Analysis of Sediment Variation in Important Tributaries of the Yellow River in the Sandy and Coarse Sediment Area Based on Detrital Zircons and Hydrological Observations
Objective The significant accumulation of silt constitutes a critical factor contributing to water and sediment disasters in the Yellow River.In re-cent years,the runoff and sediment transport of the Yellow River and its primary tributaries have decreased significantly.Although extensive re-search has been conducted,the multi-temporal and spatial scale characteristics of sediment production and transport remain unclear.Methods This study examines the Huangfu River and Kuye River tributaries in the high coarse sediment area of the Loess Plateau to analyze the multi-temporal and spatial characteristics of sediment production and transport.The analysis integrates modern hydrological observation data and detrital zircon source testing methods from 1960 to 2021.Measured hydrological data are analyzed using statistical test methods,with the Mann-Kendall test employed to evaluate hydrological trends and the accumulation method utilized to identify abrupt change points in water and sediment data.The findings indicated a significant decreasing trend in annual runoff and sediment transport in the Huangfuchuan and Kuye River basins over recent decades.Abrupt change points in the runoff and sediment transport of the Huangfu River occurred in 1978 and 1998,showing a significant decline.In the Kuye River,abrupt change points in runoff occurred in 1979,1997,and 2011.The first two points showed significant decreases,while the last point indicated a significant increase.Abrupt change points in sediment transport for the Kuye River appeared in 1979 and 1997,showing significant decreases.Detrital zircon experiments conducted on modern river sediments and river terrace sediments from sev-eral thousand years ago in the Huangfu River and Kuye River(2020)reveal that sediments are primarily composed of loess and bedrock,with modern river sediments containing a higher contribution rate of loess than terrace sediments.Results and Discussions The findings showed that precipitation and human activities are the primary factors influencing runoff and sediment transport.However,precipitation has not changed significantly in recent decades.Since 1980,human activities have become the dominant factor contributing to reductions in water and sediment,while precipitation plays a secondary role.The sharp decrease in sediment transport and the rel-ative increase in the proportion of loess result from accelerated loess erosion caused by human activities.Simultaneously,exploiting surface wa-ter resources and soil and water conservation measures in the basin reduces runoff,decreasing the sediment transport ratio.Large amounts of slope-eroded loess are deposited in river channels rather than transported to drainage outlets,providing a sediment source for extreme rainstorms.There-fore,ongoing attention to soil and water conservation on the Loess Plateau is essential.Conclusions This study employs modern-scale hydrological observation data and geological sedimentology methods,combined with multi-scale approaches,to provide insights into controlling water and sediment disasters in the Yellow River.Although the application of detrital zircon source methods to reflect sediment transport in rivers remains underexplored,their effectiveness and applicability require further investigation.This study highlights the temporal changes in sediment transport in the Huangfuchuan and Kuye Rivers,key tributaries in the coarse and sandy area of the Yellow River.It proposes further analysis of spatial changes using InSAR,UAV,and other remote sensing technologies.
Yellow Riverrunoffsediment transport capacitydetrital zircon source
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