The Yellow River was once the world's largest carrier of fluvial sediment, its annual sediment load peaked at about 1.6 Gt in the middle of the last century. However, its sediment load has decreased by approximately 90% over the past 60 years. The current input of sediment from the Loess Plateau is less than one quarter of what it was before 1980.The current sediment export to the ocean at Lijin station is now only 10.7% of the 1950s’ level. The decline in sediment load is due to changes in water discharge and sediment concentration, which are both influenced by regional climate change and human activities. Scientists from Research Center for Eco-Environmental Sciences of Chinese Academy of Sciences use an attribution approach to analyse 60 years of runoff and sediment load observations from the traverse of the Yellow River over China's Loess Plateau - the source of nearly 90% of its sediment load. They found that landscape engineering, terracing, and the construction of check dams and reservoirs, were the main factors reducing sediment load during the 1950s to 1990s, but this century large-scale vegetation restoration projects have also reduced soil erosion at source. This latter approach will become more important as dams and reservoirs gradually lose their ability to trap sediment. Thus, maintaining a healthy and sustainable vegetated ecosystem is the key to effective soil conservation. Their results are a warning to other areas where deforestation and other land-use changes are exposing vulnerable soils to erosion; and a reminder to those responsible for other major rivers of the world that an integrated water and sediment regulatory strategy is necessary for soil conservation and sediment management. This work was funded by the National Natural Science Foundation of China and the Chinese Academy of Sciences. This research was published in Nature Geoscience under the title “Reduced sediment transport in the Yellow River due to anthropogenic changes” (http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2602.html). State Key Laboratory of Urban and Regional Ecology December 1, 2015 |
