Post edited 3:54 am – January 9, 2012 by JollyMark
Rain water can be harvested for two purposes i.e. storing water for ready use in containers above or below the ground and charging into the soil for withdrawal later. It can be harvested from rooftops, paved or unpaved areas, water bodies and storm water drains. The catchment area is effectively available free of cost if the buildings are provided with impervious roofs and they provide a supply at the point of consumption. Paved and unpaved areas include landscapes, open fields, parks, storm water drains, roads and pavements and other open areas which can be effectively used to harvest the runoff. Ground which is used as a collecting surface for rainwater has the advantage of a larger area from which water can be collected. Areas of low rainfall must make use of this advantage. Water bodies like lakes, tanks and ponds store immense amount of rainwater. The harvested amount of rainwater can be used to meet water requirements of the city and for recharging ground water aquifers. If the network of storm water drains in residential areas is maintained neatly, they also offer a simple and cost effective means for harvesting rainwater.
The rainwater pattern and potential in a particular region determines whether to store or recharge water. The sub surface geology should also be taken into consideration in making a decision. Ground water recharge is usually practiced in areas where the total annual rainfall occurs during three or four months. Places where rain falls throughout the year except for a few dry periods, a small sized tank can be used for storing rainwater. Kerala is one of the places which receive high rainfall almost throughout the year. Almost each of the Kochi flat is now provided with rain water harvesting systems to make utmost usage of rainwater.