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INDIA WATER WEEK 2013 April 9, 2013, New Delhi

SESSION S3: WATER USE EFFICIENCY OF IRRIGATION SYSTEM

IN SEARCH OF WAYS FOR IMPROVING THE TANK IRRIGATION SYSTEMS R.VENKATASAMY

Programme Advisor, DHAN Foundation, Madurai, INDIA


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


Size distribution of tanks Size

<40 ha

40-200

class

(Nos &

(Nos & (Nos &

(ha)

%)

%)

%)

70474

10252

961

86.3%

12.6%

1.2%

35235

2605

288

92.4%

6.8%

0.8%

30263

8405

534

77.2%

21.4%

1.4%

AP

KAR

TN

>200

Panoramic Remote Sensing Map of Cascades of Irrigation Tanks in TN

Source: NRSA


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 systems General Services: •Irrigation, flood moderation, drought mitigation, ground water recharging; fish rearing, domestic & cattle use, tankbed for cultivation & grazing. •Collects and stores top soil eroded from agrl. lands for reuse. 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 Canals Tanks Wells Others

1960-61 42.05 18.50 29.56 9.89

1980-81 39.40 8.24 45.70 6.66

1999-2000 31.29 5.18 57.81 5.73

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

1993-94 State

Tank irrigated area

% of NIA

in ha (â&#x20AC;&#x2DC;000s)

Tamilnadu Andhra Pradesh Karnataka

668 633 273

2004-05 Tank % of irrigated NIA area in ha (â&#x20AC;&#x2DC;000s)

23.9 16.3 11.7

465 477 177

17.6 12.3 6.3


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 cooperation 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.


IN SEARCH OF WAYS FOR IMPROVING THE TANK IRRIGATION SYSTEMS