Coping Strategies Of Urban Drought And Flood Risk In The Context Of Climate Change

With the rapid development of urbanization,the city's water security and water environment have been seriously threatened.Many cities have problems such as drought and flood.At the same time,in the context of global warming,the atmospheric water cycle becomes more active,and frequent regional extreme precipitation and extreme drought events lead to serious pressures for cities.With the development of sponge city,in recent years,our country has developed rapidly in the field of stormwater management,and has produced many excellent research achievements in theory,technology and practice,but few studies have taken into account the impact of climate change.This paper takes the Hebei province with typical semi-humid and semi-arid climate,and Guangdong Province with the humid climate as a case study,and the eight climatic indicators,including temperature,precipitation,potential evapotranspiration,drought index,extreme precipitation and extreme drought,were analyzed in 230 cities of two provinces from 1958 to 2016.And this paper discusses the characteristics of urban climate from two angles of time and space.Urban climate characteristics was discussed from two angles of time and space and the countermeasures of urban drought and flood risk are put forward in two provinces through three aspects: Characteristics of low impact development facilities,urban design rainfall and urban drought and flood risk assessment.According to the results of this study,the cities in Hebei Province has lower temperature,less precipitation,less evapotranspiration,less frequency but strong intensity of extreme drought events,and less frequency and intensity of extreme precipitation events.However,the cities of Guangdong Province,usually have the characteristics of high temperature,plentiful rainfall,high evapotranspiration,and the frequency of extreme drought events is high while the intensity is low,and the frequency and intensity of extreme precipitation events are relatively high.All the climate indexes of the cities show significant positive spatial correlation,but the correlation of the other indicators is complex and the anomaly distribution is chaotic except that the correlation of temperature is more robust and stable.The overall trend of all cities is warming and evapotranspiration decreased,most cities in two provinces have a tendency to become moist,but extreme drought events in Guangdong are becoming increasingly serious.The frequency and intensity of extreme precipitation events in Hebei province are decreasing.Within 59 years,only temperature,potential evapotranspiration and extreme drought frequency were mutated,but including precipitation,potential evapotranspiration and drought index,most of the indicators had periodic characteristics on different time scales.In addition,according to the risk assessment,cities with high waterlogging(drought)risk are often faced with low drought(waterlogging)risk,but cities with moderate waterlogging risk may have three types of droughts.At the same time,in order to prevent the occurrence of drought and flood disaster effectively,the design rainfall of cities in Hebei range from 11.10 mm to 28.26 mm,for Guangdong province is from 18.67 mm to 33.50 mm.In addition,the development direction of different types of cities in the management of rain flood should be different from water storage to drainage.