土地利用/土地覆被变化对大盈江流域径流的影响

为揭示大盈江流域土地利用/土地覆被变化对径流变化的影响,基于SWAT(Soil and Water Assessment Tool)模型,通过设置不同情景,定量分析了土地利用类型变化对流域内径流的影响。结果显示:(1)SWAT模型在大盈江流域径流模拟中具有较好的适用性,率定期的模型参数R2、Ens分别达到0.68、066,验证期的模型参数R2、Ens分别达到0.69、0.67;(2)大盈江流域月均径流量与土地利用类型关系密切:把农业用地变成林地或者草地,径流量均会减少,把林地变成草地径流量则会增加,农、林、草3种土地利用类型中产流由强到弱依次为农业用地、草地、林地。(3)2006~2015年,大盈江流域土地利用类型变化主要为农业用地和林地转化为草地,这种转变导致流域的月均径流量略有增加,增加的径流量主要是由林地转化为草地所致,且林地转化为草地引起的径流增加量强于农业用地转化为草地引起的径流减少量。

EFFECTS OF LAND USE AND LAND COVER CHANGE ON THE RUNOFF IN DAYING RIVER BASIN

Based on SWAT model and quantitatively analyses,the impact of land use and land cover change(LUCC)on watershed runoff in different scenarios were studied to reveal the influence of LUCC on watershed runoff variation.Results were as follows:(1)SWAT model performs well in simulating Daying River basin runoff.The model parameters R 2 and Ens were 0.68 and 0.69 respectively in parameter calibration period,and 0.66 and 0.67 respectively in model verification period.(2)the average monthly runoff in the Daying River basin is closely related to the land use type:the conversion of farmland into woodland or grassland will decrease watershed runoff,however,the conversion of forest to pasture will increase watershed runoff.The three types of land contributed to the rise of runoff in the order from the largest to the smallest,followed by cultivated land,grassland and forest land.(3)The land use type changed in the Daying River Basin was mainly agricultural and forest land transitioned into grassland between 2006 and 2015.This change resulted in a slight increase in the monthly average runoff of the basin.The increased runoff was mainly caused by the forest land transitioned into grassland,and the increase in runoff caused by the forest land transitions into grassland is stronger than the decrease in runoff caused by the agricultural land transitions into grassland.