PPrraaddhhaann MMaannttrrii KKrriisshhii SSiinncchhaayyeeee YYoojjaannaa ((PPMMKKSSYY))

District Irrigation plan of

Nicobar Islands

2016

Andaman and Nicobar Administration

Andaman and Nicobar Islands

Port Blair-744 101

Contents

Sl.No Particulars Page No.

i Vision and Strategy

ii Data sheet about irrigation plan for A&N Islands

1 The Background

2 Rainfall and topography

3 Soil resources and irrigation frequency

4 Water requirement

5 Present status

6 Irrigation policy for A&N Islands

7 Planning of new scheme

8 Water resource development strategy

9 Physical and financial estimate

10 Design and size of different water storage / irrigation units

Vision

Access to Irrigation to every farm (Har Khet ko Pani)

Strategy

• Increase gross irrigated area

• Bridging the gap between irrigation potential & utilisation

• Enhance water use efficiency & Management

• Creating/Strengthening Water distribution network

Data sheet of irrigation plan for Nicobar district

Name of the state / U.T Andaman and Nicobar Islands

District Nicobar Islands

Nodal department Directorate of Agriculture, A&N Administration, Port Blair

Net agricultural area 17676 ha

Gross cropped area 17676 ha

Area sown more than once -

Major source of irrigation / water Surface stream and shallow ground water

Total annual rainfall 2800 mm

Irrigated area -

Existing schemes Plan scheme- Development of Minor Irrigation in ANI

Proposed area coverage ha

Brief method Check dam cum well, ring wells, farm pond, rainwater

harvesting, lined ponds, drip etc.

Duration 2016-2020 (4 years)

Financial outlay (lakhs) 225.00

Expected benefit

Cropping intensity (%)

Major crops to be covered

Crop Productivity

150-200

Vegetables, Coconut, Arecanut, Spices, Banana

50 -120 % increase of base yield

Method of implementation As per the guidelines of (PMKSY)

Collaborators Directorate of Agriculture, ICAR-CIARI, Dept. of Envt. and

Forest, APWD, Rural Development & PRI’s

Prepared by:

ICAR-Central Island Agricultural Research Institute

Directorate of Agriculture, Haddo, A&N Administration

Approved by: State Level Sanctioning Committee (SLSC) / Project Screening

Committee headed by Chief Secretary

1. The Background

The Andaman and Nicobar (A&N) archipelago comprises of about 556 small and big

Islands covering an area of 8,249 sq km with a coastline of 1,962 km between 92-94° E

longitude and 6-14° N latitude in the Bay of Bengal. The northern group of Islands forms

the Andaman Islands, while the southern group of Islands forms the Nicobar Islands, which

is separated by 10° channel.

Agriculture is the mainstay of the economy of A&N Islands which provides livelihood for

about two third of the population. However, it depends largely on monsoon rains from June

to December, and rest of the period is called dry season during which evapo-transpiration

is very high and rainfall is low.

The Nicobar Islands receive an average annual rainfall of about 2800 mm. About 95

percent of annual rainfall is received during May-December of which nearly 75 percent is

lost as runoff to the sea due to undulated terrains and steep slopes. The Islands have a

width of 5 to 40 km east to west and the slopes are from centre to either towards east or

west due to which the length of drainage line to the sea is short. Because of this, only

Galatea river in Great Nicobar is perennial. But, it drains and located deep inside reserved

forest.

The actual water availability is much less and Islands faces severe problem of water

scarcity even for drinking water during the summer season. The population of these

islands has also significantly increased and in order to support the food requirement of the

Islanders, emphasis should be given to produce adequate perishable items such as fruits

and vegetable. This will provide decent livelihood to the island farmers rather than

transporting from mainland.

In spite of good amount of total annual rainfall received on these islands the created

irrigation potential is less than 3%. As rainwater is the only source of the fresh water

availability in these Islands, its harvesting, storage and recycling is the most important

strategy for water resource management. Studies carried out at Central Island Agricultural

Research Institute, Port Blair indicated that if only 3-5% of the water which flows out is

stored in surface and underground storage, the requirement of domestic and agriculture

can be met. A detailed irrigation development plan involving all the stakeholders is very

essential as the island is also facing the imminent threat from climate change associated

events.

2. Rainfall and topography

These Islands fall under agro-climatic zone XV and have a true maritime climate

with least variation in maximum and minimum temperatures throughout the year. The

Islands receive an average annual rainfall of about 2800 mm. A surplus of about 1530 mm

rainwater from mid-May to mid-December and a deficit of about 610 mm are experienced

during January-April, when number of rainy days in each month hardly exceeds three.

Fig. 8. Climatic parameters of Nicobar Islands

The topography of the Islands is rolling with low range hills to narrow valleys at the

foothills resulting in an undulating terrain ranging from steep slopes (>45°) to coastal plains

(<10°). Physiographically, the land in these Islands can be subdivided into: (i) moderate to

steep hill ranges (ii) intermountain narrow valley and (iii) coastal tracts including swamps.

The huge hill ranges are generally covered by dense forest. Nearly 75 percent of

the rainfall received in the Islands is lost due to undulated terrains, steep slopes, porous

soil stratum and its proximity to the sea. Therefore, water conservation methods should be

given importance while planning irrigation development, particularly for undulated and hilly

terrains. As rainwater is the only source of the fresh water availability, its harvesting,

storage and recycling forms the most important strategy for natural resource management

in these Islands.

3. Soil resources and irrigation frequency

Soil type greatly affects the irrigation frequency and water storage after irrigation.

Coarse textured soils require frequent and more irrigation to support the crop, whereas,

fine textured soils with high organic matter content need comparatively less water. The

soil type of Nicobar Islands ranges from loam to sandy loam. These have developed under

the dominant influence of vegetation and climate over diverse parent materials such as

fragmented granites, marine sediments, and outwash materials in the valley floors. The

uplands are intensely leached, runoff is very high, and have shallow soil depth.

Sometimes very shallow and gravelly, this is not suitable for intensive irrigation

developments. Moderate to deep soils with alluvial or clay loam are highly suitable for

intensive agriculture with irrigation facilities. The valley floors comprise of depositional

landforms and have developed from the out wash of parent material from the surrounding

hills. These soils are medium to heavy textured, moderately well drained, and subjected to

seasonal fluctuations in ground water.

Soil / site not suitable for irrigation

These soils should be irrigated frequently particularly during dry season as most of the

soils are coarse textured. This also necessitates use of mulching and improving the water

holding capacity of soils.

4. Water requirement

It is very important to estimate the future water demands for different Islands while

making irrigation development plan taking in to account its projected population and food

requirements. The average crop water requirement to produce different commodity in

Nicobar Islands is given in table.

Crop water requirement

Commodity Crop water

requirement (m3/t)

Cereals 4254

Pulses 1000

Tubers 1000

Vegetables 1000

Fruits 1000

Coconut 1780

Arecanut 2222

Oils 1500

Milk 1369

Meat 5180

The amount of water involved in agriculture is significant and most of it is provided

directly by rainfall particularly to produce rice crop during monsoon season. An estimation

of Island water needs for food production can be based on the specific water requirements

to produce food per capita. The present average food ingest 2800 kcal/person/day may

require 1000 m3 per annum to be produced. Most of it is provided by rainfall stored in the

soil profile and only 1.5% is provided through ponds created under minor irrigation.

Although, on an average about 25% of water can be withdrawn from rivers, lakes and

aquifers for agriculture to effectively contribute for crop production (the rest is lost through

overland flow, evaporation and deep infiltration) but considering the typical topographic

conditions, high intensity rainfall and narrow breadth of the land mass in Nicobar Islands,

only 15-20% of the water resources can be potentially developed. The water demands for

selected critical Islands are given in Table. It indicated that development of 3.4 - 5-4% of

the available water resources in different islands could meet their requirements.

Projected water demand in selected islands

Name of the

Island

Area

(km2)

Projected water

availability (m3/capita)

Projected

water demand

BCM

Water resource

development (% of

water availability) 2021 2051

Car Nicobar 126.9 12349 6043 0.034 6.5

Chowra 8.2 11691 5722 0.003 6.0

Teressa 101.4 98833 48357 0.001 4.5

Katchal 174.4 64832 31726 0.001 5.2

Kamorta 188.2 108922 53296 0.002 5.4

Great Nicobar 1045.1 272769 133478 0.001 5.1

5. Present status

There is no irrigation facility in Nicobar Islands and the entire district under rainfed

due to various reasons. Therefore, a pragmatic approach and policies for water resource

development for irrigation in these Islands is required to be adopted. Bore wells are not

feasible in marine sedimentary formations whereas dug wells of 4-5 m diameter to 6 m

depth may yield good water. The igneous rocks do not form potential aquifers but form

aquifer both in weathered mantle and fractured basement rocks which are generally

developed through dug well, ponds and bore wells. A small check dam across streams

may also constitute potential source of irrigation particularly during dry season in the

district.

Under various centrally sponsored schemes and plan project very few minor

irrigation structures were constructured in these islands. In addition, other organizations

and NGO have also created some irrigation facilities in the islands. However, when

compared to Andaman Islands it appears to be very little. Many of these structures are not

in use due to improper maintenance, sedimentation, destroyed by flooding or some other

problems. The irrigation benefits from this M.I are minimal which are constrained by

topography in addition to the problems cited. Therefore, the potential one can be

renovated and addition area can be brought under irrigation. Due to the terrain and

isolation of islands the irrigation facilities are not adequately developed. Each island or

district has its own problem and potential, hence, island specific approach will be required

to improve and use the irrigation facilities.

6. Irrigation policy

Unlike other parts of the country, Union Territory of A&N Islands is a non-contiguous group

of Islands. Therefore, each Island should be treated as single entity for water resource

planning and development. The important Islands should have a comprehensive land and

water resource management plan, keeping in view the environmental and ecological

impacts. The general water policies for A&N Islands are given below:

Integrated and coordinated development of surface water and ground water

resources and their conjunctive use should be envisaged right from the project

planning stage and should form an integral part of the project implementation.

Irrigation planning should be based on demand rather than supply. Irrigation

intensity should aim to extend the benefits of irrigation to more farm families to

maximize the production.

Conjunctive use of surface and ground water through rainwater harvesting in farm

ponds and wells located on seepage line should be promoted. In porous soil areas,

lining of pond with silpaulin / geo-membrane with covering material to protect from

high daily insolation should be encouraged through subsidy.

Efficient irrigation techniques such as drip irrigation for plantation/spices/fruit crops

(coconut, arecanut, black pepper, clove, banana, watermelon etc.) and sprinkler for

vegetables should be promoted.

Water conservation measures such as, mulching, residue soil moisture

management, minimising evaporation losses, promotion of low water requiring

crops should be considered.

Both surface and ground water should be monitored regularly for its quality.

Management of the water resources for diverse uses should incorporate a

participatory approach. As rainwater harvesting is linked with the watershed

programs, involving water user associations (WUA) at village level will help ensure

productivity and equity aspects. WUA and the local bodies such as panchayats

should particularly be involved in the operation, maintenance and management of

water infrastructures / facilities.

7. Planning of new scheme

Only minor irrigation projects, community water resource assets at village level and

individual water harvesting units at farm level supported with water conveyance system

along with efficient cropping pattern will be an ideal option for developing irrigation system

to provide water to every farm household. The details are discussed below:

7.1 Participatory approach

It should be emphasized here that the participation of future beneficiary farmers is a

very important factor in designing and constructing new irrigation networks. If farmers are

encouraged to collaborate from the beginning, then operation and management of the

scheme can well be organized, and farmers will hopefully feel an element of personal pride

in the scheme. Further, the involvement and input from the public representative, PRI

members will be encouraged. Therefore, exact location of the individual units like ring

well, check dam etc will be finalized in later stage of implementation.

7.2 Crop planning and intensification

In order to harness the maximum benefit from the proposed irrigation plan, two

major modification of the existing cropping pattern needs to be done. The most important

aspect of the proposed plan at individual farm house hold is that it has to meet the crop

water requirement under island agro-climatic conditions. Secondly, the existing cropping

pattern has to be suitably modified / intensified to get maximum benefit by providing

irrigation. This means intensification and diversification of agriculture based on the

existing cropping pattern in any farm household.

For example, the existing coconut and arecanut plantations should be diversified by

introducing multistoried cropping. While doing so, efforts will be made to produce them

under organic cultivation. Therefore, organic cultivation of spices will get the boost.

Similarly while introducing drip irrigation facilities to wide spaced fruit crops like banana

and papaya, intercropping with seasonal vegetables will be promoted thereby, increasing

the water productivity.

Proposed crop alignment and expected cropping intensity

Sl.No Existing major cropping pattern

Proposed modifications Irrigation method Expected cropping

intensity (%)

1 Coconut Coconut + Black pepper+ tree spices + pine apple or fodder Coconut + black pepper + vegetables

Tank-well with drip/ electric motors Dug well with drip Lined pond with gravity fed drip

150

150

2 Arecanut Arecanut + Black pepper+ tree spices + pine apple or fodder

Tank-well with drip Dug well with drip / electric motors

150

3 Banana / papaya and others

Fruits + vegetables Sugarcane + vegetables

Dug well with drip Lined pond with gravity fed drip

150

4 Vegetables Vegetables-High value crops Protected cultivation of high value vegetables

Tank-well with water pipes /drip Dug well with water pipes /drip

200

5 Waste land / backyards / rice

Vegetable-vegetable Protected cultivation of high value vegetables / floriculture unit / peri-urban horticulture

Land shaping for BBF, P-F, FP Dug well with drip / rainwater harvesting /electric motors

200

6 Backyard Fruits and vegetables in the backyard / community garden in tribal areas

Dug well with drip / rainwater harvesting / electric motors

150

8. Water resource development strategy

The water resource development plan in A&N Islands should be based on utilization

of rainwater either through surface storage or enhanced groundwater recharge within

each island. Considering the topographical constraints, surface storages at different

inhabitation area/cultivated land instead of centralized location should be preferred. The

drainage network of A&N Islands should be used for developing the water resource plan.

8.1 Surface water

For surface water development on a drainage line, a three tier water resource

development plan should be developed. This will include,

i. Development of plastic film lined tanks on the top of the hills

ii. Recharge structure cum well system in the mid-hills and

iii. Development of open dug wells in the valley areas.

The recharge structure cum well system in mid hills can be both dugout or

impounded type or combination of both depending up on the topography of a location.

i. Hill top :

In order to develop water resources at hill tops, lined tanks can be constructed. For

one hectare of arecanut, a tank of about 1500 m3 will suffice. This size need not be created

at one site but can be distributed in the whole area. For wide spaced crops like coconut

and cashew, the tank size requirement will be further less.

Process of lining of tank (a) dug out tank (c) reinforced plastering

ii. Mid Hills

In mid-hill areas, recharge structure cum well system can be adopted for water

resource development. A series of recharge structures in the form of small pond or check

dam can be constructed in the stream itself at appropriate sites where storage of about

1000 to 5000 m3 can be created. These storages, besides storing water will also recharge

shallow aquifer. Open dug wells of 4-5 m diameter in the downstream of the recharge

structure can recover back the recharged water. The surface storages can be used for

providing water for initial period of dry season whereas water from dug well can meet the

water requirement in rest of the season.

iii. Coastal areas

In these areas waterlogging and sometimes sea water intrusion is a problem.

Therefore, the strategy should address both of these two. Different land shaping methods

such as raised bed and furrow system, ponds with broader dikes, Rish-fish system etc. are

proved to be highly successful in these region. This could help in in-situ harvesting of rain

Check dam Well downstream of check dam

water, diversification of agriculture and bringing new areas under irrigation particularly

during the dry season.

Raised bed and furrow system Farm pond

In addition, rainwater harvesting and storage in a small lined pond or plastic tanks will also

provide life saving irrigation to crops grown in the homestead garden, which is the

predominant form of vegetable cultivation in the Car Nicobar Island.

8.2 Locating the irrigation sources

Nicobar group of islands (a) Car Nicobar (b) Kamorta and Nan cowry (c) Campbell Bay)

Small streams in Car Nicobar can be targeted for making check dam

8.3 Efficient use of water

i. Irrigation methods

Application of water to the field / plant root through lined or unlined canals, distributaries

and through any suitable outlet is called irrigation. There are different methods of

irrigation, but for Island condition the following methods are suggested;

Basin : It is useful mainly for plantation trees, only the basin around the tree is

irrigated

Ridges and furrow : This is applicable for row sown crops particularly vegetables.

After earthing up, it protects the crop from lodging and it can drain excess water to

certain extent.

Check basin : The field is divided into small plots surrounded by small bunds on all

the four sides. Water from head channel is supplied to the filed channels one after

the other.

Drip irrigation : Here water is allowed to drip slowly to the roots of plants, either

onto the soil surface or directly onto the root zone, through a network of valves,

pipes, tubing, and emitters. It is done through narrow tubes that deliver water

directly to the base of the plant.

Pitcher irrigation : This is use of perforated pots, placed near the base of the trees.

ii. Extension of irrigation scheme

When an area generally suitable for irrigation is identified, the exact area that would

receive irrigation water should be determined. Any area which is considered for an

extension or for a new scheme should not have steep slopes but be rather flat, with a

gentle slope downwards from the existing scheme or from the water source. See Figure

46, which shows the profile of the land area along the line from the water source to

possible new irrigation areas. Such a land profile map can be used to judge whether

extension of an old scheme or construction of a new irrigation scheme is feasible with

regard to water delivery.

When it is not certain whether the new area can be irrigated without difficult

problems, a detailed topographical survey of the area should be carriedout.

iii. Water conservation

In areas where slope is more than 2%, mostly coconut, arecanut and vegetables are

grown. In majority of the areas bunds are made only to indicate the farm holding,

sometimes no bund is made. In those areas, raising of field bund across the contour,

terracing in sloppy coconut gardens, ring / check basin will conserve both soil and water.

In situ water conservation measures and minimization of high evaporation should be

promoted to improve the crop productivity in addition to extension of existing irrigation

facilities. Some of the methods are,

Organic mulching / Stubble / husk mulching

Cover crops

Mulching

Staggered catch pit:

Half moon shaped bund with two rows of pineapple

Contour trench filled with coconut husk

Capacity building programmes on soil & water conservation in the sloppy land should be

launched to cover the entire farm household.

9. Physical and financial estimate

Estimates of the proposed irrigation plan for Nicobar Islands (Rupees in Lakh)

Island name Proposed methods Units /

number

Unit

cost*

Rs.

Total

cost

Rs.

Coverage of

farm families

i) Car Nicobar

ii) Chowra group

iii) Great Nicobar

Check dams 7 5.00 35.00 42

#Lined pond (in community garden) / motor

& conveyance system (pipes) / drip

20 1.00 20.00 200

Electric motor & conveyance system (pipes) 100 0.30 30.00 50

Small rainwater harvesting structures &

water conveyance

100 0.30 30.00 200

RCC ring wells 30 2.00 60.00 120

Creation of freshwater pond in the natural

depression

2 10.0 20.00 100

Drip Irrigation system with 1-2 m head (with

existing water source) (in hact)

20 1.50 30.00 20

Total 225.00 732

* Only approximate estimate is given, the actual cost varies from place to place

10. Design and size of different water storage / irrigation units

This is proposed to be made in the coastal degraded or lowlands where sea water

intrusion and waterlogging is a problem. In addition, in slightly elevated areas, farm pond

model can be made. All the systems are designed to harvest the rain water, and support

vegetable cultivation and fish culture. The design and dimensions are given below:

1. RCC ring wells

Size = 6 m x 2.5 m

Cost = Rs. 1.72 – 2.4 lakhs

2. Lined pond at hill top

Size = 10m x 5m x 2.0 m

Cost = Rs. 1,40,000

In tribal areas = 6m x 5m x 1.5m

Cost = Rs. 65,000

3. Check dam

Width = 3 – 5 m

Depth = 1 m – 1.3 m

Downstream – upto 5 m

Upstream – 3 m

Cost = Rs. 4.5 – 5.0 Lakhs