Abstract: Pollutant sources can be identified from analysis of online monitoring data collected in a river
reach at its downstream by solving inverse problems of the sources, which provides basic information for
control of pollutant sources and protection of headwaters area. For unsteady flow in 1D channel, a new
FDM-SIM method combining finite difference method with simplex algorithm is presented herein. This
method was applied to determination of pollution sources and their parameters, and validated by two
numerical cases. The results indicate that the method is very useful in identification of pollution sources and
in coupled inversion calculation for coefficients of the sources and water quality.