Check dams
A check dam is a
temporary structure made of stone and wood or a permanent structure made of
cement and concrete, constructed across a drainage basin to prevent soil
erosion by reducing water flow velocity. Construction of check dams across
first-order streams/ gullies serves as an effective water harvesting structure.
Check dams control runoff, facilitate percolation of water and help to recharge
nearby wells on both sides of the streams. These structures are suitable to
conserve excess runoff water generated in seasonal streams of hill areas.
Harvested water can be used for agricultural purposes during long dry spells. This technology reduces the velocity of runoff by 11%. For protecting soil erosion near the check dam, climbers like Hedra helix, Smilux sp.;
grasses like hybrid napier and tree species like Quercusincana and Morus alba can
be planted. Besides its role as a rainwater harvesting structure in hilly
terrain, a check dam is built on a stream with the help of ground material,
stone and mud-filled wall to recharge the GW aquifer. It stops the runoff water
and has a little storage. This dam should be constructed in a sequence at a
proper distance in the stream. The flow of surface water is hindered, water
remains on permeable soil and rock surface for a longer time to recharge the
groundwater. This method of GW recharge is suitable for the region with an
annual rainfall of 900 mm. This type of structure is recommended where the rock
strata are sufficiently porous for groundwater recharge through ponded water.