO (2001).

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W A T E R ALLOCATION POLICY MODELING FOR THE DONG NAI RIVER BASIN: AN INTEGRATED PERSPECTIVE

according to 37 subcatchments and administrative boundaries, resulting in 60 irrigation demand sites. For domestic uses, adjacent districts have been sum- marized, yielding 48 domestic demand sites. For industrial water use, 12 demand sites are delineated in provinces with major industrial water use (Ba Ria- Vung Tau, Binh Duong, HCMC, and Dong Nai) and provinces with lower industrial development (Binh Thuan, Long An, Ninh Thuan, and Tay Ninh). The model also simulates operation of the major existing reservoirs for hydropower production, irrigation, and flood control.

Thematically, the modeling framework includes three components: hydrologic components, including the water balance in reservoirs, river reaches, and crop fields; economic components, including the calcu- lation of benefits from water uses by sector, province, and demand site; and institutional rules and economic incentives that affect the hydrologic and economic components. Water supply is determined through the hydrologic water balance in the river system, and water demand is determined endogenously within the model based on functional relationships between water and productive uses in irrigated agriculture, domestic and industrial uses, and hydropower. Water supply and demand are balanced based on the objective of maximizing economic benefits t o water use. Environmental requirements to control saltwater intrusion are included as flow constraints. The time horizon of the model is one year with 12 periods (months).

Hydrologic Component

Hydrologic relations and processes are based on the flow network. They include flow routing and balance from river outletslreservoirs to crop fields and domestic and industrial demand sites; return flows from irrigated areas and urban-industrial areas; reservoir releases; instream water uses; and ground water.

The basic flow balance at a river node in the basin network is calculated for every month as

flow-downstream = flow-upstream + local-drainage + returnjlows - withdrawals - (evaporation) losses (1)

Water balances are also calculated for reservoir and ground water storage. For surface reservoirs, net evaporation (calculated as monthly surface evaporation subtracting monthly precipitation on the reservoir) is included in the reservoir mass balance equation.

The rainfall-runoff process is not included in the model. It is assumed that runoff starts from rivers and reservoirs. Effective rainfall for crop production is calculated outside of the model and included into the model as a parameter. As ground water data were scarce, the exploitation capacity of shallow ground water was included and withdrawal estimates as available, but ground water was not modeled separately.

Source flow was determined by the hydrology divi- sion of SIWRP (Sub-Institute for Water Resources Planning, HCMC) based on a rainfall-runoff model called RRMOD for 1978-1998 for a total of 37 river nodedreaches. Together with the withdrawal nodes, a total of 82 nodes are included in the model. Total estimated basin discharge amounts to 47.1 km3. As these data are ex-post depletion, estimated actual depletion, just under 4 km3, is added to these observed natural flows. A minimum instream flow requirement for all river reaches in the basin of 10 percent of inflow has been included to guarantee basic river habitat. In addition, estimates for minimum flow requirements to control saltwater intrusion and secure safe drinking water supply for the lower basin, chiefly HCMC, have been included.

Economic Component

The objective of the model is to maximize the annual net profits from water uses in irrigation, households and industries, and hydropower generation. The objective function is formulated as

Max Obj = c VA, + VMm + c W i n + VPpw (2) a m in PW

where VA is the net profit from irrigated agriculture; V M is the net benefit from domestic water use; V I is the net profit from industrial production; V P is the net profit from power production; and a, m, in, p w are the indexes for irrigation, domestic, industr ia l demand sites, and power stations.

Crop Yield Function. To establish a relationship between inputs other than water and crop yield, a quadratic production function is chosen due to its properties of decreasing marginal returns to additional inputs and substitutability of inputs.

The quadratic function is expressed as

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION 1469 JAWRA

RINGLER, Vu HUY, AND MSANGI

where a and y are the input coefficients and x are inputs by crop c. Water inputs in this equation are fixed at the yield maximizing level. To establish a relationship between crop yield and water stress, the crop yield water stress relationship described in Doorenbos and Kassam (1979) and Doorenbos and Pruitt (1977) is used.

y = yst" (1 - ky) * (1 -ETA / ETM) (4)

where y is the actual yield (water-stressed) (mt/ha), ky is the crop yield response coefficient, yst is the non- water stressed yield (mt/ha), from the quadratic production function, ETA is the seasonal actual evapotranspiration (mm), and ETM is the seasonal potential evapotranspiration (mm).

The net profit function for irrigated agriculture is formulated as

VA, = A,,, * y,,, * pc, - (ZC, + mc, + fc, + pee,) - Wa,c * PWC

(5)

where A is the area harvested (ha), W is the irrigation water applied (m3), y is the actual yield from FA0 relationship (mt/ha), pc is the crop price at farm gate ($/t), Zc is the labor cost (family and hired) (MD/ha), mc is the machinerylanimal cost ($/ha>, fc is the fertilizer cost ($/ha>, pec is the pesticide cost ($/ha), p w is the water fee ($/m3), and c is the index for crop.

The parameters for the crop yield function were collected by Sub-NIAPP (Sub-National Institute for Agricultural Planning and Projections) in an exten- sive farm household survey covering 700 households in the 11 provinces of the DNRB, yielding more than 1,600 individual crop level observations. Based on the survey data, crop yield functions were estimated for the major irrigated seasonal crops (bean, maize, peanut, rice, sugarcane, tobacco, vegetables) and perennial crops (coffee, fruit tree, other tree, pepper) in the basin. Paddy and vegetable crops are further subdivided by region into coastal area, mountainous area, and lowland area. Estimated yield functions and production costs are applied to the gross irrigated area for 1999-2000 of 0.759 million hectares.

Domestic Net Benefit Function. The net benefit function for domestic water uses (VM) is derived from

an inverse demand function for water. In a first step, a double log function is estimated by

where mwd is the per capita water demand (m3/cap), '1~) is the constant, 1 is the income ($/cap/month), Pmwd is price paid for water ($/m3), E is the price elasticity of demand, and p is income elasticity of demand.

The inverse of the demand function is then integrated over the space of mwdo - W to estimate the consumer surplus by

urban,rural,pd,pop (1-

where CS is the Consumer Surplus ($ million); mwdo is the per capita normal water demand (m3/cap); Pmwd is the price for water, including urban and rural water and surface and ground water; and urban, pd, rural, pop are indexes for urban/rural parameters, for time period (pd) and population (pop).

The parameters for the domestic benefit function were estimated separately for connected and unconnected households based on the 1995 domestic water demand behavior survey conducted by Gesellschaft fur Klaranlagen und Wasserversorgung Mannheim / Societk Anonyme FranCaise d'Etudes et de Gestion (GKW/SAFEGE, 1996). The survey was done in the 12 inner and four peripheral districts of HCMC. The price and income elasticities estimated were then applied to other districts in the basin, following adjustments for rural-urban shares (to which unconnected and connected parameters were applied, respectively), rural-urban incomes, and rural-urban consumption shares.

Industrial Net Profit Function. A production function approach to industrial water demand, which is conceptually correct given that water is an input to a marketed end product, cannot be realized due to a lack of industrial survey data. Therefore, a synthetic



willingness-to-pay curve is developed based on the observed level of water use and average and marginal water use. Based on a literature review, a price elasticity of water demand of 0.71 is chosen (equal to three times the average price elasticity for connected and unconnected households in HCMC used in the domestic water demand function). Second, the mean contribution of water to production cost was assumed to be 0.05. Based on these data points, the following function can be estimated as

where i w d is the indus t r ia l water withdrawal (rnVmonth) [auailablel, p is the constant, 8 is the price elasticity of industrial water demand [synthe- sized], and Piwd is the industrial water price ($/m3) [auailablel .

Based on the known values of iwd, Piwd and the estimated 8, the constant can be calculated. Equation (9) presents the net benefit function t o increased water use.

where iwdo is industrial withdrawals at normal demand (mYmonth).

For this study, industrial water use was collected from the industrial zones of the four major industrial provinces in the basin (Ba Ria-Vung Tau, Binh Duong, HCMC, and Dong Nai) and from municipal water supply companies in the various basin provinces. This was supplemented with water use estimates based on water use coefficients for industrial products based on Boggs (1995, Table 6).

Hydropower Net Profit Function. To estimate power production, in a first step, power production efficiency is calculated based on daily release and power production data. Profit from power production (VP) is calculated as a linear function, multiplying power production (pow) with the difference between power selling price ( p p ) and power production cost (pc) for each hydropower station

VPPW = Powpw . (PPpw - PCpw) (10)

In addition to the computed efficiency estimates, power production parameters also include operation rules, dead and maximum storage, maximum turbine

flow, and area storage and elevation storage relationships. For analysis purposes, it is assumed tha t hydropower profits accrue to those provinces where the reservoir is located.

The model has been coded in the GAMS modeling language, a high level modeling system for mathemat- ical programming problems. It consists of 50,317 single. equations (rows) and 117,691 single variables (columns) with 185,034 nonzero coefficients. The CONOPT3 solver for highly nonlinear problems has been used to solve the model. It is solved in two stages, using the piece-by-piece approach to solving large nonlinear water resources management models described by Cai et al. (2001).

BASELINE AND OPTIMIZATION RESULTS

The baseline (BAS) attempts to recreate the water allocation and use situation prevailing in 1999-2000. This usually cannot be achieved through full optimization because optimized allocation is based on a partial incorporation of the reality into the modeling framework and because the logic of the modeling approach assumes economic efficiency as the main driving force for water allocation across time and space, with perfect insight and foresight into the scarcity value of water in its various uses. For BAS, water allocations to various sectors a re fixed at observed levels. Full optimization (OPT) presumes an omniscient decision maker, which can be represented, for example, by the Dong Nai River Basin Organiza- tion. However, transaction costs for full optimization of basin resources in the real world would be tremen- dous. For this scenario, irrigated area can range from 0.2 to 1.5 of observed irrigated area, and crop inputs other than water are within a range from 0.8 to 1.2 of average input levels. Domestic demand is within a range of 0.7 to 1.15 of observed demand and industrial demand within a range of 0.5 to 1.5 of actual demand. Reservoir releases operate within operation rules.

Under BAS, total off-stream water withdrawals from surface sources are estimated at 6,157 million cubic meters (MCM), 12 percent of total runoff. Mini- mum flow requirements for drinking water on the Dong Nai and Sai Gon Rivers account for a further 3,469 MCM. Surface withdrawal shares are 89 percent for irrigation, 5 percent for domestic uses, and 5 percent for industrial water uses. In addition, total ground water abstractions amount t o 705 MCM, or 7 percent of total shallow ground water capacity. About 292 MCM are pumped for irrigation, 163 MCM for domestic uses, and 251 MCM for industrial uses. Total power production amounts to 5,287 GWh.



Under the OPT scenario, water can be allocated more freely across sectors following optimization objectives within the bounds specified above and the physical and system control constraints and minimum instream and downstream flow requirements. Under this scenario, surface water withdrawals increase to 6,353 MCM, and ground water pumping increases by 4 percent. Compared to BAS, gross irrigated area under OPT drops by 75,000 ha, a clear reflection of water reallocation out of low value irrigation uses under BAS. The decline is largest for rice crops, but coffee area declines as well. Area under upland crops, on the other hand, increases by 55,000 ha (Figure 3).

=BAS OOPT

600 I - 500

t 400

5 300

m c

4 200

‘E 100 LD

0

I 487 I

192

In 115

Perennial Upland Rice

Figure 3. Changes in Crop Pattern, BAS, and OPT Scenarios

Figure 4 presents the distribution of natural flows, modeled discharge, and estimated water demands (including instream flow demands for drinking water in HCMC) at the basin outlet across the year for the BAS scenario. The graph shows the large variation in flow between the dry and rainy seasons in the basin. The construction of several large reservoirs, which are included in the model simulated flows, has been vital to prevent water shortages in the dry season, as demands surpass natural (prior to storage) flows during February to April by 164 MCM t o 339 MCM. Based on this graph the DNRB as a whole can be characterized as an “open” river basin, as excess water is available over and above all committed legal, ecological, and environmental requirements, even during the dry season. However, the basin will likely soon approach a “semi-closed” state, in which sufficient water resources are available during the rainy season, but off-stream and instream water needs compete with each other during the dry season. In “closed” basins, finally, there is no excess water flow- ing out of the basin; all water resources are committed to use (Keller et al., 2000). The closed state is unlikely to occur in the Dong Nai basin due to the large wet season flows, high storage potential, and ongoing and planned storage construction.

Table 2 presents net profit per hectare and the productivity of irrigation water for irrigated basin crops under BAS and OPT. Net profits per hectare are largest for the category “other tree” (including grapes and mulberry trees) and pepper, followed by tobacco

+Model simulated flow - 3 ~ - Natural flow - Model simulated demand

12000 1

2 8000

E 6000 z ‘CI ‘ 4000 5 g 2000 u,

0 I I I t I I I I I I I I

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Figure 4. Distribution of Natural Flows, Model Simulated Flows and Model Simulated Demands at the Basin Outlet, BAS Scenario.

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WATER ALLOCATION POLICY MODELING FOR THE DONG N A I RIVER BASIN: AN INTEGRATE0 PERSPECTIVE

TABLE 2. Net Profit Per Hectare and Productivity of Irrigation Water by Crop, BAS and OPT.

Profit Per ha BAS OPT

Profit Per m3 BS OPT

Other Tree Pepper TobaccoDX

VegetableHTc VegetableMUAc

Vege tableDXc VegetableHTm

VegetableMUAm

VegetableDXm

VegetableDXu

Fruit tree

VegetableHTu

BeanHT BeanMUA VegetableMUAu PeanutDX MaizeDX

Coffee MaizeHT PeanutHT

RiceHTm

BeanDX

RiceMUAu RiceDXu RiceHTc

Sugarcane RiceDXc RiceMUAc RiceMUAm RiceHTu

9,074

5,654

3,463

2,380

2,248

2,205

2,181

1,406

1,175

1,131

1,069

870

844

801

800

574

438

358

311

261

164

152

129

126

85

81

80

77

53

39

9,238

6,027

3,578

2,629

2,595

2,455

2,475

1,429

1,275

1,211

1,879

911

886

856

855

588

470

505

323

276

128

232

182

205

227

278

222

194

122

147

0.43

1.40

0.39

0.29

0.58

0.36

0.48

1.20

0.26

0.25

0.12

0.29

0.17

0.33

0.31

0.07

0.05

0.06

0.15

0.12

0.03

0.03

0.02

0.01

0.01

0.01

0.01

0.01

0.02

0.01

~~

0.44

1.09

0.40

0.32

0.67

0.41

0.55

1.22

0.28

0.28

0.21

0.31

0.18

0.36

0.33

0.07

0.05

0.06

0.16

0.13

0.04

0.03

0.02

0.01

0.01

0.02

0.01

0.02

0.03

0.02

Notes: DX = Winter-Spring, HT = Summer-Autumn, MUA = Rainy Season; c = coastal area (Ba Ria-Vung Tau, Binh Thuan, and Ninh Thuan provinces; m = mountainous area (Binh Phuoc, Dak Lak, and Lam Dong provinces); u = lower basin (Binh Duong, Dong Nai, Ho Chi Minh City, Long An, and Tay Ninh provinces).

and some of the vegetable crops. Profits per hectare are lowest for sugar cane and some of the paddy crops. At the lower end, there is significant variation in values between the BAS and OPT scenarios, as the flexible adjustment of inputs other than water under OPT helps avoid some of the low crop profits of the BAS scenario. The productivity of irrigation water, defined as U.S. dollar per cubic meter of irrigation water applied, depends on both the profitability of the crop and its need for irrigation water, which is

determined by growing season, growing length, and climatic factors, among others. Baseline results indicate that water productivity is high for vegetables planted in the highland areas and the summer- autumn season. This is because these crops consume very little irrigation water. Among the nonvegetable crops, pepper, other tree, and tobacco stand out as crops with relatively high profit per unit of water con- sumed. Unsurprisingly, water productivity is lowest for sugarcane and various paddy crops.



ALTERNATIVE SCENARIOS

Several policy analysis scenarios are implemented to address concerns regarding some important input parameters raised by members of the basin council. Analyses presented here include variations in irrigation efficiency at the field and primary and secondary canal levels; the impact of alternative water rights and trading systems on farmer incomes; and impacts of fluctuating agricultural commodity prices and national level support price policies.

Irrigation Efficiency and Water Conservation

One important means to save water resources is the improvement of field application efficiency. In the baseline scenario, irrigation efficiency on-farm is estimated at 0.7, that is, 70 percent of the water applied at the field level is used beneficially by plants; and base conveyance and distribution efficiency is 0.5. If the field application efficiency level were increased to 0.9 (and thus overall efficiency to 45 percent), for example, through investments in irrigation technolo- gy in the entire basin, then irrigation profits would increase to 111 percent of OPT levels (an increase of $42 million), and hydropower profits would decline by a very small amount (a reduction of $100,000). Increased on-farm irrigation efficiency allows additional planting of low profit crops, and both irrigated area and ground water pumping would increase. The annual cost of increased on-farm efficiency, not incor- porated here, should not surpass the estimated increase in net benefits from irrigation estimated for this alternative.

When field application efficiency is reduced to 0.5, that is, only half of the water arriving at the field can be used effectively for crop evapotranspiration (and thus overall efficiency is reduced to 25 percent down from 35 percent), then irrigation profits drop to 88 percent of OPT levels. In this case, the relatively more expensive ground water pumping would decline to 69 percent of OPT levels. This decline would be compensated by increased surface water withdrawals.

The Government of Vietnam has undertaken a large investment project to line irrigation canals to reduce water losses. The total investment plan over the 1999 t o 2005 period was $758 million for all of Vietnam and $52 million for the DNRB. Irrigation and drainage management companies in the basin hope to increase conveyance and distribution efficiency following canal lining from 0.7 to 0.9 (Irrigation and Drainage Management Companies in Ninh Thuan and Cu Chi, personal communication); these

estimates (including the original levels) appear somewhat optimistic. In the baseline, conveyance and distribution efficiency combined are therefore estimated at 0.5.

If the canal lining would increase the conveyance and distribution efficiency across the basin to a level of 0.75, translating into an overall efficiency level of 0.53, then profits from irrigation would increase to 112 percent of OPT levels, an increase of $50 million, at the same time that irrigation withdrawals would decline slightly. Ground water pumping for irrigation purposes would decline dramatically, to 64 percent of OPT levels - a reduction by 95 MCM - as cheaper surface water would become more abundant, while surface withdrawals would increase by 65 MCM. Increased irrigation surface withdrawals, in turn, would lead to a slight reduction in profits from hydropower production ($300,000 annually). Thus, at this level of efficiency increase, the canal lining investment appears to be a viable option compared to costs incurred. If the canal lining activities would increase the combined conveyance and distribution efficiency levels to a value of only 0.6, translating into an overall efficiency level of 0.42, then the additional respective annual profits would be only $22 million. In this case, total irrigation withdrawals would not decline, with a reduction of irrigation pumping of 76 MCM completely offset by a n increase in surface withdrawals (Table 3). Thus, no water savings would be achieved at the basin level.

If, on the other hand, maintenance on primary and secondary canals is deferred - as is happening in many Vietnamese irrigation systems - the combined conveyance and distribution efficiency might decline to a level of 0.38, based on an increase in canal losses of 25 percent and translating into an overall efficiency level of 26 percent. In this case, irrigation profits would drop to 92 percent of OPT levels, a drop of $31 million. The resulting decline in surface irrigation water withdrawals, 18 MCM, would be compensated by an increase in ground water pumping to 107 percent of OPT levels, and total basin profits would decline to 98 percent of OPT values, a decline of $31 million. Thus, even if the canal lining project were not implemented, it is clear that deferring maintenance on public irrigation systems will cause long term costs to the irrigation sector in the DNRB.

Finally, the benefits for irrigation are larger for changes in on-farm field efficiency as they apply to both surface and ground water irrigation sources.



TABLE 3. Irrigation Efficiency and Commodity Price Analysis (comparison with OPT, percentage values).

Total Ag Irrigation Parameter Values Profit Profit Profit Withdrawals Pumping

Level4 Irrigation HP Total

Field Application Efficiencya 0.5 87.5 100.1 96.6 100 69.0 0.9 110.5 99.9 102.8 100 104.6

Conveyance and Distribution Efficiencyb 0.60 105.4 99.9 101.5 100 71.2 0.75 112.4 99.8 103.3 99.5 63.9 0.375 92.2 100.1 97.9 100 106.7

CoffeeFepper Price Changes 1998 130.5 99.9 108.3 100 106.0

2001 82.4 100.8 95.3 97.3 23.8

Note: Runs are based on OPT. aBase efficiency is 0.7. bBase efficiency for combined conveyance and distribution efficiency is 0.5.

Policy Analysis - Water Use Rights, Brokerage Mechanism, and Market Clearing Scenarios

The Vietnam Water Law of 1999 calls for a permit system that applies to both surface and ground water. Use rights for ground water are granted for a period of 15 years and for surface water for 20 years. The permit system only applies to large scale users. Small quantities - chiefly for domestic uses and small scale uses in agriculture, forestry, aquaculture, and other home enterprises - are not included in the permit system. In times of water shortages, domestic uses get priority over irrigation, industrial, hydropower, and environmental uses. In the absence of the implementation of these regulations, allocation is controlled implicitly through investment decisions, where public agencies and companies, through investments in new water-using facilities including irrigation schemes, hydropower stations, ports, and domestic water supply systems, determine de fact0 the basic allocation of surface water among users. Moreover, in the absence of enforced water use rights, the construction of new infrastructure implicitly reallocates water among the various sectors without compensating potential historic users of this water.

Experience in several developed and developing countries has shown that as economies develop and more infrastructure is being built, water is typically reallocated from the agriculture sector to the rapidly growing urban and industrial sectors (Rosegrant and Ringler, 1998). This process can threaten the liveli- hoods of irrigating farmers and associated rural economies. The establishment of water use rights, as envisioned in the Vietnam Water Law and later detailed in government decisions could empower water users in all sectors, as it conveys both rights and responsibilities for water use. If water shifts to

other sectors, irrigators would need to be compensated. However, this requires that representatives of irrigating farmers such as water user associations, farmer cooperatives, or irrigation and drainage management companies are allocated use rights, as farmers are exempted or excluded in the current leg- islation.

The establishment of water use rights together with the possibility to sell unused rights to an agency or to purchase additional use rights if the water can be used productively can help poorer farmers to obtain additional income. Here we will examine the implications of this type of system, which can be implemented in the form of a brokerage mechanism (BRK), on water allocation, use, farmer incomes, and overall basin profits (Pezzey, 1992). In practice, there have been both positive and somewhat less successful experiences regarding the implementation of brokerage mechanisms, also called clearinghouses o r chargehbsidy systems. These systems have so far typically been employed to control air and water pollution. Wang and Chen (1999) present a positive outcome of the application of a chargehbsidy system in China to control industrial pollution. Another case study in France has shown that too much bureaucra- cy can undermine the effectiveness of chargehbsidy systems (Glachant, 1999).

If (water) economies are more advanced, a market clearing (MC) mechanism can be introduced tha t ensures that the volume of water being sold by all users equals the volume being purchased by other users within the same sector or across sectors across specified time periods, here months. The implementation of a market clearing mechanism requires more sophisticated communication and information systems as compared to the introduction of a water brokerage system.


The establishment of water use rights is a highly complex task and requires the determination of many aspects to ensure its workability, including the determination of initial allocation rules. The base water use right scenario implemented here, WRI, envisions a system in which water users are registered in some form with a basin agency or other authority and that the registered use confers both rights t o use the amount registered and the responsibility to use this water in an efficient manner. Alternative water trading scenarios, BRK and MC, envision the purchase and sale of these water use rights to allow water to move into higher valued uses without compromising the incomes of irrigating farmers.

For WRI, water rights are established for all demand sites reflecting historic usage under BAS. For the BRK scenario, in addition to the water use rights, a brokerage mechanism is implemented. All off-stream sectors can sell water up to their water use right allotment t o a brokerage agency or clearinghouse (which could be the river basin agency) that compensates the users at a fixed water price and then can transfer the resource to other sectors that might want to purchase sources in addition t o their own water rights. Sales and purchases are implemented on a monthly basis. Thus, a demand site can buy in the dry season and sell during the wet season, for example. If the water sold to the agency is not allocated to other off-stream sectors, it enhances instream flows. The water price at which the agency buys and sells - the agency water price - is fixed exogenously and is the same for all sectors; under full water market conditions, the water price at which various water users at different locations in the system are willing to sell or buy water can be revealed through the shad- ow price. A third set of scenarios includes a market clearing mechanism (MC) in addition to the brokerage mechanism. That is, water use rights that are sold to or bought from an agency need to be equal in volume. Thus, the agency costs are limited t o transaction costs. Costs for the establishment and management (transaction costs) of a brokerage and market mechanism are difficult to estimate. Here it is assumed that the brokerage incurs transaction costs of $O.Ol/m3 purchasedkold and the market clearing mechanism faces costs of $O.O3/m3. Estimates of transaction costs are set at higher prices compared to those estimated for the western United States, ranging from 6 to 8 percent of prices paid (Colby, 1990; Howitt, 1994), and for Chile, at 7 to 23 percent of transaction prices (Hearne and Easter, 1995). Costs to set up the brokerage and market clearing systems are not included. As the model optimizes over the entire basin, a provision is included for the BRK and MC scenarios tha t individual demand sites cannot be worse off than under the WRI case. The alternative scenarios are

implemented based on the OPT scenario, that is, they include variation in area, yield, and crop inputs and use the BAS initial water use right allocation.

Table 4 presents selected results for the water use right scenarios with the alternatives of BRK and brokerage with market clearing under two alternative transaction prices ($O.O2/m3 and $0.06/m3). When BRK is introduced, water withdrawals change significantly compared to the fixed rights system, with the outcome depending directly on the agency fixed sale/purchase price. In the case of a transfer price of $O.O2/m3, all sectors are net buyers, and a total of 1,690 MCM are traded under BRK, providing the agency a net income of $34 million from water sales for the river basin as a whole. At the same time, gross irrigation withdrawals increase to 8.7 km3. All sectors with established water use rights gain from the clearinghouse mechanism. However, the benefits t o instream uses like hydropower and environmental uses decline, as they do not have water use rights accorded based on the water law and reflected in the river basin model. Moreover, although total profits in the irrigation sector increase, these profits are spread over a much wider irrigation area, and more low- value, water intensive crops are brought into production. As a result, profits decline on a per hectare basis compared to the system with fixed water rights from $59l/ha to $538ka.

If the water price in the BRK system is set at a higher level, here $O.O6/m3, it is more profitable for many irrigation systems to sell part of their water use right to the water agency than to continue using the full share of allocated use rights. All in all, the water agency purchases 1.2 km3 worth of water at a net cost of $74.6 million. This is because the volume of water sold by farmers at this higher water price is far larger than the volume of additional water demanded by the domestic and industrial sectors (Table 4 and Figure 5) . Due to the large sales of water out of irrigated agriculture, the volume of gross agricultural water withdrawals declines to 3.1 km3 and irrigated area drops to 0.497 million hectares. As a result, profits from irrigated agriculture alone under the higher water price of $0.06/m3 are lower compared to the irrigation profits at the agency-set price of $O.O2/m3. However, the important result is that under the higher water price, profit from irrigated agriculture on a per hectare basis is significantly higher ($779/ha) compared to the WRI scenario ($59l/ha) and the BRK scenario at the lower agency set price ($538/ha). At the price offered for the water use right, irrigating farmers make a substantial share of their use rights available t o other off-stream users or the environment, while investing their remaining water resources into crops that are more profitable per cubic meter of water (“crop per drop”). Thus, water moves to

RINGLER, Vu HUY, AND MSANGI



TABLE 4. Selected Results From Water Trading Analysis, WRI, BRK and MC Scenarios.

WRI BRK 0.02 BRK 0.06 MC 0.02 MC 0.06

Agency Fixed Trading Price ($/m3)

Irrigation Profit (M$) Domestic Benefit (M$)

Industrial Benefit (M$)

Hydropower Profit (M$)

Total Profit (M$) Total Water Withdrawals (MCM)

Irrigation Withdrawals (MCM)

Irrigated Area (in '000 ha)

Agency Incomei(cost) (M$)

Farmer Sells (buys) (M$) Domestic Sector Sells (buys) (M$)

Industry Sells (buys) (M$)

Quantity of Water Traded (MCM)

Average Farm Income Per ha ($/ha)

Average Irrigation Water Per ha (maha)

401

687

155

155

1,397

6,309

5,615

678

0.02

486

1,057

162

153

1,858

9,670

8,719

904

0.06

387

1,057

160

154

1,757

3,923

3,054

497

~~

0.02

435

1,057

161

154

1,806

6,326

5,411

685

0.06

434

1,057

16 1

154

1,805

6,334

5,430

693

591

8,279

33.8

-27.4

-4.3

-2.1

1,690

538

9,646

-74.6

89.1

-12.4

-2.1

1,485

779

6,147

n.a

5.7

-4.2

-1.5

284

635

7,898

n.a.

16.5

-12.6

-3.9

275

627

7,836

m In selU(buy) rn Dom selU(buy)

100 1

Ind selU(buy) PA Gov Incl(costlenv)

80 60 40 20 0

-20 -40 -60 -80 1

-100 J

Figure 5. Water Use Right Scenarios: Water SaleslPurchases and Agency Income/Cost (Environment).

higher valued uses without income losses to the irrigation sector.

If in addition to the brokerage mechanism a market clearing mechanism is introduced, that is, net sales need to equal net purchases of water use rights, the volume of purchases and sales drops compared to the BRK scenarios. At the water price of $O.O2/m3, irrigation demand sites are unable to purchase water as domestic and industrial sectors themselves strive

to purchase water from lower value irrigation. At the higher water price, trade is even more limited, as domestic and industrial sectors purchase less water than the irrigation sector might be willing to free up at this price. While the quantity of water traded was 1,690 MCM under BRK $0.02 (that is, at the agency set price of $O.O2/m3) and 1,485 MCM under BRK ($0.06), the corresponding volumes under the market clearing mechanism drop to 284 MCM under MC



1,200 -

1,OOO

800 n u) 3 800

$0.02 and 275 MCM under MC $0.06, respectively. Although net farm income per hectare under MC does not reach BRK levels - at which the agency supports water sales from irrigated areas even if no one purchases this water - net profits per hectare irrigated are still greater than under the WRI case.

Figure 6 presents the income of farmers from irrigation activities and from the sale of water use rights, as well as overall profits of the nonirrigation sectors, under the alternative water use rights and trading scenarios. At the lower water price, $O.O2/m3, irrigation demand sites are net purchasers of water under the BRK scenario, spending a total of $27.4 million on additional water use rights, 5.6 percent of total irrigation profits, 20 percent of total surface irrigation withdrawals, and 19 percent of total irrigation withdrawals. Under the higher water price, irrigating farmers are net sellers of water, obtaining 23 percent of total profits from water sales and selling 33 percent of total irrigation withdrawals, or 3 percent of total basin discharge. Under the MC scenario, in which irrigation sites are net sellers at both specified water prices, incomes from water sales are $5.7 million (1.3 percent of total irrigation profits) and $16.5 million (3.8 percent of total irrigation profits) under the water transfer prices of $O.O2/m3 and $O.O6/m3, respectively. Under market clearing conditions, water sales out of agriculture reach 5 percent of total surface withdrawals under both alternative agency-set water prices. Nonirrigation water users are better off under both sets of BRK and MC scenarios, as they can purchase additional water use rights (Figure 6).

-Water trade: Inc I Cost Irrigation Pmflt (M USD)

+Other profitdbenefits

s 400

200

0 WRI -0.02 BRKO.06 MCO.02 MC0.06 -200 1

Figure 6. Water Use Right Scenarios: Total Irrigation and Other Profits.

As the Dong Nai basin economy develops and water becomes scarcer, the agency price could be increased to reflect the increasing value of water in the basin, thus prompting additional water sales and investments in water saving technologies in irrigated agriculture as well as in the purchasing water use sectors.

Commodity Price Changes

With increased opening to international markets, Vietnam’s farmers are experiencing larger fluctuations in agricultural commodity prices. In particular, commodity prices for coffee and pepper have varied considerably over the past several years, with adverse impacts on farmer incomes. To evaluate the impact of these price changes, alternative simulations are car- ried out for the 1998 and 2001 coffee and pepper prices, and results are compared to the 1999-2000 values obtained through the household survey. Convert- ed to US . dollars, the prices used for coffee are $1,033/t7 $64llt, and $372/t, for 1998, for the survey year (1999-2000), and for 2001, respectively. This rep- resents a drop by a factor of 2.7 over three years. For pepper, prices were $4,59O/t, $3,392/t7 and $1,149/t for the same three years, reflecting a drop by a factor of four over the period. The results of the alternative simulations are shown in Table 3. If the 1998 coffee and pepper prices would prevail, irrigation profits would increase to 131 percent over OPT values and total basin profits to 108 percent. For the case of 2001 coffee and pepper prices, profits from irrigated agriculture drop to 82 percent of OPT values, and total profits decline to 95 percent of OPT values. In the lat- ter case, total irrigation withdrawals decline slightly. Moreover, ground water pumping, which is a major water source for pepper and coffee crops, drops sharply, t o 24 percent of OPT levels, while profits from hydropower production slightly increase. The reduction in pepper and coffee prices lead to a large reduction in gross water withdrawals, from 6.6 km3 to 5.6 km3, and a decline in gross irrigated area by 50 million ha, reflecting the large impact of commodity prices on farmer decisions and incomes.

Open Economy, International Linkages - TRDLIB

During the past decade or so, Vietnam has become a major or even the largest player in some international agricultural commodity markets, including pepper, coffee, and rice. Plans t o join the World Trade Organization (WTO) by the end of 2006, increased participation in international agricultural commodity markets, and increased openness to trade in general have led to the removal of most distortionary export taxes and import quotas that have been in place in the past but also have led to increased exposure of farmers to fluctuations in international market prices, as shown above.

The Open Economy and International Linkages Scenario, TRDLIB, simulates the impact of changes in national level support policies on basin level water



use. It assumes a continuation of market liberalization trends culminating in the full removal of primary economic distortions (taxes, subsidies) that affect agricultural production (and hence agricultural water use). The Dong Nai basin economy, centered on irrigated crop production, is linked to global conditions via internationally established prices of inputs (fertilizers and energy, for example) and outputs (agricultural commodities). Farmers face producer prices set in international markets and mediated by costs of inland transportation, storage and marketing margins. The scenario does not take into account secondary effects of increased trade liberalization, like a reduction in marketing margins, which will likely occur as the powers accorded to few traders are grad- ually relaxed during the increased opening to international markets. Moreover, industrial protection levels for raw materials that also affect farmer decisions (for example in the sugarcane industry) are not examined under this scenario.

As a study by Barker et al. (2004) shows, overall subsidy and taxation levels in the agriculture sector have declined substantially in Vietnam over the past two decades. In 1999-2000, estimated average net protection rates were -7 percent for rice (i.e., farmers are net taxed), -7.5 percent for coffee, -13 percent for pepper, +7.5 percent for tobacco, +112 percent for sugarcane (1998-1999 average, industrial protection), and +16.5 percent for urea. Sugarcane and urea protection is intended to support local industries and in doing so harms farmers. The case of urea is particularly significant, as it affects most crop production. Distortions are lower for other fertilizers, such as potash and potassium, because they are mostly imported. If remaining trade barriers were removed, domestic prices received by farmers would increase for rice, coffee, and pepper and decline for tobacco. Urea fertilizer costs to farmers would decline significantly (Barker et al., 2004).

The objective of TRDLIB is to analyze the impact of the removal of the net taxation/protection level - assumed to occur by 2010 - on cropping patterns, water allocation, and farm incomes. In order to implement the trade liberalization scenario, the protec- tionftaxation levels were removed for the irrigated crops in the basin model; that is, rice prices were increased by 7 percent, coffee prices by 7.5 percent, and pepper prices by 13 percent, and tobacco prices were reduced by 7.5 percent and urea prices by 16.5 percent. This scenario was compared with a business- as-usual (BAU) scenario for 2010.

Results for TRDLIB indicate that direct annual farm income would increase by $89 million. Figure 7 shows the changes in profitability per hectare for the three major crop types. Profit per hectare increases most for rice crops, by 22 percent (from $182/ha to

$223/ha>, followed by perennial crops by 13 percent (from $1,465/ha to $1,658ka), and upland crops by 0.4 percent (from $1,048/ha to $1,053/ha). The large increase in profitability of rice crops is due to the com- bination of larger received output prices and reduced fertilizer input costs. The same applies for some of the perennial crops like coffee and pepper. These crops also use relatively greater amounts of urea fertilizer. Nitrogen equivalent fertilizer, for example, averages 343 kg per hectare and year for perennial crops as compared to 119 kg/ha for paddy and 125 kg/ha for upland crops, based on computations from the survey data. However, urea plays an important role in all crop types, and the removal of urea protection is equivalent to a direct net transfer of income to irrigating farmers.

29000 1 1,658

Perennial Upland Rice

Figure 7. Profit Per Hectare by Crop Type, TRDLIB and BAU Scenarios.

Total irrigated a rea increases slightly under TRDLIB compared to BAU, as the TRDLIB scenario helps move some of the unprofitable rice area back into the positive profit margin area. Moreover, under TRDLIB, N-fertilizer application increases from an average of 168 kg/ha for irrigated crops in the basin under BAU to 179 kgka, and the (complementary) P-fertilizer application increases from 126 kgka to 129 kg/ha, while K-fertilizers barely change.

CONCLUSIONS

In this study we introduced an economic hydrologic river basin model and its application to the Dong Nai River Basin in southern Vietnam. The model describes the water supply situation along the river system and the water demands by the various water- using sectors. Water benefit functions are developed for productive water uses, and minimum instream



flows are included as constraints. Water supply and demand are then balanced based on the economic objective of maximizing net benefits from water use. This structure allows for intersectoral and multi- province analyses of water allocation and use with the objective of determining tradeoffs and complementari- ties in water usage and strategies for the efficient allocation of water resources.

This type of model can help the provinces in the newly formed Dong Nai Planning Management Coun- cil to structure the complex reality of the Dong Nai water resources system. The model can be used as a planning tool, focusing on the investment side, and even more so as a tool to develop strategies for basin management. The model can support policy makers in their decision making processes from an economic efficiency perspective. Water allocation mechanisms need to be efficient, equitable, and environmentally sustainable. The model developed for the DNRB inherently ensures efficient water allocation in the basin as water is allocated according to its scarcity value to the highest valued uses and, once those are satisfied, to other uses, so long as the overall economic profit from water use across the basin increases. Finally, the model allows analysis of the impact of policies on outcomes for water and farm incomes at various levels, from changes in farmer behavior and decisions at the localhop area level, to basin level changes in water allocation mechanisms, up t o national level changes in macroeconomic input and output price policies.

Alternative scenarios changing the overall irrigation efficiency in the basin have shown that water savings could be large. However, the appropriate means t o achieve these savings - either through structuralhnfrastructure measures, as chosen by the government, or through nonstructural measures such as improvement in management or the implementation of a brokerage mechanism - warrant further analysis and discussion. Based on the model simulation, only high levels of actual efficiency increase - for example, an increase in the combined conveyance and distribution efficiency to 0.75 - would actually lead to sufficient increased annual benefits through water savings to make infrastructure investments viable. However, other benefits, including cost savings due to reduced operation and maintenance (O&M) from canal lining also would need to be considered. On the other hand, cessation of joint farmer canal cleaning can be a stumbling block for irrigation management transfer and farmer management of irrigation systems and thus might not be conducive to the ongoing, albeit slow, process of decentralization in Vietnam's irrigation sector.

Results from the water use rights scenarios have shown that appropriate incentives can shiR irrigated

area allocation toward water savings while farmer incomes are maintained and urban and industrial water use shares increase. Although not shown explic- itly on the basis of alternative scenarios, the establishment of water use rights alone does provide security for all types of water users, as they guarantee a long term right to access to a specific volume of water, which can lead to investments for improved water use in all sectors and supports longer term cropping decisions toward more high value (and riski- er) cropping patterns. In particular, by making the limits to water use explicit, water use rights create incentives for the implementation of water saving technologies to meet future demand. The results from the alternative clearinghouse mechanism (BRK and MC) scenarios have shown that farmers and other water users do respond positively to changes in the incentive structure for water allocation and use. For example, water sales from irrigated areas occur more often when rice constitutes a large share of the irrigated area in the specific demand site due to the lower value of water in rice irrigation compared to other cropping systems.

In the case of the brokerage system, special atten- tion has to be paid to setting the agency fixed water price at which users can sell part of their water use right or obtain access to additional water. At relatively higher water purchase and sales prices - for example, at the $O.O6/m3 used here - irrigators tend to sell part of their water use rights at the same time that profits from irrigated agriculture on a per hectare basis increase significantly, as water in low value uses is sold first; here average profits per ha increased to $779/ha, and farmers earned an additional $89 million from water sales, but total profits from irrigated farming alone in the basin declined to $387 million. The water sold by irrigation sites translates into real water savings at the basin level that can enhance instream flows or can be used to meet urban industrial demands. If, on the other hand, the water pur- chasehales price is relatively low - for example, at the $O.O2/m3 used here - then irrigation sites will tend to purchase additional water, here for $27 million, resulting in lower average profits per ha, here $538/ha, while total irrigation profits are higher, here valued at $486 million. In this case, instream flows decline, but irrigated area and farm employment increase. Thus, the brokerage systems can help achieve water savings in irrigated agriculture without hurting the net income situation in rural areas; in fact, farmers' incomes are enhanced if appropriate incentives are provided.

We have examined the brokerage mechanism here, as it is relatively easier to implement in a developing country context, once water use rights are established, because it requires no market clearing



mechanism. However, as the results also have shown, depending on the clearinghouse set water price (and on the water scarcity or abundance situation), large volumes of additional water might be purchased, resulting in net incomes to the agency but net losses to the environment and possibly to hydropower production, or large volumes of water use rights are sold to the agency, in which case the environment and hydropower benefit a t a net monetary cost to the agency. The introduction of a market clearing mechanism avoids these possibly extreme - albeit within physical, technical, system, and economic boundaries - sale and purchasing events by placing a limit on water use right sales, as bids to sell water are balanced with existing demands for additional water. However, the implementation of an MC scenario in practice requires a complex information and management system, with large ensuing transaction costs that would need to be estimated in detail prior to establishing such a system.

The analyses also have shown that irrigation sites will only sell part of their water use rights; that is, the introduction of water trading does not necessarily lead to the cession of agricultural activities. According to the model simulations, if water can be sold to or purchased from a clearinghouse, irrigators spend 5.6 percent of their farm incomes on purchasing additional water (to obtain 20 percent of their surface withdrawals) at the lower agency water price. At the higher price, irrigators obtain 23 percent of their total irrigation profits from water sales and sell 33 percent of withdrawals, or 3 percent of total basin discharge. If market clearing is introduced, 1.3 percent and 3.8 percent of the average farm income is obtained from water sales at the lower and higher water trading price, respectively, and 5 percent of irrigation water is transferred out of agriculture.

Finally, the application of both water trading instruments is very flexible and can adapt t o the changing scarcity value of water in the basin. When water is abundant, a low water price for sales and purchases can be set, and most water will be used within its respective intended use. As the basin economy develops and water becomes scarcer, the agency price could be increased to reflect the higher value of water in the basin, thus prompting additional water sales and investments in water saving technologies in irrigated agriculture and other water use sectors.

The simulation of a l ternat ive output prices received for pepper and coffee has demonstrated their large impact on the total basin economy over recent years. The drop in coffee and pepper prices is particularly worrisome, as these perennial crops are long term investment decisions that cannot be changed in the matter of a season or even a year. The multiyear reduction in coffee prices in Vietnam, in fact, has led

to the destruction of several thousand hectares of coffee plants, mostly older and less productive ones, and has led to the substitution of some area planted to the robusta variety with the more highly priced arabica variety. However, coffee prices have since recovered to closer to 1998 levels, returning the crop back to profitability. The decline in pepper prices was not large enough to wipe out pepper production areas. Stabiliz- ing and increasing farm gate prices through improved quality and other measures must be a key goal for Vietnam’s agricultural policy, particularly for perennial crops, which cannot quickly adjust to the large price swings experienced in the basin in recent years. Moreover, a scenario analyzing the impact of remov- ing primary economic distortions (taxes, subsidies) that affect irrigated agricultural production (and hence agricultural water use), compared to the current situation, has shown that the prevailing pattern of price distortions has significant impacts on water usage at the basin and national levels. The removal of remaining agricultural protection and subsidies would lead to direct annual farm income increases of $89 million in the Dong Nai River Basin for the future 2010 estimate. Thus, distorted input and output price policies also distort incentives for efficient land and water allocation in irrigation and other water using sectors. Efficient allocation of land and water resources at the basin level would be enhanced if policy makers removed remaining distortions at the macro level in Vietnam and elsewhere.

ACKNOWLEDGMENTS

This paper is a product of the ADB RETA project No. 5866, “Irri- gation Investment, Fiscal Policy, and Water Resource Allocation in Indonesia and Vietnam.” It combines work by the International Food Policy Research (IFPRI) Institute, Washington, D.C.; the Sub- Institute for Water Resources Planning (SIWRP), HCMC; and the Sub-National Institute for Agricultural Planning and Projections (Sub-NIAPP), HCMC, Vietnam. Helpful comments have been received by Consuelo Varela Ortega and three anonymous review- ers.

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WATER ALLOCATION POLICY MODELING FOR THE DONG NAI RIVER BASIN: AN INTEGRATED PERSPECTIVE1