北京城市土地利用/覆盖变化及其对雨洪调节服务的影响

深入认识城市土地利用/覆盖变化对雨洪调节服务的影响对于提升城市生态系统服务和雨洪管理具有重要意义。基于多期Landsat遥感影像,利用混合像元分解与人工目视解译集成的方法提取了北京市1991—2014年的土地利用/覆盖数据,模拟评估了不同降雨情景下的地表产流与雨洪调节服务,并分析了城市建成区的土地利用/覆盖变化对雨洪调节服务的影响。结果表明:1991—2014年,北京城市用地面积增长了1096.53 km~2,建成区内不透水面比例上升了9.83%。城市建成区雨洪调节服务总体呈下降趋势,1a、10a、25a和100a一遇降雨情景下平均地表径流调节率分别下降了5.37%、2.40%、1.75%和1.04%,一定程度上加剧了城市的雨洪产流风险。同时,城市新扩张区的土地利用/覆盖变化对雨洪调节服务的影响较老城区更强,贡献度超过84%。建议未来城市新区发展应合理配置不透水地表和绿地空间以提升城市雨洪调节服务。

Urban land use/cover change and its impact on urban flood regulation ecosystem service in Beijing

Understanding the impact of land use/cover change on urban flood regulation ecosystem service (UFRES) is important for improving the urban ecosystem services and urban stormwater management. In this study, Landsat images and hybrid classification approach (including linear spectral unmixing and artificial visual interpretation) were applied to extract urban land use/cover data of Beijing from 1991 to 2014. Then, urban surface runoff and UFRES under different rainfall returning periods were simulated and evaluated in built-up areas, respectively. And we further analyzed the impact of land use/cover change on UFRES. The results indicated that the total area of built-up land increased by 1096.53 km² from 1991 to 2014 in Beijing. Meanwhile, urban impervious surface area (ISA) fraction increased by 9.83%. The UFRES showed a decreased trend with a decrease of runoff reduction efficiency by 5.37%, 2.40%, 1.75% and 1.04% under 1a, 10a, 25a and 100a rainfall returning periods, which increased urban flood risk in a certain extent. Comparing with the old urban area, the land cover change had more significant impact on UFRES in the new expansion urban area, and its contribution ratio is higher than 84%. We suggest the fraction of urban ISA and green space(GS) should be designed properly in the future urban planning to improve UFRES.