Water Harvesting & Check Dams
Check dams range in size, shape and cost. It is possible to build them out of easily available materials. It is even possible to build some of these dams at a very little cost. The most important decision to be taken when building such a dam is its location. This decision is crucial, as the effectiveness of the dam depends on this.
Advantages of Check Dams
The advantages of check dams are that they store surface water for use both during and after the monsoon. They help in ground water recharge of the area. Recharge of water helps in raising the water table in the area. Avaiability of water ensures the icrease of agricultural yield by multi-cropping. The cost of building a check dam for irrigation of one hectare of land can vary between Rs 5000 to 8000. A large dam or canal network would cost over Rs 2 lakhs for the same purpose.
Before building a check dam the following points have to be kept in mind regarding site selection:
- Check dams can be of various sizes and built with a variety of materials including stone, clay and cement.
- Individual farmers can build small check dams of clay.
- Masonry and cement concrete structures require some degree of construction skills and high investment.
- The structure should be able to store a high volume of rain-water over a long duration of time. It should provide a long length of stored water.
- There should be a high percentage of cropped area on either side of the length of stored water.
- Minimises risk of submergence of cropped lands during flash floods. It should have a high cost-benefit ratio.