Tanks are earthen bunded small water storage structures constructed across the slopes to capture rainwater runoff.
Bird's Eye View
There is a lot more to tanks than just the pleasant sight of brimming water. For centuries, tanks were village properties that supported the villagers as a major source of livelihood in peninsular India. Historically, kings, local chiefs and philanthropists developed tank irrigation. Village assemblies, called gramasabhas existed all over the south in different forms. They ensured an optimal use of common resources.
Hoary inscriptions state that the management of irrigation was one of the major agenda of village assemblies. The revenue generated by the villages apart from the corpus funds they had was also used by the assemblies to protect the tanks. The assemblies ensured that the water resource was sustainable.
When the management of these common properties and tanks was centralised, there was no resource left to protect them. This hit the livelihood of farmers and weakened the village economy.
The Vayalagam Tankfed Agriculture Development Programme (VTADP) works for the development, management and conservation of tank systems. DHAN Foundation and its VTADP firmly believe that reviving the local management of the tank offers a long-term solution to the problem of water scarcity.
Recent decades have witnessed a significant decline in the role of tanks and other minor surface irrigation works.
NIA by tank
% of NIA
1950-51 – 1959-60
1960-61 – 1969-70
1970-71 – 1979-80
1980-81 – 1989-90
A Quick Look
India has a long history of people’s involvement in rainwater harvesting to meet the local needs, especially for farming. The country has a unique climate with intense monsoon for some weeks followed by long droughts. Our erstwhile rulers and chieftains, together with local craftsmen and villagers ingeniously set up irrigation tanks that were rainwater harvesting structures. These tanks were earthen-bunded reservoirs built to take advantage of the natural depressions and mounds, particularly the undulating topography of the Deccan Plateau that provided a good base for these simple, but innovative water harvesting structures.
Most tanks were linked in chains called tank cascades, where upstream tanks passed their surplus to tanks downstream. A typical tank cascade will have eight to ten linked units. Tanks have been the most important source of irrigation, for recharging ground water, offering sanctuary to birds, for domestic use of people and a source of drinking water for both people and animals, as well as a source of silt and sand for construction.
A tank complex comprises the catchment area, supply channels, water spread area, earthen bunds, outlet structures (sluices), field irrigation channels, surplus weir and the command area.
The land from which the surface runoff drains into any stream or reservoir is called the catchment basin and the area of this tract is its catchment area. Supply channels direct the water from the catchment basin to the tanks Water spread area is the area over which the runoff spreads on the upstream side of an embankment Tank bund is a mud mound formed across a sloping land to store the surface runoff Sluice is the water regulator to control the outflow Surplus weir is a sub-system through which excess water flows out of the tanks Field irrigation channels direct irrigation water from the sluice outlet to the fields
Before the British usurped and consolidated the various power centres in India, the community owned and kept the tanks in good shape. After the British took over the tanks as property of the State for revenue purpose, the centralised management prevented the local community from collectively maintaining and managing them. Over decades, the farmers began to expect the Government to do every bit of work. The collective effort by the people to preserve the tanks declined. This accelerated the ruin of these structures.
After Independence the Government concentrated on major irrigation schemes. Tank-fed agriculture lost its status and that hit farming in many areas. Rich farmers in tank command areas opted for bore wells. This further jeopardised the collective community action needed to revive the glory of the tank systems.
People’s apathy to collective responsibility led to:
If you think about it you will agree that the frequent droughts in the country could be handled by simple and robust solutions. Since there are tanks all over the country, these public properties needed to be protected through conservation measures. Unfortunately, more focus is now given to creating new structures that either seem to be short-lived or never serve the purpose they are meant for.
The trend shows a steady decline in area under tank-fed agriculture and an increase in land irrigated with ground water. The higher use of ground water for irrigation is raising the cost of production. The option is unsustainable not only because ground water tables are falling rapidly but also bankruptcy of farm households.
An analysis shows that village tanks and ponds offer good scope for ground water recharge and to stabilize the farm productivity. The VTADP was begun in 1992 in Madurai district after analysing chronically drought-prone areas of Tamil Nadu. The aim has been conservation, development and management of tank systems and improving the livelihood of farmers. The programme was later implemented in other locations that had similar agro climatic, geological and sociological conditions.