祁连山阿咪东索小流域典型水文年草地和灌丛坡面产流特征研究OA

The runoff generation process on slopes in the permafrost region of alpine areas is jointly regulated by precipitation,freeze-thaw cycles,and the underlying surface structure,exhibiting significant phase-specific and spatial heterogeneity.This study focused on the grassland and shrub slopes in the Amidongsuo sub-watershed of the Babao River Basin in the Qilian Mountains,and based on the monitoring data from September 2023 to Au-gust 2024,explored the changing characteristics of runoff generation patterns on alpine slopes during the freeze-thaw alternation under the background of a"normal and slightly abundant year".The results show that:(1)Fre-quency analysis of the 41-year precipitation sequence at the Qilian Meteorological Station indicates that the ob-served annual precipitation is 467.73 mm,with a recurrence period of approximately 4.2 years,which is a com-mon hydrological event.(2)There are significant differences in the runoff generation components between the two slopes.The shrub slope is dominated by interflow(accounting for 96.62%of the total runoff),while the grassland slope is dominated by surface runoff(accounting for 53.4%of the total runoff);the total runoff volume of the shrub slope is 38.13 times that of the grassland slope.(3)Runoff generation is restricted during the freezing period,and surface runoff rapidly increases during the thawing period,with the contribution of stratified runoff changing in phases as the freeze-thaw process progresses.(4)Slope runoff generation can be classified into three typical patterns:overland surface runoff(triggered by short-term heavy rain,typical event on June 16-17,2024),shallow saturated surface runoff(caused by continuous precipitation in the early stage,even weak rain can gener-ate runoff,typical event on August 29-30,2024),and interflow.The discrimination basis comes from the cou-pling characteristics of rainfall intensity,soil moisture/temperature time series,and runoff response.The study re-veals the slope runoff generation patterns jointly controlled by"precipitation-freeze-thaw-underlying surface type",which can provide observational basis for the simulation of alpine slope hydrological processes and the as-sessment of water source conservation in the Qilian Mountains;at the same time,it points out that the conclu-sions are primarily applicable to the background of a"normal and slightly abundant year",and further verifica-tion and promotion with multi-year sequences and extreme year-type data are still needed.