Rain Water Harvesting(RWH)

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RAIN WATER HARVESTING – GIFT FROM THE SKY

Location of Bangalore City

  • Topography : Situated on undulating land intermittently dotted with low hills and valleys
  • Latitude       : 13° North
  • Longitude    : 77° East.
  • Elevation     : About 1000 meters above MSL

Climate of Bangalore City

  • Temperature       : Mean annual 24°C ;
    Extremes:15°C in winter, 37°C in summer
  • Average rainfall : 972mm (30 years average) mainly distributed over 8months – April to November
    with around 60 rainy days in a year
  • Natural Drainage Valleys :
          • Hebbal Valley
          • Vrishabhavathi Valley
          • Koramangala-Challaghatta Valley
  • Number of Lakes    : 82

Water Potential & Availability

  1. Total quantum of water potential from all the four sources – 994 million lts. per day (MLD)
  2. Actual availability of water per day

Water received             –  910 MLD
Water requirement                    – 1300 MLD
Water deficit                             –  390 MLD
As per WHO standards           –  Requirement is 135 LPCD
Availability of water is 119 LPCD                    

Population and Water demand in BBMP Area

Year Population in Lakhs Water Demand in MLD Water supply in MLD Short fall in MLD
2001 53.79 870 540 330
2010 96.00 1300 850 450
2015 100.00 1500 1470 30
2021 110.00 1800 1470 330
2036 125.00 2500 1470 1030

Water – The life

  • Water is very much essential for life
  • In the modern society water fulfills several needs
  • Water for drinking, bathing and cooking food are among the important daily needs for human kind

Water – The source

  • Fresh water is made available for consumption in  many ways
    • Natural springs
    • Step wells, Ponds & lakes
    • Canals, Rivers
    • Open wells & tube wells

Rainwater – to rely on

  1. Rain water would be the immediate resource to augment existing water supply system
  2. By Simply “Catching wherever it falls”

Bangalore has around 60 rainy days and like a clock work 85% of the rain arrives between 4p.m. and 7p.m.

Rainwater – at all places

  1. Three methods
    1. Roof top RWH
    2. Runoff RWH (landscapes, parks, storm water drains, roads, etc.)
    3. Natural storage and collection through lakes and tanks

Various stages of rainwater Harvesting