Response of land accretion of the Yellow River delta to global climate change and human activity

摘要

In the past 50 years, influenced by global climate change, the Eastern Asian summer monsoon intensity (SMI) changed significantly, and that has led to some response in the water cycle system of the Yellow River basin and in the land accretion process of the delta. The variation in annual precipitation is synchronic with that in SMI. From 1950 to 1970, annual air temperature showed a slight decrease with large fluctuations. Since 1970, a significant increasing trend can be seen. Climate change may result in a change in sediment flux into the sea, and therefore in a change in the rate of land accretion of delta (R_(1a)). The annual R_(1a) and sediment flux into the sea showed an increasing trend from 1952 to 1964, but a decreasing trend after 1964, which is similar to that in the SMI. Human activity such as soil conservation measures and water division also has some effect on land accretion of the delta. A multiple regression analysis indicates that the R_(a1) decreased with decrease in summer monsoon index (SMI), increase in annual temperature (T), the increase in the area of water and soil conservation measures (A_(tfg)) and an increase in water diversion (Q_(w,div)). The contribution of the variations in the variables to the variation in R_(1a) was estimated as 34.94%, 3.80%, 53.82% and 7.44%, respectively. The contribution of the two climate factors totals 38.7%, indicating that the influence of global climate change on the variation in land accretion of Yellow River delta is significant.