Question

Rain water harbesting various techniques related to urban n rural areas

Answer 1

echniques of Rain Water Harvesting in Urban and Rural Areas ASHWIN BHAVSAR NOVEMBER 2015 2. What is Rain Water Harvesting ? a. Conscious collection and storage of rain water for drinking, domestic purposes and irrigation is termed as rain water harvesting. b. It is a process of artificially enhancing ground water recharge at a rate exceeding natural rate of recharge by putting proper structures. 3. Why to harvest rainwater ? a. To conserve surface water run-off during monsoon and to augment ground water table. b. To improve quality of ground water. c. To save energy in lifting water : 1m rise in water level saves 0.4kWh of energy. d. To reduce soil erosion e. Prevention of sea water ingress in coastal areas. f. Decrease in choking of storm water drains and flooding of roads g. To create a culture of water conservation 4. Rain water harvesting in urban area and rural area: Urban Area Rural Area Roof top rain water/run-off harvesting through Rain water harvesting through • Recharge Pit • Gully plug • Recharge Trench • Contour bunding • Tube well • Check dam/Nala bund • Recharge well • Percolation tank • Recharge shaft • Dug well recharge • Sub surface dyke (U.G.C.D) 5. Salient features of Ground water recharge techniques:  Quantum of water to be recharged is large.  Space available for recharge is also in plenty.  Therefore, surface spreading techniques are common for rural ground water recharge.  Watershed is considered as a unit. 6. Techniques for Ground water recharge in rural areas:  Built along hilly slopes across gullies/ small streams using locally available stones, clay etc.  Better selection where slope breaks so as to have some storage behind  Prevents soil erosion and conserves soil moisture 1.Gully Plug 7.  These are suitable in low rain fall areas by constructing bunds on sloping grounds all along the contour of equal elevation  Flowing water is intercepted before it attains erosive velocity by keeping suitable spacing between bunds  Effective method to conserve soil moisture in watershed for long duration  Spacing between two bunds depends on slope, area and permeability of soil 2. Contour Bund