Rain water harvesting is the process of collecting and storing rainwater before it reaches the aquifer. It can help address issues of inadequate surface water, declining groundwater levels, and reduced groundwater recharge due to urbanization. Traditional methods of rainwater harvesting in India include baowdis, johads, and kunds. Roof rainwater harvesting systems involve catchment areas, conduits, filters and a storage facility. Surface runoff harvesting collects water flowing along the ground into reservoirs. If implemented properly, even 100mm of annual rainfall can be sufficient and rainwater harvesting has benefits like increasing groundwater supplies, reducing soil erosion, and boosting crop production. It is a low-cost method that uses local materials

1. PRESENTATION
ON
RAIN WATER HARVESTING
PREPARED BY
prashanth Halemane.

2. RAIN WATER HARVESTING
A NOBLE GOAL A COMMON RESPONSIBILITY

3. WHAT IS RAIN WATER HARVESTING
 Rainwater 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.

4. WHY RAIN WATER HARVESTING :
 Surface water is inadequate to meet our demand and
we have to depend on ground water.
 To arrest ground water decline and augment ground
water table
 To beneficiate water quality in aquifers
 To conserve surface water runoff during monsoon
 To reduce soil erosion
 Due to rapid urbanization, infiltration of rain water
into the sub-soil has decreased drastically and
recharging of ground water has diminished.

5. RAIN WATER PATTERN IN INDIA
 Total annual rainfall in India: 400 million hectare-
meters (area x height)
 India’s area: 329 million hectares
 If evenly spread, average height: 1.28m
 Actual distribution:
 Highly skewed area-wise
 Thar desert receives less than 200mm annually, while
Cherrapunji receives 11,400mm
 But almost every part of India receives at least 100mm
annually
 Key: even 100mm annual rainfall sufficient if
harvested properly and where it falls

6. RAIN WATER HARVESTING
TECHNIQUES :
 Roof top rainwater harvesting.
 Surface runoff harvesting .

7. ELEMENTS OF ROOFTOP RWH
 CATCHMENT
 COUNDITS
 FILTERS
 STORAGE FACILITY

8. METHODS OF ROOFTOP RWH
 Storage of direct use
 Recharging ground water aquifer
- Recharging dug wells
- Recharging pits
- Recharging tube well

9. 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 collecting
rainwater for irrigation, water
flowing along the ground during
the rains will be collected to a
tank below the surface of the
ground..

10. TRADITIONAL RWH STRUCTURE
BAWODI:
 Traditional step wells are
called vavadi in Gujarat, or
baoris or bavadis in Rajasthan
and northern India.
 They were secular structures
from which everyone could
draw water.
 Most of them are defunct
today.

11. JOHADS
A 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.

12. Kunds
 Covered underground tank,
developed primarily for tackling
drinking water problems.
 Usually constructed with local
materials or cement, kunds were
more prevalent in regions where
groundwater is saline.
 Before the onset of rains every year,
meticulous care was taken to clean
up the catchment of the kunds.
 Cattle grazing and entry with shoes
into the catchment area of the
kunds was strictly prohibited.
 The proximity of a kund to the
house or village saved time and
effort in searching for drinking
water.

13. USES OF RAINWATER HARVESTING
 Domestic Use
 Agricultural Use
 Increase groundwater supplies

14. POTENTIAL OF RWH
 Impacts on downstream flows.
 Reduce soil erosion.
 Increase the crop production.
 Increase infiltration and groundwater recharge.
 Improve food & economic security.

15. ADVANTAGE
 It 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.

16. RWH: A NOBLE GOAL
A COMMON RESPONSIBILITY

17. THANK YOU
FOR
ATTENTION

18. 1.Prashanth Halemane
2.Vinay Vihari…………...