15 Feb CHECK DAMS: A BOON TO SOCIETY
CHECK DAMS: A BOON TO SOCIETY
From an environmental point of view, check dams are simple to build water harvesting structures and all the governments should be promoting this.
CDs can be built in a small watershed to prevent erosion, slowing down of water flow and hence opportunity for more recharge. In the trunk stream or in the main channel, CDs help again to slow down the base flow and not the flood waters. The former again is a forcing of more recharge opportunities. In fact it is like the classical pond that used to be the source for irrigation in lean months. The only difference being the placement of the pond as a no-seepage-barrier as opposed to check dams. The CDs are usually build with sand bags, rubble packs inside wire net or simple stacking of rubble as a dry rubble wall across a stream. In fact it is very much similar to a weir.
Check-dams, like tubewells, are a decentralized form of irrigation under the control of farmers, allowing them to make micro-adjustments to their watering regimes in response to local factors and thereby to improve yields. Such being the advantages the announcements by the ministers are bound to become a far cry. The CDs are in fact promoted by the ministry of water resources and is practiced all over India where there is acute scarcity of water.
In fact the print media should come forward and argue for building more check dams for water conservation as well as for rejuvenation of the fresh water ECOSYSTEMS. It is bound to be one of the ways of rehabilitating the ravaged rivers of Kerala. I shall recommend building of such CDs in the midland of Kerala in the midland segment of the 41 river channels of Kerala as well as in the tributaries.
CDs do not prevent through flow. Only thing it does is slow down the speed of the current. In the semi-arid California state many rivers display boldly several CDs along the course. The intention there is to slow down the flow to enhance recharge duration into the subsurface aquifers.
The TATA initiative to build CDs should there fore must be taken as a welcome move by the authorities. The CDs are in fact permeable structures and not large dam like barriers. I will say three cheers to TATAs for initiating the water conservation practices in their property under lease