Acta Geographica Sinica ›› 2014, Vol. 69 ›› Issue (3): 422-432.doi: 10.11821/dlxb201403013

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Multi-scale variability of water discharge and sediment load in the Pearl River during 1954-2011

WU Chuangshou1,2, YANG Shilun2, HUANG Shichang1, WANG Shanshan1   

  1. 1. Zhejiang Institute of Hydraulics and Estuary, Hangzhou 310020, China;
    2. State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China
  • Received:2013-10-12 Revised:2013-12-20 Online:2014-03-20 Published:2014-03-20
  • Supported by:
    Natuaral ScienceFoundation of China,No.41006502;Minstry of Science and Techology of China,2010CB951202 ;Scienc andTechology Plan in Zhejiang Province,2012F20049;Natuaral Science Foundation of China,LY13E090001

Abstract: This paper is based on hydrological data gathered from Gaoyao (West River), Shijiao (North River) and Boluo (East River) stations in the Pearl River from 1954 to 2011, and the temporal and spatial variations in water discharge and sediment load are analyzed by Mann-Kendall trend test and wavelet analysis. The results are shown as follows. (1) There is no significant trend in water discharge, but a significant decreasing trend in sediment load during 1954-2011 due to impacts of climate change and human activities. Furthermore, there are different trends in different periods. From 1954 to 1983, both water discharge and sediment load show an increasing trend. The contribution rates of climate change and human activities are about 70% and 30%, respectively. From 1984 to 1993, there are undulating phases in water discharge and sediment load (1989 is the changing point), which is mainly resulted from climate change. From 1994 to 2011, both water discharge and sediment load show a decreased trend, and the contribution rates of climate change and human activity to sediment load are about 20% and 80%, respectively. (2) Compared with the data before 2006 when Longtan Dam started operation, the annual average water discharge from 2007 to 2011 decreases by 14%, meanwhile the annual average sediment load decreased by 70% . The contribution rates of reservoirs and soil and water conservation are about 90%. (3) There are apparent decadal cycle periods (DCPs) and annual cycle periods (ACPs) for water discharge and sediment load in different tributaries of the Pearl River, with cycle periods varying among different tributaries. For example in the West River the DCPs of water discharge were mainly 24 yr and 13 yr and ACPs were 4-7 yr, while for sediment loads the DCPs were ~16 yr and 10 yr, and the ACPs were 4-7 yr. In the North River, the significant DCPs of water discharge were about 12 yr, and the ACPs were 2 yr and 8 yr, but the significant DCPs of sediment load were about 13-16 yr, and the ACPs were 4-7 yr and 2-3 yr, respectively. In the East River, both the water discharge and sediment load had 12 yr of DCPs and 2 yr and 6 yr of ACPs. These periodic variations may be related with periodic variations of precipitation in the Pearl River Basin.

Key words: the flux of water discharge and sediment load, Mann-Kendall trend test, Pearl River, wavelet analysis