MANAGEMENT OF RUNOFF STORED IN SMALL TANKS FOR TRANSPLANTED RICE PRODUCTION IN THE MIDHILLS OF NORTHWEST HIMALAYA

Scarcity of water in upland areas limits the growing of transplanted r ice and the yield of rice grown under rainfed conditions is very low. As the first priority for the use of runoff recycling based water reso urces is in the dry season followed by the monsoon season, a strategy has been developed to use the surplus water (occurring during the earl y monsoon season) to grow transplanted rice without compromising the d ry season irrigation. Field experiments revealed that under the mid-hi ll conditions, transplanted rice can be grown as transplanted in 5 cm standing water and thereafter rainfed, requiring only 3.0-3.5 cm of wa ter with a yield reduction of about 25% as compared to generally recom mended intermittent submergence (2 days after the disappearance of wat er) requiring 100-130 cm of water. However, the reduction in yield was not significant if 1 week of initial pending just after transplanting was created. Based on rainfall-runoff analysis, graphs were developed for runoff and volume of water available in water tanks in different durations of early monsoon periods, command-catchment area ratio and t he volume of water available after irrigation which is to be used in d ry season, as a function of runoff curve numbers. These graphs can be consulted directly to plan irrigation systems for transplanted rice in upland areas.