基于GEE的土地利用/覆被变化对西江流域径流过程影响的定量评估

Quantitative Assessment of Impact of Land Use/Cover Change on Runoff Process in Xijiang River Basin Based on GEE

为分析土地利用/覆被变化对西江流域径流过程的影响,基于VIC水文模型结合武宣水文站多年实测径流数据模拟西江流域水文循环过程,并基于GEE分别提取了1995、2008、2019年西江流域土地利用数据以此驱动VIC模型,定量分析1995~2019年间西江流域土地利用变化对其水文循环过程的影响。结果表明,VIC模型在西江流域适用性良好,月尺度上相关性系数为0.94,相对偏差为9%,纳什效率系数达到了0.85,三大模型评价指标均表现良好。1995~2019年间,西江流域耕地、林地和建设用地的面积占比均有不同程度增加,草地、未利用地面积则不断减小。在此影响下,西江流域多年地表径流深增加了18 mm,蒸散发、涵养指数则分别下降了13 mm、0.006。在年内尺度上,流域径流对土地利用变化的响应在丰水期较枯水期更加敏感。研究结果对西江流域土地利用合理规划和水资源科学管理具有一定现实意义。

This paper simulated the hydrological cycle of the Xijiang River Basin based on the VIC distributed hydrological model combined with the measured runoff data of the Wuxuan Hydrological Station for many years, and extracted the land use data of the Xijiang River Basin in 1995, 2008, and 2019 based on Google Earth Engine(GEE). This drived the VIC model to quantitatively analyze the impact of land use changes on the hydrological cycle in the Xijiang River Basin in 25 years. The results show that the VIC model shows good applicability in the Xijiang River Basin. On a monthly scale, the correlation coefficient is 0.94, the relative deviation BIAS is 9%, the NS efficiency coefficient reaches 0.85, and the three model evaluation indicators perform well. During 1995~2019, the proportion of cultivated land, woodland and construction land in the Xijiang River Basin has increased to varying degrees, while the area of grassland and unused land has been continuously decreasing. The surface runoff depth of the Xijiang River Basin has increased by 18 mm for many years, while the evapotranspiration and conservation index have decreased by 13 mm and 0.006, respectively. In annual scale, the response of runoff to land use variation in wet season is more sensitive to that in dry season. The study has certain practical significance for the rational planning of land use and the scientific management of water resources in the Xijiang River Basin.