DESIGN OF RUNOFF RECYCLING IRRIGATION SYSTEM FOR RICE CULTIVATION

Design of a runoff-recycling-based irrigation system to provide irriga tion for rice in monsoon season is a complex problem. The irrigation r equirement, as well as the water availability in the form of runoff, v ary both in amount and time. The design of an irrigation system based on the irrigation requirement obtained from short-period experiments m ay lead to Faulty design. To overcome this, a simulation study of wate r balance of the cropped area as well as the tank has been done to det ermine the catchment command area ratio and size of the tank for a fiv e year return period. It has been found that for transplanting within optimum period, the catchment command ratio should be 5.0 or more and a tank of storage capacity of 132.6 mm will be sufficient at a return period of five years for the U.P. midhills of India. It has also been found that a short-duration variety will be more suitable for such an irrigation system.