Impacts of eco-restoration on suspended sediment load in the upper Yangtze River of China

摘要

Vegetation coverage is of great importance to the ecosystem and plays a key role for soil conservation, runoff and sediment yields. Long-term gauging data indicate that eco-programs in the upper Yangtze basin launched since 1989 have increased vegetation coverage through massive afforestation and soil-water conservation measures. The accumulated planting area of 5.3 million hectares has increased catchment forest coverage from 11% in 1978, to 34% in 2010. The mean annual sediment load of 2.78×10~8 t since 1989 is evidently less than that of 5.23×10~8 t before 1989 (a 47% reduction). Comparing the vegetation coverage situation and the sediment regime during 1999-2002 to those of 1984-1998, shows that the riverine suspended sediment load decreased 1.10% per 1% increase in forest coverage. Since 2003, the sediment load has sharply declined due to rapid construction of reservoirs in the upper reaches.