基于SWAT和GIS的洱海流域土地利用变化对径流影响的研究

利用DEM、土地利用、土壤、气象等时空数据并结合GIS和RS技术,建立洱海流域SWAT模型,分析了2000年和2010年不同土地利用情景对径流的影响,其结果为洱海流域土地利用变化引起径流的变化率为2.46%。以《云南省土地利用总体规划大纲(2006—2020)》为依据,结合洱海流域土地利用分布的实际情况,设置3种土地利用情景,研究不同土地利用情景对径流的影响。结果表明情景1中,66.06 km²的耕地转林地和89.16 km²的耕地转草地,模拟的年均径流值增加75.73 mm;情景2中,100.13 km²的裸地和105.74 km²的草地转为耕地,年均径流增加39.89 mm;情景3中,138.72 km²的草地和292.86 km²林地转耕地,年均径流减少20.36 mm。模拟表明在坡度15°以上,洱海流域森林和草地面积的增加将会增加径流量;在坡度15°以下,耕地的增加会一定程度上减少径流量。研究成果为洱海流域水资源空间合理调配提供参考依据。

Response of Runoff to Land Use Change in Erhai Basin Based on SWAT and GIS

DEM,land use,soil,weather and other spatiotemporal data are combined with GIS,RS technology to build the SWAT (Soil and Water Assessment Tool)model for Erhai basin.The influence of land use change on runoff in 2000 and 2010 is analyzed and it is concluded that the rate of runoff change caused by land use change is 2.46%in Erhai basin.According to Overall Planning Framework ofLand Use in Yunnan(2006-2020)and in line with land use distribution in Erhai basin,three land-use scenarios are set up.Simulation results show that in scenario 1 (66.06 km2 farmland are changed into forestland and 89.16 km2 farmland are changed into grassland),the simula-ted annual runoff increases by 75.73mm;while in scenario 2 (100.13 km2 bare land and 105.74 km2 grassland are changed into farmland),the annual runoff increases by 39.89mm;and in scenario 3 (138.72 km2 grassland and 292.86 km2 forestland are changed into farmland),the annual runoff decreases by 20.36mm.We also conclude that when the slope gradient is larger than 15°,increases in forestland and grassland will induce runoff increase,whereas when slope gradient is smaller than 15°,increase in farmland will reduce runoff to some extent.