Attribution of climate change, vegetation restoration, and engineering measures to the reduction of suspended sediment in the Kejie catchment, southwest China

Hydrology and Earth System Sciences

X.Ma¹  J. T.Li¹  X. X.Lu¹  M.van Noordwijk¹  J. C.Xu¹ 

DOI  :  10.5194/hess-18-1979-2014

学科分类：地球科学(综合)

来源: Copernicus Publications

【 摘 要 】

Suspended sediment transport in rivers is controlled by terrain, climate, andhuman activities. These variables affect hillslope and riverbank erosion atthe source, transport velocities and sedimentation opportunities in the riverchannel, and trapping in reservoirs. The relative importance of those factorsvaries by context, but the specific attribution to sediment transfer isimportant for policymaking, and has wide implications on watershedmanagement. In our research, we analyzed data from the Kejie watershed in theupper Salween River (Yunnan Province, China), where a combination of landcover change (reforestation, as well as soil and water conservation measures)and river channel engineering (sand mining and check dam construction)interact with a changing climate. Records (1971–2010) of river flow andsuspended sediment loads were combined with five land-use maps from 1974,1991, 2001, 2006 and 2009. Average annual sediment yield decreased from13.7 t ha⁻¹ yr⁻¹ to 8.3 t ha⁻¹ yr⁻¹ between theperiod 1971–1985 and the period 1986–2010. A distributed hydrological model(Soil and Water Assessment Tools, SWAT) was set up to simulate the sedimentsourcing and transport process. By recombining land-use and climate data forthe two periods in model scenarios, the contribution of these two factorscould be assessed with engineering effects derived from residual measuredminus modeled transport. Overall, we found that 47.8% of the decreasewas due to land-use and land cover change, 19.8% to climate change,resulting in a milder rainfall regime, 26.1% to watershed engineeringmeasures, and the remaining 6.3% was due to the simulation percent bias.Moreover, mean annual suspended sediment yield decreased drastically with theincrease of forest cover, making diverse forest cover one of the mosteffective ecosystems to control erosion. For consideration of stakeholdersand policymakers, we also discuss at length the modeling uncertainty andimplications for future soil and water conservation initiatives in China.

【 授权许可】

Unknown