IN SEARCH OF WAYS FOR IMPROVING THE TANK IRRIGATION SYSTEMS

SESSION S3:

WATER USE EFFICIENCY OF IRRIGATION SYSTEM

R.VENKATASAMYProgramme Advisor,

DHAN Foundation, Madurai, INDIA

INDIA WATER WEEK 2013April 9, 2013, New Delhi

Basics of Irrigation Tanks in India

Earthen bunded small water harvesting structures formed in natural depressions of land to catch and store rainfall run-off and soil during intensive spells of monsoon rainfall facilitating multiple uses.

Ingeneously formed by native rulers & Chieftains over the past several centuries

Toposheet showing the Tank population

388 Tanks in an Area of 104.66 sq.km

There exist about 1,40,000 tanks in South India

Source: NRSA

Size distribution of tanks

Size

class

(ha)

<40 ha

(Nos &

%)

40-200

(Nos &

%)

>200

(Nos &

%)

AP70474 10252 961

86.3% 12.6% 1.2%

KAR35235 2605 288

92.4% 6.8% 0.8%

TN30263 8405 534

77.2% 21.4% 1.4%

Panoramic Remote Sensing

Map of Cascades

of Irrigation Tanks in TN

Nature of Tank Systems• Smaller in size and larger in number with wider

geographical distribution. Amenable for efficient de-centralised management.

• Synergy in water harvesting as the tanks are connected in chain.

• Higher irrigation efficiency due to smaller distribution network with gravity flow.

• Earlier, owned, maintained and managed by village institutions by collecting revenue through their “multiple uses”. Now owned and maintained by Government.

Multiple Uses of Tank systemsGeneral Services:•Irrigation, flood moderation, drought mitigation, ground water recharging; fish rearing, domestic & cattle use, tank-bed for cultivation & grazing.•Collects and stores top soil eroded from agrl. lands for re-use.

Eco-system Services: •Provisioning services : Fresh water, food, fiber, fuel,..•Regulating services : Regulation of climate& natural hazards, water purification…•Cultural services : Spiritual, recreational, aesthetic..•Supporting services : Sediment reduction,

accumulation of organic matter..

Declining Status of Tank Systems Declining trend of tank irrigation in India (%):

Source 1960-61 1980-81 1999-2000

Canals 42.05 39.40 31.29

Tanks 18.50 8.24 5.18

Wells 29.56 45.70 57.81

Others 9.89 6.66 5.73

State

1993-94 2004-05

Tank irrigated area

in ha (‘000s)

% of NIA

Tank irrigated

area in ha (‘000s)

% of NIA

Tamilnadu 668 23.9 465 17.6

Andhra Pradesh 633 16.3 477 12.3

Karnataka 273 11.7 177 6.3

Declining trend of tank irrigation in South Indians States (%):

Causes for the Declining Status

Poor performance:•Reduced inflow due to changes in the catchment areas, silting& encroachments in the supply channels, de-linking of supply chain, etc.•Reduced storage, silting& encroachments in the water spread area, leakages in the structures, etc.

Poor maintenance:•Lesser allocation of funds and lack of supervision by Govt., as the tanks are widespread.•As the tank-fed agriculture is more risky and not remunerative, lack of interest among farmers for maintaining the tanks owned by the Govt.•Heterogeneity among the users of the tanks.

Ways for Sustainable improvement of Tank Systems

1.Tank rehabilitation programs:Southern states started rehabilitating the tanks after late 1980s.Though planned well, actual execution focused mainly on structural improvements. Relying on user’s co-operation rather than their participation.

Suggestions:

•Sub-basin level water balance study to select tanks having adequate water resources for rehabilitation .

• Encroachment eviction and ensuring safeguard for the future. Growing plants in between MWL&FTL.

•Securing real participation of people with commitment to engage common paid irrigators for each tank.

Ways for Sustainable improvement of Tank Systems

• Involving Panchayats (the rural local Govts.) for facilitating people’s participation.

• Promoting dry land horticulture in the command areas of high level sluices.

2.Research Needs:Exclusive research on tank irrigation and tank-fed agriculture

for enhancing crop productivity to offset the loss during the low rainfall years.

• Tank census for appropriate development planning.• Evolving micro irrigation system suitable for turbid tank

water .• Tank eco-system based research to value the eco-system

services.