Impoundment Impact of the Three Gorge Reservoir on the Hydrological Regime in the Lower Han River, China

Luojie Feng,Junhong Zhang,Sujie Chen,Minglong Dai,Tao Huang,Lu Chen,Dongdong Zhang,Dangwei Wang

doi:10.3390/w10111670

Abstract

Reservoir regulation has been playing an increasingly important role in water resources development and its influence on the hydrological processes of downstream tributaries has attracted much attention. The lower Han River is selected as a case study to examine the hydrological and hydraulic influence of the upstream flow regulation of the Three Gorges Reservoir (TGR) in the middle Yangtze River, China. Based on a hydrodynamic model and the observed data, the hydrological processes in the lower Han River were simulated and their changes were analyzed under the impoundment influences of the TGR. The results indicated that there were obviously hydrological changes in the lower Han River after the TGR operation. The decreased stage downstream the TGR during the impounding periods of the TGR resulted in an increase in the stage difference, current speed, hydraulic gradient and the discharge ratio. In addition, the stage difference between the two rivers was decreased during the periods of water compensation from the TGR, which led to the outflow congestion in the lower Han River. The hydrological changes in the lower Han River were the response to the flow regulation of the TGR and the inflow of the two rivers. The variation in the rating curve in the lower Han River mainly resulted from the stage difference between the two rivers during the dispatching periods of the TGR. These results help to explain the hydrological variability under the impounding influence of the TGR for the lower Han River and they can be extended to other river tributaries downstream to the reservoirs.

Highlights

Dam construction around the world has been playing an increasingly important role in water resources development, electricity generation and flood control [1]
In order to evaluate the hydrological and hydraulic changes in the lower Han River after the Three Gorges Reservoir (TGR) operation, a data-driven modeling approach was applied based on the MIKE11 model package
The hydrological processes in 2007 and 2005 that covered flooding and drying events were selected for model calibration and validation respectively

Summary

Introduction

Dam construction around the world has been playing an increasingly important role in water resources development, electricity generation and flood control [1]. Large-scale and dramatic hydrological changes usually occur from upper to lower river basins, which result in significant changes. Water 2018, 10, 1670 in hydrological processes and hydraulic regime in the adjoining tributaries [2]. The hydrodynamic balance is disturbed in the lower tributaries, which does a great harm to the flood control and waterway maintenance [4,5]. Researching on hydrodynamic characteristics in the lower tributaries is of significance for river health [6]. During the past several decades, an increasing number of scholars began to pay attention to the response of water flow to the reservoir impoundment in the tributary sub-basins.

Methods

Results

Discussion

Conclusion