This paper deduce water retention from water inflow the river,which generated by hydrological model according to underlying condition,to get drainage modulus,on full consideration of reservoir action.

• 本文根据圩区下垫面条件进行产汇流计算,入河流量扣除滞蓄量得到排涝模数,充分考虑到圩内河道的调蓄作用。