LUCC及气候变化对澜沧江流域径流的影响

运用SWAT模型,通过设置不同情景,定量分析了澜沧江流域土地利用与土地覆被变化(Land Use and Land Cover Change,LUCC)和气候变化对径流的影响,并结合RCP4.5、RCP8.5两种排放情景对流域未来径流的变化进行预估。结果表明:SWAT模型在澜沧江流域径流模拟中具有很好的适用性,率定期和验证期的模型参数R~2分别达到0.80、0.74,Ens分别达到0.80、0.73;从土地利用变化方面考虑,流域内的农业用地转化为林地或草地,均会导致径流量的减少,而林地转化为草地则会引起径流量的增加,农业用地、林地、草地三者对径流增加贡献顺序为农业用地草地林地,从气候变化方面考虑,流域内的径流量与降雨量成正比,与气温成反比;2006—2015年间澜沧江流域气候变化引起的月均径流减少幅度强于LUCC引起的月均径流增加幅度,径流变化由气候变化主导;在RCP4.5和RCP8.5两种排放情景下,2021—2050年间澜沧江流域的径流均呈增加趋势,这与1971—2015年间流域实测径流的变化趋势相反。

Impacts of LUCC and climate change on runoff in Lancang River Basin

Using the SWAT (Soil and Water Assessment Tools) model, the impacts of LUCC (land use and land cover change) and climate change on runoff in Lancang River Basin were quantitatively analyzed by setting different scenarios. The future runoff changes were predicted with RCP4.5 and RCP8.5 emissions scenarios in Lancang River Basin. The results showed that the SWAT model had good applicability in runoff simulation of Lancang River Basin. The model parameters R² of calibration and validation periods were 0.80 and 0.74, respectively. The model parameters Ens of calibration and validation periods were 0.80 and 0.73, respectively. Considering the land use change, the conversion of farmland into woodland or grassland would reduce basin runoff, but the conversion of woodland into grassland would increase basin runoff. The contribution to basin runoff from big to small was farmland, grassland, and woodland. Regarding climate change, the basin runoff was proportional to rainfall, but inversely proportional to temperature. The reduction of monthly runoff caused by climate change was stronger than the increment caused by LUCC in Lancang River Basin from 2006 to 2015. Therefore, runoff change was dominated by climate change. The runoff in Lancang River Basin in both RCP4.5 and RCP8.5 emissions scenarios would increase from 2021 to 2050, which is contrary to the measured basin runoff from 1971 to 2015.