Flood forecasting for small and medium-sized rivers in ungauged basins

Abstract

The study of flood simulation and forecasting for small and medium-sized rivers with insufficient data is a key and difficult problem in hydrological forecasting research. Paitan River Basin in Guangzhou was taken as the target basin, and the synthetic unit hydrograph method and the hydrological similarity parameter transplantation method were applied for hydrological simulation and forecasting research. In the hydrological similarity parameter transplantation method, the Xifu River Basin is used as the reference basin. Based on the terrain index frequency analysis result of the Xifu River and Paitan River basins, it is considered that the two basins have hydrological similarity. The Xinanjiang model parameters of the reference basin are directly transplanted to the target basin for typical flood simulation and forecasting. The flood simulation result of the above two method in the target basin are compared and analyzed with the measured flood data. The result show that the parameter transplantation method based on the Xinanjiang model requires more hydrological and geographical data from the reference basin and the target basin, and has higher overall forecasting accuracy than the synthetic unit hydrograph method. The synthetic unit hydrograph method requires less hydrological and geographical data and has lower overall accuracy, but as the flood magnitude increases, the forecasting accuracy will significantly improve. Based on the applicability conditions and application effects of the above two method, a flood forecasting method for small and medium-sized rivers with insufficient data is proposed.

Keywords

Hydrological similarity / Terrain index / Parameter transplantation / Synthetic unit hydrograph / Xinanjiang model