Influence of the Three Gorges Project on the Water Resource Components of Poyang Lake Watershed: Observations from TRMM and GRACE

Xiaobin Cai,Yuxi Wang,Xiaoling Chen,Lian Feng

doi:10.1155/2015/148913

Abstract

The Three Gorges Project (TGP) has received many criticisms about its potential effects on the changes in the downstream ecosystems. Poyang Lake is the largest body of water downstream of the TGP, and it is not immune to these changes. TRMM and GRACE data were introduced in this study to estimate river-lake water exchange, from which the hydrological responses of Poyang Lake could be identified. A significant decreasing trend of the runoff coefficient has been observed since 2003, resulting in 6.02 km3more water discharge from the lake into the Yangtze River than under normal conditions. No significant interannual changes occurred in the water level or local precipitation, and GRACE observations revealed that groundwater discharge appeared to be the most likely compensation for the water loss. A novel approach, namely, the groundwater abnormality index (GAI), was developed to depict the water exchange using GRACE and surface water observations. Lower than normal GAIs were found between 2003 and 2005, reaching a minimum of −29.26 in October 2003, corresponding to ten times of the mean GAI during 2006–2012, clearly indicating a significant water exchange in Poyang Lake Basin from groundwater to surface water after the TGP impoundment.

Highlights

The hydrological conditions of some of the world’s water systems have been disturbed by climate change and/or human activities [1,2,3], leading to numerous social and ecological problems
The monthly mean water level of Poyang Lake fluctuated between 14.47 m and 19.67 m during 2003–2012, with the maximum observed in February 2004 and the minimum in July 2010, respectively
The relationship between annual precipitation (y) and runoff depth (x) of the Poyang Lake drainage can be defined as y = 1.4752x + 1883.2

Summary

Introduction

The hydrological conditions of some of the world’s water systems have been disturbed by climate change and/or human activities [1,2,3], leading to numerous social and ecological problems. A typical example is the Three Gorges Project (TGP) or Three Gorges Dam (TGD) of China, which is constructed in the middle reach of the Yangtze River (see Figure 1(a)). Since the impoundment of the TGP in 2003, the ecosystem of the downstream Yangtze River has been reported to be significantly changed. The operation of the TGP has altered the water and sediment discharges of the downstream Yangtze River in terms of magnitude and temporal distribution [4,5,6]. The unique geographic position and hydrologic conditions of Poyang Lake make it an optimal area to study the downstream influence of the TGP. With hydrological and satellite observations [8], it was reported that 7.86 km of water was lost from Poyang Lake after the impoundment of the TGP in 2003. A decreasing trend has been observed in the inundated area of the lake using long term MODIS observations [9], and this has been further confirmed [10] with higher resolution Landsat TM/ETM+ and hydrological measurements

Results

Discussion

Conclusion