滇池流域不透水表面动态模拟及其非点源污染风险评价

Dynamic Simulation of Impervious Surface Expansion and Its Risk Assessment on Non-point Source Pollution in Dianchi Lake Basin

利用混合模型综合模拟不透水表面的时空演化规律及其水环境效应是定量探索湖滨型城市可持续发展模式的有效途径。以滇池流域为研究区域,借助遥感与GIS技术探索2000—2016年城市化过程中不透水表面的时空演变特征及其扩张规律,并采用分区元胞自动机模型对2021年和2031年不透水表面的分布进行模拟与预测。进而在子流域和水文响应单元的尺度上计算2000—2031年不透水表面的覆盖率(ISC),对滇池流域历史和未来的水环境城市非点源污染风险进行评价。结果表明:(1)滇池流域不透水表面的扩张具有以滇池湖体为中心向外辐射的显著特征,不透水表面面积增加了286.28 km 2,增长速率为17.9 km 2/年。2006—2009年增长最快为38.8 km 2/年,其覆盖率从2000年的10.16%增加到2016年的20.64%;(2)相比较不分区元胞自动机模型,分区元胞自动机模型在模拟用地变化时的精度有显著提升(Kappa系数提高超过16%,总体精度提高超过26%),可以借以模拟未来不透水表面的扩张情景;(3)子流域和水文响应单元两种尺度下的不透水表面覆盖率都逐年升高,城市非点源污染风险也逐年增大,若不加以重视,风险将会进一步增加。研究结果可为调整土地利用结构、协调城镇建设与水环境保护提供科学依据。

The rapid urbanization of lakeside cities not only results a massive expansion of impervious surface,but also makes a significant influence on water environment.It is an effective way to quantitatively explore the sustainable development of lakeside cities to simulate the spatiotemporal evolution pattern of impervious surface and its water environment effect by using hybrid models.Therefore,taking the Dianchi Lake Basin as the study area,we used remote sensing and GIS technology to analyze the temporal-spatial expansion characteristics of impervious surface from 2000 to 2016 caused by urbanization,and simulated and predicted the distribution of impervious surface in the future of 2021 and 2031 by using the partitioned cellular automata model.Then,the coverage of the impervious surface(ISC)from 2000 to 2031 was calculated on the sub-basin scale and the hydrological response units scale,as well as their temporal-spatial characteristics were analyzed.Finally,the historical and future non-point source pollution risk of Dianchi Lake Basin water environment was evaluated based on the relationship between ISC and water quality.The results show that:(1)the expansion of the impervious surface of the Dianchi Lake Basin is characterized by outward radiation from the Dianchi Lake;the impervious surface area has increased by 286.28 km 2,the annual growth rate is 17.9 km 2,and the fastest annual growth rate in 2006—2009 is 38.8 km 2,its coverage increased from 10.16%in 2000 to 20.64%in 2016;(2)compared to non-partitioned CA model,the partitioned CA model can significantly improve the accuracy of land use changes simulation(where Kappa increases over 16%,and total accuracy increases over 26%),which can be used to simulate the expansion of the impervious surface in the future;(3)the impervious surface coverage both in sub-basins and hydrological response unit has been increasing year by year,and the risk of urban non-point source pollution also increases year by year;if attention does no be paid to the risk,the risk will be more severe in future.These research results can provide the scientific bases for adjusting land use structure and coordinating urban construction as well as water environment protection.