3　Applying This Model to the Fengshuba Reservoir

The total basin area of Fengshuba reservoir is 51508km2.The area of the western tributary at Tau-xi station is 1306 km2 and that of the eastern tributary at Lizhangfeng station is 1400 km2.The remaining area is 2444km2.The calculation of runoff yield in the natural state is selected as the model of runoff yield at natural storage.There are three middlesized reservoirs，56 small reservoirs and many ponds scattered in the Fengshuba basin.Their total water storage capacity is 7562×104m3.These influences should not be neglected.They become especially conspicuous when the group of reservoirs is empty at the beginning of the flood season and following long periods of drought.Hence，the influence must be taken into account when the runoff yield scheme is made.

The Fengshuba basin is divided into three units，Tau-xi，Lizhangfeng，and the local area of Fengshuba，so that the influence of reservoirs in each unit is considered separately.The respective runoff yield forecasting schemes have been made based on the data of rainfall and flood in 1977—1983.The qualified rates of runoff yield for model calibration are 90.3%，90.0%and 92.6%，respectively.In addition，these runoff yield forecasting schemes were verified using the data in 1984—1985.The qualified rates of model verification for Tau-xi，Lizhangfeng and Fengshuba are 88.9%，100%and 91.7%respectively.For the entire Fengshuba basin，the qualified rate rises from 85.1%for the previous scheme to 91.7%for the present scheme.