Assessing Impacts of Climate Change and Human Activities on Streamflow and Sediment Discharge in the Ganjiang River Basin (1964–2013)

Guo Guo,Zhang Zhang,Bai Bai,Hu Hu,Jin Jin,Mu Mu,Song Song,Chen Chen,Gao Gao,Yu Yu,Liao Liao

doi:10.3390/w11081679

Abstract

National large-scale soil and water conservation controls on the Gangjiang River basin have been documented, but the effect of governance on regional watershed hydrology and how the main driving factors act have not been systematically studied yet. To do this, this study evaluated changing trends and detected transition years for both streamflow and sediment discharge using long-term historical records at seven hydrological stations in the Ganjiang River basin over the past 50 years. The double mass curve (DMC) method was used to quantify the effects of both climate change and human activities on hydrological regime shifts. The results showed that the distributions of precipitation, streamflow, and sediment discharge within a year are extremely uneven and mainly concentrated in the flood season of Jiangxi Province. None of the stations showed significant trends over time for either annual precipitation or streamflow, while the annual sediment discharge at most stations decreased significantly over time. The estimation of sediment discharge via DMC indicated that after the transition years, there were rapid reductions in sediment discharge at all hydrological stations, and the average decline degree of midstream and downstream were much larger than that of upstream. Human activities, especially the increase of vegetation cover and construction of large and medium-sized reservoirs, provided a significantly greater contribution to the reduction of sediment discharge than did precipitation changes. As a case study of river evolution under global change environment, this study could provide scientific basis for the control of soil erosion and the management of water resources in Ganjiang River, as well as for the related research of Poyang Lake and the Yangtze River basin of China.

Highlights

The significant decline of sediment discharge occurred in the 1980s in both Hanlinqiao and Waizhou stations, and the 1990s in Bashang, Xiashan, Ji’an, and Xiajiang stations, and 2002 in
The results demonstrated a significant reduction in annual sediment discharge over time (p > 0.05) at all hydrological stations, but no significant trends for either precipitation or streamflow were found
Significant increasing and decreasing trends were found for both precipitation and streamflow, but only decreasing trends were found for sediment discharge

Summary

Introduction

Climate change could influence regional hydrological cycles by altering precipitation, evapotranspiration, soil moisture, and temperature, and causing changes in river runoff [1,2]. A large number of studies have shown that human activities, such as large-scale vegetation destruction and reconstruction and massive construction of water conservancy facilities (e.g., reservoirs) may lead to major changes in land use patterns, which can greatly change the underlying surface conditions of the basin, thereby producing changes in runoff and sediment processes in a river basin [4,5,6,7]. As global climate warming increases due to human activities, there is increasing concern in the scientific fields of water conservancy engineering, river geomorphology, and land water cycle regarding trends in water movement and sediment deposition, and regarding the contribution that climate change and human activities make to these processes [13,14,15,16]

Methods

Results

Conclusion