Abstract:

The variation trend of sediment and precipitation in Longhe River Watershed which is the centre of the Three Gorges Reservoir area was analyzed according to the measured data in 1963-2010. Pettitt test, accumulative anomaly analysis and double mass curve analysis were employed for the research. The year 1982 was found to be the inflection point of precipitation, and 1982 and 1990 the inflection points of sediment load. The contributions of precipitation and human activity to sediment change during three periods (1963-1981, 1982-1990, 1991-2010) were compared and analyzed. Results reveal that with 1963-1981 as baseline period, precipitation and human activity contribute 29.49% and 60.51% respectively to the sediment change in 1982-1990, and 3.38% and 96.62% respectively in 1991-2010; whereas when 1982-1990 is taken as the baseline period, human activity alone contributes 100% to the sediment decrease in 1991-2010. This research reveals the trend of sediment load change in Longhe River watershed during 1963-2010, and also the contributions of precipitation and human activity. It is of great importance to the soil and water conservation and assessment, and also provides theoretical support to the sharp decline of runoff and sediment discharge in Three Gorges Reservoir Area.

Key words: runoff and sediment relationship, Longhe river watershed, human activities, contribution rate, Three Gorges Reservoir area