基于SWAT模型的丹江流域土地利用变化对径流影响研究

为定量分析土地利用类型变化对径流的影响,基于SWAT模型,通过分析丹江流域近20年来的土地利用变化,并设置3种不同土地利用情景模式,探究了土地利用类型对流域径流的影响作用。结果表明:SWAT模型率定期和验证期的决定性系数R²和纳什效率系数NS分别为0.8,0.73和0.86,0.78,适用于丹江流域径流模拟。2000—2020年,丹江流域土地利用变化引起的径流变化为-0.18%; 情景1中,把林地、草地全变为耕地的情况下,模拟的年均径流变化率为61.65%,情景2中,把耕地和草地全转换为林地的情况下,模拟的年均径流变化率为-12.69%,情景3中,把耕地和林地全转换为草地的情况下,模拟的年均径流变化率为24.24%。耕地对径流深度的影响系数为0.26 mm/hm²,林地对径流深度的影响系数为-13.35 mm/hm²,草地对径流深的影响系数为-0.01 mm/hm²。由此得出,耕地对产流起促进作用,草地和林地对产流起抑制作用。为维护丹江流域生态环境,增强丹江流域径流供给,应科学开发耕地资源。

Study on the Impact of Land Use Change on Runoff in Danjiang Watershed Based on SWAT Model

In order to quantitatively analyze the impact of land use type changes on runoff, based on the SWAT model, the land use changes were analyzed in the Danjiang River Basin in the past 20 years, and three different land use scenarios were set up to explore the impact of different land use types on runoff. The results show that the decisive coefficient R² and the Nash efficiency coefficient NS of the SWAT model were 0.8, 0.73 and 0.86, 0.78 in the regular and validation periods, respectively, which were suitable for the runoff simulation in the Danjiang River Basin; from 2000 to 2020, the runoff change caused by land use change in the Danjiang River Basin was -0.18%; in scenario 1, when the forest land and grassland are all turned into cultivated land, the simulated average annual runoff change rate is 61.65%; in scenario 2, when all cultivated land and grassland are converted into forest land, the simulated average annual runoff change rate is -12.69%; in scenario 3, when all cultivated land and forest land are converted into grassland, the simulated annual average runoff change rate is 24.24%; The influence coefficient of cultivated land on runoff depth was 0.26 mm/hm², the influence coefficient of forest land on runoff depth was -13.35 mm/hm², and the influence coefficient of grassland on runoff depth was -0.01 mm/hm². It can be concluded that cultivated land promotes runoff, while grassland and forest land inhibit runoff. In order to maintain the ecological environment of the Danjiang River Basin and enhance the runoff supply of the Danjiang River Basin, cultivated land resources should be developed scientifically.