WATER MANAGEMENT FORUMThe Institution of Engineers (India)http://www.wmf-iei.org/index.php/
• Process of arresting and storing rain water forefficient application and conservation• An effective way of utilising large quantum ofwater which otherwise goes as surface runoff.• RWH has 2 components: 1) Rain water collection for storage 2) Recharging groundwater What is artificial recharge to ground water?• Process of enhancing ground water storage artificiallyat a rate exceeding natural rate of recharge• Possible by putting up small structure enabling storageand infiltration
What are the advantages of RWH & recharge? Improvement in ground water levels Enhancement of water availability in wells/ tube-wells Improvement in the quality of ground water through dilution Saving energy in lifting ground water – one meter rise in level saves 0.40 KWH of electricity Reduction in soil erosion due to reduced surface water runoff
What are the Rain Water Harvesting techniques for urbanareas? • Suitable for buildings having roof area of 100 square meters Constructed for recharging shallow aquifers Pit width 1 to 2 meter, depth 2 to 3 meter Pits to be backfilled with boulders at bottom --5 to 20 cm size, gravel in between 5-10 mm size and coarse sand at the top --1.5 to 2 mm size in graded form.
• Backfill pits for smaller roofs with brickbats/ cobbles. - Mesh to be provided at top to prevent leaves etc from falling &choking - Top sand to be cleaned periodically.- Bye-pass arrangements to be provided before collectionchamber to reject first showers Abandoned Tube –wells Can be utilised for recharging as shallow aquifers have dried up Water channelized for recharging, after silt removal from such wells 10 cm diameter PVC pipes connected to roof drains. First rains allowed to pass through bottom of drain pipe, which is closed thereafter.
Recharge Trench• Suitable for buildings having roof area of 200 square metersor more• Suited at places where shallow permeable strata exists• Half to one meter wide, one to one and a half meter deepand 10 to 15 meter long trenches
Backfilled with boulders at bottom --5 to 20 cm size, gravel in between 5-10 mm size and coarse sand at the top --1.5 to 2 mm size in graded form. Mesh to be provided at top to prevent leaves etc from falling & choking Top sand to be cleaned periodically. Bye-pass arrangements to be provided before collection chamber to reject first showers
RECHARGE WELLS/ SHAFTS Suited at places, where deeper permeable strata exists. 100 to 300 mm diameter recharge well, constructed 3 to 5meter below water level. Trench for channelizingwater to well – 1.5 to 3 mwide, 10 to 30 m in lengthconstructed. Shaft of 2 to 5 mdiameter, 3 to 5 m depth isconstructed if aquifer islocated at greater depth. Recharge well mentionedabove, is to be constructedwithin this shaft.