RAIN WATER HARVESTING

Water is a scarce natural resource, even though 71% of land is covered by water. Only about 2.5% of the total water available on earth is fresh water and can be used for human consumption. Water has now become one of the most precious natural resources of our planet and is also becoming one of the major challenges to human survival. The demand for water is increasing rapidly while the supply of fresh potable water is decreasing.   The demand supply gap is especially acute in urban areas which has led to the indiscriminate mining of ground water with no restrictions. Once productive wells are drying up, especially in summer when the demand is very high.

As compared to many other countries, India receives sufficient rainfall; it is in fact the second wettest country in the world. However, rapid urbanization of most cities in India has affected the quantity and quality of surface and ground water as evidenced from lowering of ground water levels in most cities. Coupled with this, there is a lot of uncertainty in monsoon patterns in recent years. This has in turn put immense pressure on the requirement of water resources both in rural as well as urban areas and leading to over-utilization of ground water. According to the Ministry of Water Resources of India, the domestic demand is expected to grow by 40 percent from 41 to 55 trillion litres while irrigation will require only 14 percent more ten years hence, 592 trillion litres up from 517 trillion litres currently.

The demand supply gap is especially acute in urban areas which has led to the indiscriminate mining of ground water with no restrictions. It is no surprise that the ground water level is decreasing day by day.

One small measure to mitigate this is the recharge of ground water during the monsoons using Rain-water harvesting systems (RWH).  Understanding the potential for RWH using the wells is the first step in fulfilling a social need of RWH using existing wells in the Pune urban region. Rain-water can be used to replenish water storage systems artificially especially ground water, and augment scarce resources during the non – monsoon period. 

In a hard rock area like basalts, digging wells or pits is not enough to recharge the ground water. At best the shallow aquifers can be recharged. However increased urbanisation and migration to cities has led to increased construction and consequently concretising of once green areas. In such cases, a conduit (usually a dug well or bore well) is required to use the rain-water harvested for recharging. A simple method is to use existing boreholes for recharge.

It is estimated that less than 40% of the bore wells in urban areas are being used for recharge purposes.   Understanding the potential for Rain Water Harvesting (RWH) using the roof tops and existing wells is the first step in fulfilling a social need to increase availability of potable water.

At CERG, we are making a humble attempt at building awareness on this very crucial aspect of proper use and management of water resources. We now invite your whole hearted participation and support in this endeavour.