Lake hydrology, water quality and ecology impacts of altered river–lake interactions: advances in research on the middle Yangtze river

Xia Jiang,Xijun Lai,Huichao Dai,Guangchun Lei,Ling Li,Rongrong Wan,Yongjun Lu,Guishan Yang,Qi Zhang,Jianchi Chen

doi:10.2166/nh.2016.003

Abstract

Water and mass exchange between rivers and lakes are key processes that maintain the health of the ecology of river–lake systems. Alteration to river–lake interactions have great impacts on water and mass balances. Naturally connected to the middle Yangtze River are the Poyang Lake and Dongting Lake, which are the largest and the second largest freshwater lakes in China. The operation of the Three Gorges Dam (TGD) in the upper Yangtze River was found to have substantial impacts on the middle Yangtze river–lake system. In the past decade, unusual seasonal dryness was evident in the two lakes. Considerable deviations in lake water quality and wetland ecosystem were also detected. In order to explore and distinguish the causal factors influencing the river–lake system, the Ministry of Sciences and Technology (China) launched a research project in 2012, the National Basic Research Program of China (973 Program) (2012CB417000). This article provides an overview of advances in this research, including the evolution of the river–lake interactions, the impacts of the TGD, and the influences on lake hydrology, water quality, and ecosystem. The 20 papers in this issue deliver part of the research outcomes of this project.

Highlights

The Yangtze River is the largest river in China and the third largest in the world, with an average annual runoff of 9,970 × 108 m3, accounting for about 40% of the total river runoff volume in China
The water and sand transfer properties between the Yangtze River and the Dongting Lake and Poyang Lake are regarded as typical river–lake interactions
The optimal scheduling is to appropriately store water in advance under the premise of guaranteeing the security of flood control; that is, on the basis of regular scheduling, to decrease the discharge of the reservoir system in mid-August and at the end of the storage period to gradually increase discharge to secure lake ecosystem health. This scheduling can basically minimize the adverse effects of the reservoir filling on river–lake interaction in normal years and wet years

Summary

INTRODUCTION

The exchange relationships of water, sediments, dissolved constituents, and energy between rivers and lakes significantly influence the geomorphology, water regime, water. Supported by the National Basic Research Program of China (973 Program) ‘Evolution of river–lake relationship in middle Yangtze River and impacts on water quality and ecology and regulation strategies’ (2012CB417000) (http:// www.yangtze973.ac.cn/), the Chinese Academy of Sciences and Ministry of Water Resources teamed together several research institutes and universities to conduct this research. The 20 papers included in this issue are part of the research outcomes of this project

OVERVIEW OF RESEARCH ADVANCES OF THIS PROJECT

Findings

ABOUT THE PAPERS IN THIS ISSUE