Sediment and runoff changes in the Yangtze River basin during past 50 years Qiang Zhang a,b, * , Chong-yu Xu a,c , Stefan Becker d , Tong Jiang a a Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing 210008, China b Department of Geography, University of Giessen, Senckenbergstrasse 1, 35390 Giessen, Germany c Department of Geosciences, University of Oslo, Norway d Department of Geography and Urban Planning, University of Wisconsin-Oshkosh, Oshkosh, WI 54901, USA Received 12 October 2005; received in revised form 22 May 2006; accepted 22 May 2006 Summary Annual runoff and annual suspended sediment loads of hydrological gauging stations along the mainstream of the Yangtze River basin (Pingshan station, Yichang station, Hankou sta- tion and Datong station) and main tributaries (Beipei station in Jialingjiang River, Wulong sta- tion in Wujiang River and Huangzhuang station in Hanjiang River) were analyzed with the help of Mann–Kendall trend analysis and linear regression analysis. Research results indicate that (1) changing patterns of runoff and sediment loads are different in different parts of the Yangtze River basin. No significant trend is detected for annual runoff at all stations at >95% confidence level. Changes of sediment loads, however, demonstrate different pictures in the Yangtze River basin. The sediment loads are in increasing trend in Pingshan station- the most upstream station on the Yangtze River basin (this increasing trend is significant at >95% confidence level after about 1990), but are in decreasing trend at other stations (including stations in the tributaries studied in this paper). This decreasing trend becomes more obvious from Yichang station to Datong station. (2) Water reservoirs exerted more influences on changes of sediment loads than on runoff, which is the main reason for the decreasing trend of sediment loads found in most stations. (3) Influences of water reservoirs on sediment loads are more obvious in the tributaries than in the mainstream of the Yangtze River basin, while in the mainstream the variation pat- terns of sediment loads are determined by multiple factors.  c 2006 Elsevier B.V. All rights reserved. KEYWORDS Sediment load; Runoff; Mann–Kendall trend test; Yangtze river basin Introduction Fluvial geomorphology is sensitive to climatic changes and human disturbance, and these changes alter the dynamic processes of the erosion and deposition of the fluvial system 0022-1694/$ - see front matter  c 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jhydrol.2006.05.036 * Corresponding author. Present address: Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing 210008, China. E-mail address: zhangqiang@nju.org.cn (Q. Zhang). Journal of Hydrology (2006) 331, 511– 523 available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/jhydrol