长沙地区城市内涝风险预警指标研究

Study of Early Warning Indicator of Urban Waterlogging Risk in Changsha Area

摘要: 根据2000~2021年长沙城区的年降水量、月降水量、大雨、暴雨日数等气象资料研究主城区近20年来降雨的变化规律为：年平均降雨量为1388.5 mm，降水分布不均匀，全年降水主要集中在4~7月，暴雨日日数和降雨强度呈现逐年增加的趋势，城区强降水多为短历时强降水，强度大、局地性强；分析2010年以来的16次城市内涝过程，发现内涝发生时大部分个例的主要降雨量集中在1~3时内且1小时、2小时降雨量大，只要少数个例在3小时后还有较强的降水，一般情况下3~6小时最大累积降水量并无明显变化，内涝时大部分个例的1小时降雨量超过20 mm、3小时累积雨量超过50毫米；以区为单位统计2007年以来长沙城区所有自动气象站1小时雨量数据的总样本数、降雨样本数、最大值、0.01%、0.05%、0.1%分位等数据，确定城市内涝风险预警指标为：黄色、橙色、红色三个级别的1小时降雨量标准设定为30毫米、50毫米、70毫米；3小时降雨量标准设定为50毫米、80毫米、110毫米。

Abstract: According to the annual precipitation, monthly precipitation, heavy rain days, rainstorm days and other meteorological data of Changsha urban area from 2000 to 2021, the variation law of rainfall in the main urban area in the past 20 years is studied as follows. The annual average rainfall is 1388.5 millimeter, and the rainfall distribution is uneven. The annual rainfall is mainly concentrated from April to July. The number of rainstorm days and rainfall intensity show a trend of increasing year by year. The heavy rainfall in the urban area is mainly short-term heavy rainfall with high intensity and strong localization. By analyzing the 16 Urban Waterlogging processes since 2010, it is found that the main rainfall of most cases is concentrated in 1~3 hours and the rainfall in 1 hour and 2 hours is large. Only a few cases have strong rainfall after 3 hours. Generally, the maximum accumu-lated rainfall in 3~6 hours does not change significantly. When the waterlogging occurred, the rainfall in most cases exceeded 20 mm in one hour and the accumulated rainfall in three hours exceeded 50 mm. The total sample number, rainfall sample number, maximum value, 0.01%, 0.05%, 0.1% percentile and other data of 1-hour rainfall data of all automatic weather stations in Changsha City since 2007 are counted in the district as a unit, and the urban waterlogging risk early warning indicator is determined as follows: the 1-hour rainfall standard of yellow, orange and red alert is setted as 30, 50 and 70 millimeter; the 3-hour rainfall standard is setted as 50, 80 and 110 millimeter.