Abstract

East river is a tributary of the Pearl River in southern China. Some of the most developed cities are located in the East River delta. Flooding has been causing disasters to this area. This paper develops a flooding risk model to estimate the economic loss in the scenarios of events with different frequency. A method is used to estimate the flooding area in the east river basin, using the digital elevation model (DEM), GIS, and hydrology analysis. The calculation is performed in the following steps: First, the discharge and flood stage of different flood frequencies at hydrology stations are computed with flood time series; then the result is interpolated by GIS spatial analysis module to simulate a flood surface layer; Finally by overlying this layer with the DEM data of the whole research region the flooding area is identified. Since the East River is dammed and the flow is partly controlled by several reservoirs, the flooding area has been greatly reduced. The model also is used to estimate the flooding area in the case of reservoir control. The discharge data from the hydrology stations are readjusted according to historical documents and a flooding area is calculated for the case of reservoir control. The effect of these reservoirs is then estimated by compare the two flood areas for with and without reservoirs. Some sediment problems that alter the fluvial process like sediment mining also are discussed with this model.

Keywords: Flooding risk, GIS, Digital elevation model, Flooding area