1934-2025年黄土高原入黄泥沙变化OA

An objective and accurate assessment of the water-sediment regime of the Yellow River is an important prerequisite for formulating strategies for Yellow River governance and major engineering measures.Based on observed data of runoff,sediment,precipitation,and vege-tation since 1934,this study analyzed the variation characteristics of sediment inflow into the Yellow River from the Loess Plateau,rainfall-sediment yield relationship,sediment concentration during flood seasons,sediment inflow coefficient,and sediment particle size.The results show that the sediment inflow into the Yellow River from the Loess Plateau can be generally divided into three periods since 1934:1934-1969,1970-2007,and 2008-2025.The period 1934-1969 was generally a natural period,during which the impacts of human-induced land surface degradation and conservation offset each other in the last decade.From 1970 to 2007,although sediment inflow decreased by 52%,the water-sediment relationship during flood seasons remained unfavorable,and sediment reduction in most years was characterized as"un-healthy".Since 2008,large numbers of early-built check dams and reservoirs have gradually lost their flood retention and sediment trapping capacity.Meanwhile,vegetation restoration and terrace construction have achieved substantial sediment reduction at the source.As a result,the annual sediment inflow into the Yellow River has decreased to 255 million tons,sediment particles have become finer,flood-season sedi-ment concentration has decreased by 82%,and the incoming sediment coefficient has decreased by 63%,indicating that the Loess Plateau has entered a stage of healthy sediment reduction.Notably,sediment yield rebound has occurred in the upper Malian River and upper Beiluo River in recent years due to declining vegetation coverage.This phenomenon warns that sustained efforts are still required to maintain the hard-won favorable state of healthy sediment reduction in the long term.