A method for defining flood meteorological risk indices of intermediate rivers based on hydrological simulation

A method to define the flood meteorological risk rain threshold indices of intermediate rivers is presented based on hydrological simulation. Critical reference discharges for different flood meteorological risk grades are estimated with the stage-discharge curves. The 08:00BST discharge data from the three hydrometric stations located respectively in Wucha (5 566 km ²), Dongxi (3 097 km²) and Shijiao (707 km²) of Qijiang and hourly mean areal precipitation (MAP) estimated with weather radar and rain gauges from 1 May to 30 September 2009 were taken as discharge and precipitation inputs of the TOPMODEL (TOPography based hydrological MODEL). On the base of TOPMODEL hydrometric simulation, the hydrometric simulation was conducted using both the selected peak discharge processes in 2009 and designed different hourly MAP series. The relation between peak charge and accumulated MAP was obtained. According to the critical reference discharges the flood meteorological risk indices for intermediate rivers was defined. The defined flood meteorological risk indices was verified with the peak discharge processes of 2010 and results of the verification showed that the flood meteorological risk grades inferred from the risk rainthreshold indices were consistent with the flood risk grades of observed flood peaks.