Abstract
AbstractThe magnitude of anthropogenic influence, especially dam regulation, on hydrological system is of scientific and practical value for large river management. As the largest dam in the world by far, Three Gorges Dam (TGD) is expected to be a strong evidence on dam impacts on downstream hydrological regime. In this study, statistical methods are performed on the pre‐ and post‐TGD daily hydrological data at Yichang, Hankou, and Datong stations to detect the daily, monthly, yearly, and spatial fluctuations in river hydrology along the Yangtze River during the period of 2000–2013. It is found that TGD makes a significant hydrological variation along the Yangtze River following the dam operation since 2003. Specifically, the daily discharge and water level are gathered to normal event ranges with less extreme events than before 2003. Both maximum and minimum daily water levels at the study stations have decreased due to TGD‐induced riverbed incision. The operation of TGD shifts the maximum monthly discharge and water level from August to July at Yichang station. The significance of TGD effect on discharge and water level relationship presents spatial variation. The rating curves at upstream reach experience the most significant effects with a substantial upward shift, while those at lower reach only suggest slight modification. Of the potential drivers considered in this study, dam regulation is responsible for the changes in downstream river hydrology. Moreover, the tributary and adjoining riparian lakes of the Yangtze River contribute to weaken the effect of TGD on downstream hydrological behavior.
Highlights
The Earth system is experiencing significant changes with response to anthropologic activities
Of the potential drivers considered in this study, dam regulation is responsible for the changes in downstream river hydrology
Since 14 years of information are too short to do hydrological forecasting, this study focuses on the systematic comparison of river flow and water level between predam and postdam periods
Summary
The Earth system is experiencing significant changes with response to anthropologic activities. As the main component of Earth system, rivers around the world are subjected to the regulation of 45,000 large dams since the 1930s [World Commission on Dams, 2000]. The research of dam-induced hydrological variation is of vital importance to study the influence of human activities on the Earth system [Postel et al, 1996; Chao, 1995]. Most previous studies focused on the influence of dam on the reach directly below the dam, without considering the basin-wide influences of dam within a river network
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