science ppt
TRANSCRIPT
Seminar on : RAIN WATER HARVESTING
Presented by: Vivekanand. S.Murashillin Xth b Roll no:24 subject : science
RAIN WATER HARVESTING
SAVE WATER:RAIN WATER HARVESTING
WHAT IS RAIN WATER HARVESTINGRainwater harvesting is the accumulating and storing of rainwater for reuse before it reaches the aquifer.
The principle of collecting and using precipitation from a catchments surface
WHY RAIN WATER HARVESTINGSurface water is inadequate to meet our demand
and we have to depend on ground water.To arrest ground water decline and augment
ground water tableTo beneficiate water quality in aquifersTo conserve surface water runoff during
monsoonTo reduce soil erosionDue to rapid urbanization, infiltration of rain
water into the sub-soil has decreased drastically and recharging of ground water has diminished.
RAIN WATER PATTERN IN INDIATotal annual rainfall in India: 400 million
hectare-meters (area x height)India’s area: 329 million hectaresIf evenly spread, average height: 1.28mActual distribution:
Highly skewed area-wiseThar desert receives less than 200mm annually,
while Cherrapunji receives 11,400mmBut almost every part of India receives at least
100mm annuallyKey: even 100mm annual rainfall
sufficient if harvested properly and where it falls
RAIN WATER HARVESTING TECHNIQUES :Roof top rainwater harvesting.
Surface runoff harvesting .
ELEMENTS OF ROOFTOP RWHCATCHMENT
COUNDITS
FILTERS
STORAGE FACILITY
METHODS OF ROOFTOP RWHStorage of direct use
Recharging ground water aquifer - Recharging dug wells - Recharging pits - Recharging tube well
SURFACE RUNOFF HARVESTING
Harvesting of surface runoff and storage of the same into reservoirs such as water pans makes it available for use when required.
In this method of collectingrainwater for irrigation, water flowing along the ground during the rains will be collected to a tank below the surface of the ground..
TRADITIONAL RWH STRUCTUREBAWODI:Traditional step wells are calledvavadi in Gujarat, or baoris orbavadis in Rajasthan and northern India.
They were secular structures fromwhich everyone could draw water.
Most of them are defunct today.
JOHADSA johad is a crescent-shaped bund which is built across a sloping catchment to capture the surface water before it runs off.
Water accumulating in the johad percolates in the soil to augment the groundwater. The groundwater then can be used when there is no rainfall.
USES OF RAINWATER HARVESTING
Domestic Use
Agricultural Use
Increase groundwater supplies
POTENTIAL OF RWH
Impacts on downstream flows.Reduce soil erosion.Increase the crop production.Increase infiltration and groundwater
recharge.Improve food & economic security.
ADVANTAGEIt uses local construction materials and labor.Sources of energy are not needed to operate
the systems. The owner/user can easily maintain the
systems. The water is convenient and accessible;
valuable time and effort are saved in collecting and/or hauling water.
It provides a supply of water to meet future agricultural needs.
RWH: A NOBLE GOAL
A COMMON RESPONSIBILITY
Thank You