Flooding simulation and mitigation in an urban catchment of Beijing

摘要

During the last twenty years, the hydrological characteristics of urban catchment have had a great change due to the rapid urbanization, while the storm sewers had comparatively less improvement. As a result, the risk of flooding is increasing in many places. The catchments in city of Beijing are among such typical situations. Meanwhile, in addition to the risk of flooding, the crisis of water shortage in Beijing becomes fairly sharp in recent years because of the large water consumption during the urban development and limited precipitation in nature. Moreover, the ground water has been overused and its quality is deteriorating. Therefore, it is an urgent task to study the risk of flooding and its mitigation by taking the use of storm water into consideration. The MOUSE runoff and pipe flow models are applied in this study. The models are calibrated by an urban catchment, Baiwanzhuang, in Beijing. The conveying ability of storm sewers is verified and the risk of flooding is studied with respect to the selected design storms. The flooding volume is estimated in order to eliminate the potential damage in combination with the use of storm water. On this basis, two flooding mitigation measures, increasing the pervious areas and constructing water detention tanks, are examined individually. The simulation indicates that increasing the rate of pervious areas can not only reduce the risk of flooding but also compensate the groundwater and improve the ecological environment as well. Moreover, when two water storage tanks are fabricated at two sensitive nodes in existing sewer networks, the surface flooding of 10-year storm can be controlled and in turn, this part of water can be kept for other use. It is, therefore, an integrated technique to solve the flooding problems in combination with employing the water resources in a sustainable way.