Water Era in India Rainwater harvesting systems S.Vishwanath www.rainwaterclub.org Twitter handle : zenrainman Rainwater + shallow aquifer < 1850 Surface water + shallow aquifer+ rainwater 1850-1970 Deep aquifer + surface water + rainwater 1970 --2015 Rainwater +.+ 2015 > Rainwater harvesting The method of collecting rainwater from purpose built catchments.. so for example rooftop rainwater harvesting Catchment Conveyance Filtration Storage Photo courtesy: Shree Padre
Good clean rainwater with a clean catchment and a good filter The rainwater tank is a great place to do homework
..and is multipurpose, other waters can be stored. Storage is access in areas of intermittent availability Rooftop Rainwater harvesting is especially relevant in Fluoride and Arsenic affected areas The Sachetana project of the Government of Karnataka has put 10000 rainwater tanks in households across 105 villages. This provides drinking and cooking water for the whole year. The tank size is between 5000 litres and 8000 litres. It provides 20 litres of water per day per family for the whole year. A Sachetana rainwater harvesting system with details painted on the wall
An above the ground storage tank RWH during Floods RWH During non-flood situation Quality check- using the H2S strip test for e.coli identification
Simple treatment using SODIS www.sodis.ch Urban Water and Sanitation The urban water footprint is increasing Cities search for water Manjira dam 100 km Chennai: 235 km (Veeranam lake) and now planning to go farther 300 Km (Veeranam extension project). Bangalore: 95 km (Cauvery) pumping 300 m elevation. Chennai Veeranam lake Osman Sagar Himayat Sagar Hyderabad 105 km Delhi: from Tehri dam (450 km) Map of Tamil Nadu (Thanks to Gita Kavarana ). Nagurjuna
Vaitarna cum Tansa INDORE 90 km Bhatsa YASHWANT SAGAR 30 km INDORE 105 km Mumbai 70 km Narmada river Indira Gandhi canal 204 km Jodhpur The issue Exploding water demand in cities Problems of urbanization : water shortage and flooding Need to manage water in cities holistically Rajivgandhi lift canal JODHPUR
Realities With very little catchment management New paradigm required Multiple sourcing of water Source control for flood management Institutional coordination People s participation in solution s More space for softer solutions like education Water tanker Water in the city Lakes and tanks : 261 in 1960 81 in 1997 55 in 2000 Lake development authority created to preserve and enhance surface water bodies in city Bore well Why harvest rainwater? Provides supplemental water for city Recharges groundwater potential lost due to urban crusting Reduce ecological footprint of water (power/water nexus) Helps manage urban floods Prevents salinity ingress in coastal area
Rainfall pattern in Bangalore 30 years data MONTH DAYS QUANTITY (mm) JAN 0.2 2.70 FEB 0.5 7.20 MAR 0.4 4.40 APR 3.0 46.30 MAY 7.0 119.60 JUN 6.4 80.80 JUL 8.3 110.20 AUG 10.0 137.00 SEP 9.3 194.80 OCT 9.0 180.40 NOV 4.0 64.50 DEC 1.7 22.10 TOTAL 59.8 970.00 Local hydrologic cycle seeking bio mimicry with rainwater harvesting Hydro-flows Surface runoff 15 90 Recharge 10 5 Evapo-transpiration 75 5 The aim of rainwater harvesting is bio-mimicry.
Rain barrel : easiest way to begin rainwater harvesting Details of a rain barrel Plastic basket filter Aluminium basket filter.
Rain barrels at work Rainwater harvesting in an industry 4 acres > objective 0% runoff Rain Barrels harvesting rooftop rainwater EVERY ROOF CAN BE A CATCHMENT The new rainwater harvesting bye-law By December 31 st 2011 For every plot create recharge or storage @ 20 litres per square metre of roof area @ 10 litres per square metre of paved area Minimum depth of recharge well 3 metres About 50,000 buildings now have rainwater harvesting..another 50,000 expected by year end.
Aerial View of Theme Park Training for young plumbers Creating groundwater banks the use of the aquifer. A good hydro-geological study a prerequisite for artificial recharge using harvested rainwater
Excavation The other key objective of rainwater harvesting is to keep the 500,000 bore-wells with a sunk cost of Rs 5000 crores alive and well The excavation should reach porous soil / weathered rock / fracture. Digging the pit Filling of the pit Finished recharge pit Backfilling. Round hard material. Smaller stones on top
The making of a recharge well Don t forget the maintenance Pit and concrete rings The pit has reach the silt layer Placing of the rings Recharge wells in storm-water drains
Reflective paints but also potable rainwater A flourishing rainwater filter market And a technology that helps Reserving 5 % of any space for water From a plot to the city
A recharge well in an IT office