Impact of Human Activities on Recent Changes in Sediment Discharge of the Upper Yangtze River
Online published: 2010-01-25
The upper Yangtze River is the main sediment source of the Yangtze River basin and its sediment yield is closely related with its ecological environment. In recent decades, as human activities intensified strongly, sediment yield in the upper Yangtze River underwent profound changes. Using annual runoff-sediment records in the period of 1956-2007, this paper made a quantitative analysis of characteristics and causes of changes in sediment discharge of main stream and tributaries of the upper Yangtze River in different periods based on double mass curves and empirical models. Our findings are: 1. The relationship between runoff and sediment load of the main stream and tributaries of the upper Yangtze River had obvious phase characteristics, which reflected the impacts of different kinds and intensities of human activities on fluvial sediment yield and transport. The sediment discharge of the upper Yangtze River in 1994-2002 reduced 143 million tons per year and the contribution from human activities accounted for 91.2%. The main decrease was from the Jialing River. The sediment load in 2003-2007 was lowered by 450 million tons per year, of which 14.1% was induced by the reduction of runoff, 39.8% by sustaining human activities appearing in the earlier period, and 46.2% by sediment trapping in the Three Gorges Reservoir and by the decrease of sediment load in the Jinsha River. 2. The sediment discharge of the Jinsha River in the period of 1983-2000 increased by 48 million tons per year, of which 74.7% was associated with human activities, mainly construction of projects. In the period of 2001-2007, the annual sediment load of the Jinsha River was reduced by 118.3 million tons per year, all due to human activities, including various types of reservoirs among which Ertan Reservoir was the biggest one, soil and water conservation practices and decrease of sediment yield from construction projects. 3. The sediment load of the Jaling River decreased by 82.7 million tons per year in 1985-1993, of which 81.4% was related to human activities, such as the changes in rural socio-economic factors and construction of reservoirs. The reduction of sediment load reached 128.5 million tons per year in the period of 1994-2007, of which the decrease of natural runoff accounted for 29.6%, the sustaining human activities appearing in the earlier period for 42.1%, the newly-built reservoirs, such as Baozhusi reservoir, and soil and water conservation project for 23.4%, and human-induced runoff reduction for 4.9%.
DU Jun1,2, SHI Changxing1, ZHANG Shouhong1,2, ZHANG Luan1,2 . Impact of Human Activities on Recent Changes in Sediment Discharge of the Upper Yangtze River[J]. PROGRESS IN GEOGRAPHY, 2010 , 29(1) : 15 -22 . DOI: 10.11820/dlkxjz.2010.01.003
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