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    砒砂岩区小流域坡面产流产沙对植被-降雨耦合作用的响应规律

    Response of hillslope runoff and sediment yield to vegetation–rainfall coupling in watershed of Pisha Sandstone region

    • 摘要: 为探讨黄土高原砒砂岩区不同降雨类型下不同植被类型的产流产沙特征及驱动因素,本研究以圪坨店小流域为研究区,开展六种植被类型(油松、天然草地、人工草地、沙棘、农地、裸地)产流产沙定位观测,分析不同降雨类型下不同土地利用类型的产流产沙特征,并采用结构方程模型分析降水、土壤、植被生物量、地形等因素对产流产沙的影响。结果表明:1)2019—2023年,累积观测侵蚀性降雨事件42次,可划分为Ⅳ种降雨类型,I类(降雨量最大,I30最大)、II类(降雨历时最短,降雨强度最大)、III类(降雨量、降雨强度、历时均中等)和IV类(降雨历时最长),其中I类降雨下产流产沙量最大;2)不同类型径流小区产流量和泥沙量差异显著(P < 0.01),产流产沙量大小依次为裸地>农田>人工草地>天然草地>灌木>乔木;不同降雨类型下,各植被类型产流量和产沙量有显著差异(P < 0.05),仅油松小区在I类降雨下产流产沙较低;3)不同降雨类型下,影响产流产沙的因素不同,其中,降雨因子在I、III、IV类降雨中影响显著(P < 0.05),土壤因子在II、III、IV类降雨中影响显著(P < 0.05),坡度因子在所有降雨类型均影响显著(P < 0.05),Ⅰ类降雨的产流以降雨因子为主导(P < 0.001),Ⅱ类与Ⅳ类降雨的产流以土壤因子为主导(P < 0.001),各降雨类型下产沙量的主要驱动因素都为产流量。研究结果可为砒砂岩区植被恢复与流域治理提供科学依据。

       

      Abstract: Background The Pisha Sandstone region on the Loess Plateau experiences intense hillslope erosion. Clarifying how vegetation types respond to distinct rainfall patterns is essential for targeted restoration and watershed management. Methods In the Getuodian watershed, we monitored runoff and sediment from standard runoff plots representing six vegetation/land-use types (Chinese pine forest, sea buckthorn shrubland, natural grassland, planted grassland, cropland, and bare land) during the period 2019-2023. We grouped 42 erosive storms into four rainfall patterns using k-means, based on rainfall amount, I30 (maximum 30-min intensity), duration, and rainfall erosivity. We compared responses across patterns and used structural equation modeling—based on principal components of rainfall and soil variables—to identify drivers. Results 1) A total of 42 erosive rainfall events were recorded and classified into four rainfall patterns. Among them, Class I events—characterized by the largest rainfall amount and I30—produced the highest runoff and sediment yield. 2) Runoff and sediment yield differed significantly among plot types (P < 0.01), with the overall order: bare land > cropland > planted grassland > natural grassland > shrubland > forest. Across rainfall patterns, each vegetation type showed significant differences in runoff and sediment yield (P < 0.05); only the Chinese pine plot remained low even under Class I rainfall. 3) The dominant drivers varied by rainfall pattern: rainfall factors were significant in Classes I, III, and IV (P < 0.05); soil factors were significant in Classes II, III, and IV (P < 0.05); and slope was significant across all patterns (P < 0.05). For runoff, Class I events were dominated by rainfall factors (P < 0.001), whereas Classes II and IV were dominated by soil factors (P < 0.001). For sediment yield, runoff volume was the principal driver under all patterns. Conclusions This study demonstrates how vegetation types and rainfall patterns shape runoff and sediment yield in the Pisha sandstone region and identifies the key driving factors, thereby providing a scientific basis for vegetation restoration and watershed management in this area.

       

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