黄河中游典型流域土地利用对径流的调控作用

Regulation of Land Use on Runoff in Typical Watersheds of the Middle Reaches of the Yellow River

[目的]深入研究黄河中游不同土地利用对径流变化的调节效应及其阈值,对于山洪防治和流域高质量发展至关重要。[方法]以大理河流域为重点研究区域,分析其近20年来的土地利用变化特征,基于流域月尺度SWAT模型定量分析了土地利用变化对径流年内分配的影响;通过设置4种极端土地利用情况研究了不同土地利用类型对于汛期径流的影响;并通过设置12种不同的土地利用覆盖度情景,揭示了影响流域径流的土地利用的覆盖临界。[结果]大理河流域主要的土地利用方式为耕地、草地和林地,草地和林地对径流有抑制作用,耕地对径流存在促进作用,三者的影响系数分别为-0.125,-0.130,0.122。土地利用对径流的年内分配有一定的调控作用,但当土地利用变化较小时,这种调控作用不明显。土地利用覆盖度存在明显的边际效应,其下临界约为5%,草地的上临界为95%,林地的上临界为91%。[结论]由于流域内实际的植被条件较差,林草覆盖度仍处于较低水平,因此修复植被和适当地退耕、退草还林仍能对该流域的水土保持工作和防洪建设起到促进作用。

[Objective]The aim of this study is to examine the regulatory effects and thresholds of different land uses on runoff variations in the middle reaches of the Yellow River,which is crucial for flood control and the high-quality development of the watershed.[Methods]Focusing specifically on the Dali River Basin,the characteristics of land use changes over the past 20 years were analyzed,and the impact of these changes on the annual distribution of runoff was quantitatively assessed by using a monthly scale SWAT model of the basin.Four extreme land use scenarios were set to study the impact of different land use types on flood season runoff.Additionally,12 different land use coverage scenarios were used to determine the critical coverage of land use that affected watershed runoff.[Results]The predominant land use modes in the Dali River Basin included arable land,grassland,and forest land.Grassland and forestland exhibited an inhibitory effect on runoff,while arable land promoted runoff.The impact coefficients for these land use types were-0.1252,-0.1301,and 0.1223,respectively.Land use had a certain regulatory effect on the annual distribution of runoff.However,this effect was not significant when land use changes were small.[Conclusion]Notably,land use coverage demonstrates a significant marginal effect,with a lower critical value of approximately 5%for grasslands and an upper critical value of 95%,as well as an upper critical value of 91%for forests.These findings can provide valuable insights for soil and water conservation efforts,flood control initiatives,and the high-quality development of the watershed.