Flood and waterlogging monitoring and analyses based on SSM/I data in Huaihe River Basin
基于SSM/I数据的淮河流域洪涝监测分析

The estimation of soil wetness variations is of importance to improve the reliability of flood warning.In this paper,the coarse spatial passive microwave data was used to monitor large area flooding and soil moisture because of the ability of the microwave signal to penetrate through cloud and provide all-day data and because of its sensitivity to surface moisture and wate.It can effetively reveal large-scale soil wetness and flood patterns under cloudy and rainy conditions.Polarization Ratio Variation Index(PRVI) was presented on the basis of polarization ratio index(PRI) calculated by the horizontal and vertical polarization brightness temperature data and Robust AVHRR Techniques(RAT).Nearly 18-year(1988-2005) PRVI serials were calculated from Special Sensor Microwave/Image(SSM / I) data in the Huaihe River Basin.PRVI datasets were obtained in the ten-day periods from June 21 to July 31 in the flood season.Several important flooding events in the Huaihe River Basin from 1988 to 2005 were described,and the flooding events of 1991 and 2003 were especially analyzed.We found that the serious flood and waterlogging disasters could be reflected by the formation of a higher PRVI value zone in the buffer along the Huaihe River mainstream extending 100 km north and basin boundary south.The higher PRVI value zone was consistent with the historical records.Furthermore,the reason for the formation of higher PRVI value zones was analyzed.The zone included many flood detention areas,lakes and bayous and low-lying lands.The higher PRVI value zone may be used as an indicator for flood forecast.Preliminary results confirmed the reliability of the proposed method.It is of great significance to the prevention and mitigation of flood and waterlogging disasters.