Extreme Precipitation Events And Flood Risk Assessment In China-Pakistan Economic Corridor

Global climate change will lead to changes in the frequency,intensity and impact range of extreme climate events,and cause phenomena such as extreme precipitation and the increased risk of flood disasters.The ecological environment of China-Pakistan Economic Corridor(CPEC)is complex and it is faced with potential ecological environmental risks and waterlogging loss risks.Therefore,it is necessary to analyze the risk of extreme precipitation events and flood.In this paper,based on measured precipitation data and global climate model simulation data in CPEC.IAD extreme event identification method was used to analyze the evolution characteristics of extreme precipitation events in CPEC during 1961-2013 and under future climate models.The evolution trend of extreme precipitation events under the background of climate change is clarified.Under the influence of extreme precipitation,the flood risk in the study area is evaluated,and the flood disaster is evaluated based on the improved game theory combination weighting.At the same time,the flood inundation simulation is carried out based on the Floodarea model,and the detailed flood inundation data is further obtained,providing a basis for disaster prevention and reduction.Through macro risk analysis and specific inundation simulation,the two mutually corrode the flood risk assessment results of CPEC.The main research results are as follows:(1)From 1961 to 2013,the annual average temperature in the study area increased at a rate of 0.415?/10 a and annual precipitation showed a fluctuating upward trend.Using IAD pattern clustering recognition evaluated different duration of extreme precipitation events.Short duration of extreme precipitation frequency has obviously rising trend,extreme precipitation events are distributed in each month and present obvious double peak phenomenon.The area affected by a single event increased slightly over time,the intensity of precipitation increased,and the extreme phenomenon was significant.(2)Combining the land use data,hydrometeorological data and digital elevation model of the study area to construct a flood inundation simulation model of the Flood Area,and carry out the flood process under the high scenario(once in 100 years)and low scenario(once in 20 years).Simulation shows that the flood inundation risk zoning changes in different return periods,but the overall inundation risk trend is the same.(3)An evaluation index system composed of multiple variables was constructed by comprehensively considering the disaster-inducing factors,disaster-generating environment and disaster-bearing bodies.The optimal combination weight was obtained by using the improved game theory coupled intuitionistic fuzzy hierarchy analysis of subjective weight and objective CRITIC weight,and the study of flood risk variation was carried out.The results show that the flood risk in CPEC is greatly affected by precipitation and topography,and the spatial distribution of flood risk is larger in the southeast than in the northwest.The medium-high risk areas and high-risk areas are basically areas with small topographic changes,dense river network and concentrated population distribution.Therefore,it is necessary to pay attention to the impact and harm of floods on social and economic development in CPEC.The high flood risk area in the region expands with the change of time,and the main factor that causes the increase of flood risk is the occurrence of extreme precipitation.(4)The spatial downscaling deviation correction of the model data of three different combined paths in CMIP6 was used to analyze the variation characteristics of extreme precipitation events and flood risk assessment.The frequency of extreme precipitation events increased at the highest rate under the SSP5-8.5 combined path.In the next 30 years,the average affected area of extreme precipitation events will decrease,while the total affected area will increase,indicating that extreme precipitation events in a small range will increase in the future.The flood risk has an obvious trend of expansion,which is mainly reflected in the expansion of the area of high and medium-high risk areas,and the significant expansion of the medium-high risk areas.The results of the risk zoning obtained by the two different flood risk assessment methods are different,but the overall risk trend is consistent.