Central Ground Water Board North Central Chhattisgarh Region Raipur
		WWW.CGWBRaipur.gov.in

Objectives

Augment recharge to surface and ground water storage for sustainability
Conserve water by arresting surplus flow to river and thus avoid wastage to sea during rainy period
Save flooding cities,towns and villages by arresting storm flow
Reduce soil erosion
Improve environment of cities and towns
Improve water quality

Components

Rainfall (Raifall is the source water for harvesting)
Catchment (This is the are over which rainfall occurs)
Conveyance(Method by which the water is to be carried from the catchment to the storage structure)
Storage (May be surface or sub surface storage tanks or the aquifers)

Methods

Depending upon the mode of catchment, conveyance and storage, there can be several methods of rainwater harvesting. The traditional rainwater harvesting structures include Kool method, bamboo method, desert kunds, temple tanks etc.Salient features of the major rainwater harvesting structures are discussed below:

Surface spreading of water in basins excavated
Highly permeable soil is a prerequisite
Two important factors are infiltration rate and horizontal water movement
Clogging and microbial activities may hamper Infiltration
Most effective when there is no impervious layer between surface and aquifer

Suitable conditions for surface spreading are rarely met
In situations, where a lensoid body of low permeability lies between the surface and the aquifer pits and shafts are more effective
Pits and shafts may be circular, rectangular or of square cross section
Excavation may be terminated just above the water table
Require maintenance because of siltation and clogging

To be provided in percolation pond/tank bed to hasten percolation effect
Applicable where the water table is very deep or an impermeable layer lies between the surface and the aquifer
A filter is to be provided to prevent the silty material from entering the tubewell
Maintenance work needed after every monsoon

Shallow depth tanks formed at appropriate places in natural or diverted water courses
Provided with a weir to allow excess water to pass through
The soil in and around the tank should be permeable for quick percolation with minimum evaporation
Existing village tanks can be modified for the purpose

Most suitable for urban areas where rooftops form clean and potential catchments
Water from the rooftop is diverted to storage tanks or is used to recharge ground water
For details go to www.CGWAindia.com