Evolvement Of Rainstorm Event And Risk Analysis Of Crop Waterlogging In Huaibei Plain Of Anhui Province

Under the influence of climate change and human activities,the decreasing stability on weather system has led to the growing frequency and impact of extreme precipitation events in recent years,as well as the increase in probability of agricultural rain-waterlogging disaster,all which have caused serious harm on agricultural production in China.Taking Huaibei Plain of Anhui Province with frequently occurred rain-waterlogging disaster as the research area,taking geographic information technology as the platform,this article analyzes the historical evolution characteristics of isolate rainstorm events under climate change.Moreover,by typical crop experiments,it also elaborates the disaster-causing mechanism of rain waterlogging events.It establishes the indicator about isolate rainstorm causing waterlogging,so that people can deal with the waterlogging disaster comprehensively,based on estimation on the risk of future rainstorm.The main conclusions are as follows:(1)Temporal and spatial evolution characteristics and regularity analysis on the isolate rainstorm events:In the eontext of elimate change,the rainfall,duration and frequency are increasing on the whole.During the period from 1995 to 2000,the indicators of the rainstorm mutated;the high incidence area of isolate rainstorm events are showing the expansion trend of the whole basin from"point" to "surface".In general,the torrential events show characteristics of "Peak backwards" and"bimodal" in time.While in pace,in the past 20 years,the torrential events have showed that the entire research area fully entered into the rainstorm enveloped stage with long time and high frequency,facing high risk of rain-waterlogging.(2)Analysis of rain-waterlogging disaster mechanism based on crop experiments:For two major waterlogging factors of too shallow groundwater depth and excessive rain-waterlogging ponding,combining microcosmic tests with isolate rainstorm events,it has obtained the criteria for draining subsurface water that the groundwater level should be dropped to belowground 0.25?0.3m in three days after the rain,while in other period,the groundwater level should be dropped to 0.5 m in three days after the rain.(3)Analysis of rainstorm event characteristics during crop rain-waterlogging sensitive period:Each indicator of rainstorm is also at high risk meanwhile in the stage of waterlogging susceptibility to crops.Years of practice and experience shows that a heavy rain can be infiltrated into the earth,s surface with only about 5 hours,while back to 0.5 meters at least 6 to 15 days.This makes the impact of the second isolate rainstorm event will be superimposed in the research area,under circumstance that the impact of the first isolate rainstorm event doesn't subside,greatly exceed the limit waterlogging capacity of crops with high risk of disaster.Moreover,the impact of climate change will make this "bad-bad" combination develop to a higher risk direction.(4)Construction of rainstorm waterlogging index and the temporal and spatial distribution characteristics:The frequency of rain-waterlogging disasters at all levels has showed the increasing trend over the years in Huaibei Plain of Anhui Province,whose linear tendency is 8.99/10a.It is high incidence period of rain-waterlogging from June to August in the research area,and the problems of rain-waterlogging are more serious in 1990s?2000s.In the southeastern and central regions of research area,floods are more frequent and mostly Light waterlogging.As a whole,the water logging risk of rainstorms "Wide and extreme,is increasing constantly.(5)Forecast of future trends on isolate rainstorm events for Huaibei Plain of Anhui Province:Selecting these three emission scenarios of RCP2.6,RCP4.5 and RCP8.5,as well as two modes of IPSL-CM5A-LR and MIROC-ESM-CHEM,it estimates the risk of isolate rainstorm events for the crop growing season(April to October)in 2020-2050.On the whole,the enveloped area of high risk area is being increased in each mode,the risk of rain-waterlogging will increase in the future in Huaibei Plain of Anhui Province.(6)Comprehensive response to the rain-waterlogging disaster in Huaibei Plain of Anhui Province:Based on statistics of historical literature and the status of waterlogging control project in research area,this paper systematically analyzes the stategy of "three inundation,two waterlogging,three control" which is adapted to the central and southern regions of Anhui Huaibei Plain,as well as the three-dimensional engineering system which is adapt to combine with the discharge policy of"three inundation,a waterlogging,three control,in the northern region of Anhui Huaibei Plain.At the same time,from the perspective of risk coping,it puts forward the general idea of dealing with rain-waterlogging disaster for Anhui Huaibei plain area.