Correlation analysis of precipitation and River Flow with the injection and discharge of The Three Gorges Dam and Reservoir

Abstract

The Yangtze River has been the primary support of the resources and transportation of China. Its basin covers an area of 1.8 million square kilometers. The Three Gorges Dam and Reservoir on the Yangtze River is one of the world's largest dams. After the dam construction in 1997, the reservoir started injecting the reservoir to a size of over 600 km2. The influence caused by the dam and reservoir on the river system has been overwhelming and destructive. The possible influence of this vast water body and the operation to maintain this waterbody's size and water level on the river system is significant and ominous. In order to study the relationship between the dam construction and the change in regional precipitation, river discharge, and reservoir injection and discharge, this research used a wavelet and coherence analysis by synthesizing the data of dam injection (1998-2018) and discharge (2003-2018), precipitation from ground stations along the Yangtze River (1952-2020), and river discharge raster maps (1998-2018) to study the temporal correlation and phase coherence among these datasets. The analyses show a high coherence between dam operation and river discharge rates and a minor seasonal coherence between dam operation and precipitation, and a change in precipitation pattern after completion of the dam and reservoir.