Assessment of ecological water requirement of typical crops in the small watershed of Three Gorges reservoir region

By using Penman-Monteith Formula, crop reference evapotranspiration in Xiaziling small watershed in Three Gorges Reservoir was calculated; and adopting field observations and experimental data, it could obtain the crop coefficient. Then actual evapotranspiration, which could reflect water requirement, is calculated by coupling analyzing them. Results present that: water supply due to rainfall is greater than water requirement of different crops in most months, and redundant supply account for 50-70% of annual precipitation. But there have relative different between monthly rainfalls. So, in whole growth stage of different crops, there is still exist water shortage (35-135mm). So it could adjust regional runoff and build drainage system and water storage system, which could give replenishment for insufficient water supplement.