Analysis of impacts of polders on flood processes in Qinhuai River Basin, China, using the HEC-RAS model

Huaizhi Wang,Liu Ye,Yu Yuan,Yuqin Gao,Zhenxing Zhang

doi:10.2166/ws.2018.008

Abstract

Abstract Flood control with polders is prevalent in East China. Their impact on flood processes is critically important for flood control, but has not been well documented. The Qinhuai River Basin was selected as the study area. A Hydrologic Engineering Center – River Analysis System (HEC-RAS) hydraulic model was developed to simulate and predict storm flood processes and the associated impact of polders. The study shows that the HEC-RAS model is capable of simulating the impact of polders on flood processes in the Qinhuai River Basin. The polders increased the water level outside of the polders. The polders in upstream watersheds have a greater impact on the water level than polders close to basin outlets when individually distributed. The maximum water level at Dongshan section shows an increasing trend for different sized flood with the increasing number of polders in the basin, and a linear increasing trend associated with urbanization. The smaller the flood scale is, the greater the maximum water level changes.

Highlights

The hydrological effects of urbanization have been receiving increasing attention
The Hydrologic Engineering Center – River Analysis System (HEC-RAS) model developed for this study is based on the cross sections and embankment data in the middle and lower reaches of Qinhuai River
The hydraulic calculation sketch and the HEC-RAS model scheme are shown in Figure 2

Summary

Introduction

The increasing impervious area due to the land use and land cover change caused by urbanization has been found to have a profound impact on urban hydrological process (Liu et al ; Yerramilli ; Zhang & Song ). Increasing impervious area due to urbanization leads to the corresponding increase of the runoff coefficient, resulting in magnified flood volumes and advanced peak flows in flood processes (He et al ; O’Driscoll et al ; Hamel et al ; Schirmer et al ). Hammer ( ) found that hydrological processes would be greatly affected when the impervious percentage of a drainage. Zhou et al ( ) analyzed the influence of urbanization on the hydrological processes in the Yangtze River Delta region, and pointed out that the surface runoff and baseflow respond strongly to urbanization (Zhou et al )

Methods

Results

Conclusion