Study On The Spatial-Temporal Distribution Characteristics Of Extreme Precipitation In Recent 5 Years In Mainland China And Its Relationship With Secondary Disasters Based On GSMaP Data

The situation of secondary disasters caused by extreme precipitation in China is not optimistic.With the increase of population and the development of social economy,the economic carrying capacity per unit area,infrastructure,material wealth and other exposure levels are constantly increasing,and the mountain flood disaster,urban flood disaster and other extreme precipitation secondary disasters are increasingly serious,causing huge losses of national interests and people's lives and property.Starting from the extreme precipitation that has attracted great attention in recent years,GSMaP remote sensing precipitation products on daily scale and hourly scale are adopted.Python and extreme precipitation index are used to analyze the spatial and temporal characteristics of extreme precipitation in recent five years in mainland China,and the influence of geographical environment on extreme precipitation is analyzed by combining the data of natural environment and social economy.The information of extreme precipitation secondary disasters was extracted from the micro-blog data,and the geological disaster information was actually surveyed in typical regions to study the relationship between extreme precipitation and secondary disasters.In order to provide reference basis for regional coordinated development and flood control and water conservancy construction in China.The following conclusions are obtained:(1)GSMaP precipitation remote sensing products have real reliability in mainland China.(2)China's extreme precipitation has very regular zonal characteristics.Heavy precipitation in southern China has many times,long continuous time and time dispersion.In north China,the ratio of extreme precipitation to annual precipitation is high,the intensity is high,the concentration of heavy precipitation is high,the risk of flood disaster is high,and the total duration of precipitation is relatively small compared with other regions,which also reflects the obvious drought characteristics in north China.The annual precipitation in Tibet is long,the intensity of extreme precipitation is low,the concentration is high,and the dry and wet seasons aredistinct.The average daily precipitation concentration in most parts of northwest and northeast China is relatively high,which shows the non-uniform distribution characteristics of precipitation process in these areas.(3)The annual precipitation in the study area is stable,and the precipitation intensity in the northern region,especially in the north china-huanghuai region,shows an increasing trend.The north China-huanghuai region is relatively dry,but the intensity of extreme precipitation is large and the duration is short.Extreme precipitation is more concentrated in the north than in the south.The annual precipitation in south China showed no obvious change trend,the precipitation duration showed an increasing trend,and the extreme precipitation showed a centralized trend.(4)Coastline distance,topography,elevation,topographic relief,and socio-economic level have an impact on the extreme value and total value of precipitation.Ocean atmosphere and elevation have great influence on extreme daily precipitation and extreme hourly precipitation,and topographic relief has synergistic effect on other factors.Temperature zone and elevation have higher explanatory power to the total duration of precipitation.Due to the influence of ocean and atmosphere,the precipitation extreme value and annual precipitation in the east of qinghai-tibet plateau show an obvious trend of eastward growth,and the precipitation extreme value in the west side of the mountain is higher than that in the east side of the mountain,while the annual precipitation in the east side of the mountain is higher than that in the west side.The extreme value of precipitation in the inland basin area is higher than the adjacent mountain,while the duration of precipitation and precipitation is lower than the adjacent mountain.In the eastern margin of qinghai-tibet plateau,with the abrupt change of topography,the annual precipitation and the total duration of annual precipitation have obvious high-value abrupt change.The annual precipitation and duration of annual precipitation in junger basin are low,but the extreme value of precipitation is high.In regions with high intensity of extreme precipitation,the per capita GDP and population density tend to be higher,and urban development has a significant positive correlation with short-term heavy precipitation.When the city reaches a certain scale,the extreme value of urban precipitation will be higher than the surrounding area,and thus it is easy to form urban rainstorm.(5)The distribution pattern of extreme precipitation secondary disasters is aggregation,and the geographical environment of different types of disasters is different.Geographically,the flood disaster events are mainly distributed in the eastern coastal areas of China,and the landslide and debris flow disaster points are mainly distributed in the topographic undulating areas of southwest China and the eastern part of northwest China,which are consistent with the general situation of the study area.The specific geological environment conditions determine that the geological disasters in this area are in a long-term high incidence.In terms of geographical environment,floods are mostly distributed in areas with low altitude,flat terrain,sparse vegetation and close proximity to the sea in China,posing a great threat toareas with more developed economy and higher population density.Landslides and mud-rock flows are mostly distributed in areas with large topographic relief and sparse vegetation in China.(6)The precipitation extreme value of secondary disasters has obvious spatial differentiation and is sensitive to short-time heavy precipitation.Compared with landslides and debris flows,flood hazards are more sensitive to maximum continuous precipitation.The maximum daily precipitation,maximum hourly precipitation and maximum continuous precipitation at flood disaster sites were all higher than those at landslide and debris flow disaster sites.In the typical regional analysis,the geological disasters in the bailong river basin are sensitive to the extreme precipitation,and the short-time heavy precipitation is easy to cause the occurrence of the geological disasters,and it is easy to be affected by the surrounding water system.In some areas due to the sparsely populated,often produce floods,landslides and other secondary disasters harmful disaster.(7)Extreme precipitation types of secondary disasters caused by extreme precipitation are different in different regions.Some disaster sites in eastern China,especially those in the northern part of the country,show a relatively high response level to most of the extreme precipitation indexes in the study,among which the response level to the extreme precipitation index on an hourly scale is relatively high,indicating that this region is prone to short-term heavy precipitation.The local disaster sites in the eastern margin of the qinghai-tibet plateau are sensitive to drought,because under the synergistic action of higher annual total precipitation time,the stability of dry soil becomes worse when it encounters precipitation,which is easy to cause geological disasters.Most areas in western China are sensitive to diurnal extreme precipitation index.However,there are still some disaster sites in the east of China,which show a low response level to all extreme precipitation indexes.However,a synergistic effect between the indexes and the environment cannot be excluded.The variation trend of extreme precipitation is different in different regions,and the sensitivity to different extreme precipitation index types is also obviously different.The secondary disasters caused by extreme precipitation should be adjusted to local conditions and corresponding preventive measures should be taken.