In India, rainwater harvesting is an ancient tradition. From as far back as 4500 BC, the simplest of earthworks in Thar Desert and Rajasthan would harvest water from the falling rain.
1. Johads of Rajasthan:
Johads are small earthen bunds or round ponds or check dams that capture and conserve rainwater, improving percolation and groundwater recharge. The last sixteen years since 1984 have seen the revival of some 3000 johads spread across more than 650 villages in Alwar district, Rajasthan.
This has resulted in a general rise of the groundwater level by almost 6 metres and a 33 per cent increase in the forest cover in the area. Five rivers that used to go dry immediately after the monsoon have now become perennial. One such river that has come is the River Arvari.
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2. Kunds/Kundis:
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A kund or kundi looks like an upturned cup nestling in a saucer. These structures harvest rainwater for drinking, and dot the sandier tracts of the Thar Desert in western Rajasthan and some areas in Gujarat.
Essentially a circular underground well, kunds have a saucer-shaped catchment area that gently slopes towards the centre where the well is situated. A wire mesh across water inlets prevents debris from falling into the well-pit.
The sides of the well-pit are covered with (disinfectant) lime and ash. Most pits have a dome-shaped cover, or at least a lid, to protect the water. If need be, water can be drawn out with a bucket. The depth and diameter of kunds depend on their use (drinking, or domestic water requirements).
3. Tankas:
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Tankas (small tank) are underground tanks, found traditionally in most Bikaner houses. They are built in the main house or in the courtyard. They were circular holes made in the ground, lined with fine polished lime, in which rainwater was collected.
Tankas were often beautifully decorated with tiles, which helped to keep the water cool. The water was used only for drinking. If in any year there was less than normal rainfall and the tankas did not get filled, water from nearby wells and tanks would be obtained to fill the household tankas.
In this way, the people of Bikaner were able to meet their water requirements. The tanka system is also to be found in the pilgrim town of Dwarka where it has been in existence for centuries. It continues to be used in residential areas, temples, dharamshalas and hotels.
4. Eri:
The kings of the South India had built small and large open tanks called Eris, and ponds and lakes. These tanks, temple ponds and lakes formed a complete collection and storage system. If a tank overflowed, the water would flow through a canal to another tank at a lower level.
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Approximately one- third of the irrigated area of Tamil Nadu is watered by Eris (tanks). Eris have played several important roles in maintaining ecological harmony as flood- control systems, preventing soil erosion and wastage of run-off during periods of heavy rainfall, and recharging the groundwater in the surrounding areas.
The presence of Eris provided an appropriate microclimate for the local areas. Without eris, paddy cultivation would have been impossible. Till the Britishers arrived, local communities maintained Eris. Historical data from Chengalpattu district, for instance, indicates that in the 18th century about 4-5 per cent of the gross produce of each village was allocated to maintain Eris and other irrigation structures.
Assignments of revenue-free lands, called manyams, were made to support village functionaries who undertook to maintain and manage Eris. These allocations ensured eri upkeep through regular desilting and maintenance of sluices, inlets and irrigation channels.
The early British rule witnessed disastrous experiments with the land tenure system in quest for larger land revenues. The enormous expropriation of village resources by the state led to the disintegration of the traditional society, its economy and polity. Allocations for maintenance of Eris could no longer be supported by the village communities, and these extraordinary water harvesting systems began to decline.