极端天气影响下城镇洪水水位快速估计与淹没分析

由于城镇化的快速发展和极端天气影响,土地利用与防洪安全的矛盾日益突出,城镇洪涝风险增加。以四川省渠县为研究区域,综合运用历史洪水记录与多年水文观测数据重建洪水水位数据序列,快速估计城镇洪水水位并进行淹没分析。通过分析洪水频率与水位的关系、洪水水位差以及不同位置洪峰相关性,更新渠县沿江主要城镇各重现期洪水水位;结合沿江城镇发展定位和预期人口规模,重新核定防护等级和防洪标准。结果表明:渠县主要城镇的洪水水位较历史水平平均上升40 cm,其中100年一遇、50年一遇和10年一遇洪水水位分别上升至254.75,253.48,250.54 m。根据国家防洪标准,渠县主城区和三汇镇的防洪重现期标准应分别提高至50年一遇和20年一遇,其他沿江城镇和乡村的防洪重现期标准保持为10年一遇。与现行防洪标准相比,提高设防标准可减少农地淹没面积超过30 km²,减少建设用地淹没面积7~8 km²。

Quick Estimation of Urban Flood Levels and Inundation Analysis Under the Impact of Extreme Weather

Due to the rapid development of urbanization and the impact of extreme weather, the conflict between urban land use and flood safety becomes prominent while the flooding risk increases. Taking Quxian of Sichuan Province as the study area, we updated the flood level and conduct inundation risk analysis. Using historical flood records and observation data over the past few decades, we established the flood level dataset and re-estimated the flood level in various recurrence intervals by analyzing the distribution of flood frequency and peak flood levels, and the correlation between flood levels at different locations. It was shown that, as a result of extreme weather, the flood levels of the main counties in Quxian have increased by an average of 40 cm compared with historical flood levels, i,e., those of the once-in-100-year, once-in-50-year, and once-in-10-year have risen to 254.75, 253.48 and 250.54 m, respectively. According to the national flood control standard, the central city of Quxian and Sanhui County should be able to resist flood with recurrence intervals of 50 and 20 years respectively, while other counties along the river remain at 10 years. Compared with the current flood control standard, the updated standards could potentially prevent agricultural and construction land from flooding by more than 30 and 7~8 km² respectively.