| The Intergovernmental Panel on Climate Change(IPCC)assessment report highlights that climate change profoundly affects water and social security in human society.Precipitation is one of the most important elements in climate and hydrological analysis,and analyzing precipitation change characteristics,including trends,cycles,and annual concentration,is an important basis for studying climate and hydrological change.At the same time,climate change also affects the intensity and frequency of heavy precipitation events,which are prone to triggering flood disasters and are one of the main regional meteorological disasters.This study analyzes the characteristics of precipitation trends,cycles,and annual concentration in Shandong Province based on the downscaled global climate model data from CMIP6.It is found that the precipitation trend in Shandong Province will mainly increase in the future,and the annual precipitation concentration degree in the eastern,central and southern regions has increased in recent years,reflecting the increasing frequency of extreme precipitation events.Furthermore,the study selected the typical basins of the Mihe River basin and the Yihe River basin in Shandong Province,which have experienced more extreme precipitation events in recent years,and analyzed the spatiotemporal variation characteristics of short-duration heavy precipitation.The quantitative analysis method of flood peak superposition comprehensively considering the movement of precipitation center and the process of confluence is put forward,which can provide guidance for flood control and disaster reduction.The study focused on the following two aspects:(1)The characteristics of precipitation trends,cycles,and annual concentration in Shandong Province are analyzed.The multi-model ensemble(MME)precipitation data based on several climate models in CMIP6 was selected for trend and cycle analysis of long-term record and short-term record,respectively.Based on the multi-temporal precipitation trend analysis method,the influence of precipitation sequence selection on precipitation trends was further explored.Using the open-source command-line software CDO,the spatial and temporal characteristics of daily maximum precipitation(RX1day),days of heavy rain(R20)and contribution rate of heavy rainfall(R95C)in Shandong province were analyzed and calculated,and the typical regions with obvious increasing trend of precipitation concentration in the future were screened.(2)This paper analyzes the spatiotemporal variation characteristics of heavy precipitation in the typical basins of the Mihe River basin and the Yihe River basin in Shandong Province,and a quantitative analysis method of flood peak superposition that comprehensively considers the movement of precipitation center and the process of confluence is proposed.Taking the heavy rainfall from Typhoon Rumbia in 2018,Typhoon Lichma in 2019,and heavy rainfall in 2020 as examples,the spatiotemporal variation characteristics of the three rainfalls were analyzed in the Mihe River basin and Yihe River basins.Based on the principle of equal-time flow time,the flood cause analysis method is proposed,and different scenarios of precipitation center movement are set to explore the impact of spatiotemporal variation characteristics of heavy precipitation on downstream outlet peak flow. |
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