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
>200
class
(Nos &
(Nos & (Nos &
(ha)
%)
%)
%)
70474
10252
961
86.3%
12.6%
1.2%
AP
35235
2605
288
92.4%
6.8%
0.8%
30263
8405
534
77.2%
21.4%
1.4%
KAR
TN
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,
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
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 (‘000s)
Tamilnadu
Andhra Pradesh
Karnataka
668
633
273
2004-05
Tank
% of
irrigated
NIA
area
in ha (‘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.