TankasTankas(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 raiwater was collected.Tankaswere 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 thetankasdid not get filled, water from nearby wells and tanks would be obtained to fill the householdtankas. In this way, the people of Bikaner were able to meet their water requirements. Thetankasystem 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,dharamshalasand hotels.

KhadinAkhadin, also called adhora, is an ingenious construction designed to harvest surface runoff water for agriculture. Its main feature is a very long (100-300 m) earthen embankment built across the lower hill slopes lying below gravelly uplands. Sluices and spillways allow excess water to drain off. Thekhadinsystem is based on the principle of harvesting rainwater on farmland and subsequent use of this water-saturated land for crop production.

First designed by the Paliwal Brahmins of Jaisalmer, western Rajasthan in the 15th century, this system has great similarity with the irrigation methods of the people of Ur (present Iraq) around 4500 BC and later of the Nabateans in the Middle East. A similar system is also reported to have been practised 4,000 years ago in the Negev desert, and in southwestern Colorado 500 years ago.

Urban rainwater harvestingUrban centres in India are facing an ironical situation today. On one hand there is the acute waterscarcityand on the other, the streets are often flooded during the monsoons. This has led to serious problems with quality and quantity of groundwater.

This is despite the fact that all these cities receive goodrainfall. However, this rainfall occurs during short spells of high intensity. (Most of the rain falls in just 100 hours out of 8,760 hours in a year). Because of such short duration of heavy rain, most of the rain falling on the surface tends to flow away rapidly leaving very little for recharge of groundwater. Most of the traditional water harvesting systems in cities have been neglected and fallen into disuse, worsening the urban water scenario. One of the solutions to the urban water crisis israinwater harvesting- capturing the runoff.

Water harvesting system atCSE's office in Delhi

This is practiced on a large scale in cities like Chennai, Bangalore and Delhi where rainwater harvesting is a part of the state policy. Elsewhere, countries like Germany, Japan, United States, and Singapore are also adopting rainwater harvesting.

Why to harvest rain?

In areas where there is inadequate groundwater supply or surfaceresources are either lacking or insufficient, rainwater harvesting offers an ideal solution.

Helps in utilising the primary source of water and prevent the runoff from going into sewer or storm drains, thereby reducing the load on treatment plants.

Reduces urban flooding.

Recharging water into the aquifers help in improving the quality of existing groundwater through dilution.

Jal Yodhas

When it comes to the Indian sub-continent, given the delay in implementing plans to conserve natural resources, people prefer to depend on themselves. Jal Yodhas (Water warriors) is a tale of individual efforts that can act as a precursor to bring a shift in peoples' attitude towards conservation of natural resources, particularly water. This section is about ordinary men with extraordinary will in the context of water harvesting. Initial failures did not deter these men of steel who in most cases have faced rebellion from their own people.Meet the Jal Yodhas... Water conflicts

Summer comes to India every year. Along with it comes water crisis

As wells, ponds and taps dry up, women begin to walk the village streets and city roads with pots and pitchers looking for a water-point. As municipality water-tankers and government-run water trains begin to traverse the length and breadth of the country, people gather on street corners, village squares and in front of municipality offices. They murmur, growl, throw stones, and fight...

Water is becoming a cause for social conflicts

Protests, demonstrations, road-blockades, riots. City-dwellers against farmers. Villages against towns. Towns against cities. Citizens against the government. People against people. Increasingly, these (usually local) conflicts are taking on the general shape of a bitter war for water.