Influence of Unsteady Flow Induced by a Large-Scale Hydropower Station on the Water Level Fluctuation of Multi-Approach Channels: A Case Study of the Three Gorges Project, China

Zhiyong Wan,Jianfeng An,Yipeng Liao,Yun Li,Bo Dong,Xiaogang Wang

doi:10.3390/w12102922

Abstract

Unsteady flow induced by hydropower stations exerts a significant impact on the water level in multi-approach channels, which directly threatens the safe passage of ships. In this study, a one-dimensional and a two-dimensional hydrodynamic model are adopted to simulate the water level fluctuations at the entrance of multi-approach channels and the lower lock head of a ship lift with consideration of initial water surface elevation, base flow, flow amplitude, regulation time, and locations of hydropower stations, unfavorable conditions are successfully identified; and the fluctuations at the approach channel entrance and the lower lock head of a ship lift under single-peak and double-peak regulating mode are analyzed considering the flow regulating of the Gezhouba Hydropower Station (GHS), thus, the water level oscillation process in the multi-approach channels is presented. Results show that the largest wave amplitude in the multi-approach channels manifests under unfavorable conditions including lower initial water surface elevation, smaller base flow, larger flow variation, and shorter regulation time; and water level fluctuation in the multi-approach channel is primarily induced by flow amplitude and net flow between the Three Gorges Hydropower Station (TGHS) and the GHS, with consideration of the counter-regulation process of the GHS. This research contributes to providing a reference for a similar large-scale cascade hydropower station regarding regulation and control of navigation conditions.

Highlights

Inland waterways are a crucial part of the domestic transportation network in many countries, such as Europe, the United States, and China [1,2,3,4]
Considering the unsteady flow of the downstream approach channel of the Three Gorges Project (TGP) related to the complex variables such as initial water surface elevation, base flow, flow amplitude, regulation time of hydropower station, and locations of units, in this paper, we aim to investigate the influence of these factors on water level fluctuation in multi-approach channel and to determine the adverse case as a reference for navigation management
Navigation conditions are investigated in many cases according to engineering background, the water level fluctuations in the multi-approach channel fail to be revealed in the context of the broader scientific literature regarding unsteady flow induced by hydropower station

Summary

Introduction

Inland waterways are a crucial part of the domestic transportation network in many countries, such as Europe, the United States, and China [1,2,3,4]. Unsteady flow in the locks approach channel [5,6] is the ubiquitous flow in the shallow waterway, which can generate a considerable influence on downstream navigation, water supply, and sediment transport [7,8]. Water 2020, 12, 2922 locks is prevalant in China, and the unsteady hydrodynamics problem of the common approach channel of multi-line locks is becoming increasingly complicated and varied among actual engineering situations. The water depth in an approach channel is insufficient if the water level fluctuates greatly, which can scrape the bottom of a ship [11], or can break the ship’s cables because of an excessive mooring force, such as the No 2 and No 3 approach channels at the Gezhouba shipping lock, in China. Unsteady flow navigation conditions in an approach channel drastically impact the functional efficiency and safety of any given multi-line lock

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