A Textual Research On The Huge Historical Floods In The Upper Reaches Of The Hanjiang River In The Northern Song Dynasty

Climate change is one of the important driving forces that lead to the change in ecological environment,social economy and human life,global climate change is growing,extreme weather and climate events,especially the frequency and intensity of flood disasters have increased significantly.The flood disaster has always been one of the most serious natural disasters that plague people's production and life.It has important practical significance for the flood control and disaster reduction to obtain the hydrological sequence of the long time scale river.So far,the domestic scholars continue to use the research methods of ancient flood hydrology,parts of the analysis of some domestic famous rivers and conducted corresponding research,in addition,recovered and rebuilded the occurred age and peak flow of this rivers which have million years scale,This study extends the river hydrological data,It provides a scientific basis for the rational planning of water resources and the formulation of flood control and disaster mitigation policies.Due to the limitations of the existing dating techniques,for the history of the flood and the definition of the flow of time is still unable to accurately.However,our country has a long history,rich historical documents can be well preserved,history of flood disasters in the text,it records long,detailed,involving a wide region;thus,study on the combination of paleoflood and historical flood,textual research on the historical flood and in-depth analysis of historical floods and other extreme climate events,reveal the climate change in the basin during the historical period,it also has a good guiding significance to predict the future climate change.The utility model can improve the accuracy of the occurrence of the large historical flood,and can make up the problem of the short sequence of the measured flood data of the river.The upper reaches of Hanjiang River,located between Qinba mountain areas,is a transitional zone of natural environment and social economy.It is also a sensitive area of climate and environment change."Two mountains terrain structure Yichuan" unique historical period,the upper reaches of the Hanjiang River flood disaster It is often seen.In recent years,along with our group to the upper reaches of the Hanjiang River Hydrological study of ancient flood in-depth,the upper reaches of the Hanjiang River geological period flood event has been found,but limited to the dating techniques,large historical flood occurred in the sedimentary record accurately.The research on the combination of the historical records of the historical documents and the geological profiles is helpful to extend the measured flood sequence,which has important practical significance for the smooth progress of the Middle Route Project of the south to North Water Transfer project.In this paper,based on the research results of flood hydrology of the upper reaches of Hanjiang River in recent years,combined with a large number of historical records,the historical flood records of the Northern Song dynasty recorded in the historical records of the upper reaches of the Hanjiang River are analyzed in detail.With the help of Excel and Arc-GIS software,the characteristics of flood disasters in Northern Song Dynasty are analyzed in terms of the time variation law,spatial variation rule,grade division and influence comparison of flood disaster.Based on the characteristics of flood mark deposits,this paper makes a textual research on the occurrence age and peak flow range of the great historical flood records of the Northern Song Dynasty during the Northern Song Dynasty.Conclusions are as follows:(1)This paper collated the 5 profiles about the flood slack water deposits(SWD)of the largest historical flood in the upper reaches of Hanjiang River during the Northern Song Dynasty,they are LSC-B profile,YJP profile,SJH profile,GXHK profile,and MTS profile.From the point of view of sedimentology and geology of the Northern Song Dynasty is a flood disaster prone period,and there have a large historical flood events.(2)The statistics of historical documents recorded in flood disaster in China in Tang Dynasty to the Yuan Dynasty in the year 750 occurrence frequency,frequency statistics,flood disaster in Northern Song Dynasty in the first,up to 35 times,belong to multiple period of flood disaster.The characteristics of uneven distribution of flood disaster in Northern Song Dynasty,the frequency of flood disaster was found to increase with time going by,especially in the early Northern Song Dynasty,the flood disaster is more frequent.On the flood season and monthly variation,it was found that the flood disaster occurred in autumn,and the frequency was highest in August.Classification and classification of flood disaster,it was found that the flood disaster in this area is mainly caused by the flood,and with the passage of time,the frequency of flood disaster is increasing.Finally,this paper analyzes the impact of flood disaster on the development of agriculture,the degree of social harm and the disaster relief policy of the Northern Song dynasty.These results provide a data base for the study of the historical,flood in the Northern Song dynasty.These results provide a data base for the study of the historical flood in the Northern Song dynasty.(3)This paper analyzed the 3 times severe flood disasters found that the flood disasters involved places about the two floods in Jun.982 and Jul.991 were more widely.Severe flood disasters were involved the entire Hanjiang River Basin in Jun.982 and the upper reaches of the Hanjiang River in Shaanxi province in Jul.991.The severe flood disaster's scope in Jun.982 was more serious than severe flood disaster's scope in Jul.991.Based on the analysis of the degree of disaster and agricultural influence,Jun.982 was more serious than that caused by the flood disaster in Jul.991.In addition,according to historical records,a comprehensive analysis of casualties,from the aspects of agricultural damage caused by the floods,and combined with the flood FLOOD traces of deposition and retention characteristics,research the upper reaches of the Hanjiang River in the Northern Song Dynasty large historical flood may occur in 982 years in June.(4)According to the research group,the peak discharge of the great flood in the geological history of the Upper Hanjiang River was recovered and calculated.This paper sorted out the 5 peak flow values(LSC-B section 47400m~3/s of the peak flow and flood peak flow of 55950 m~3/s YJP section,SJH section GXHK section 62390m~3/s of the peak flow and peak flow of 63090m~3/s,MTS,58620-64270m~3/s profile peak flow)that peak flow range of the upper reaches of the Hanjiang River sediment profile recorded in the Northern Song Dynasty large historical flood is 47400m~3/s-64270m~3/s.(5)The main reasons of flood disaster occurred in the upper reaches of Hanjiang River in the Northern Song Dynasty:The unique climatic conditions and terrain conditions in the upper reaches of Hanjiang river.The upper reaches of Hanjiang River is the most important dividing line between geography and climate in China--on the south side of Qinling Mountains mountain,located in the center of the two big Mountains,Not only the general rainstorm floods occur frequently,but also for a long period of time or a particularly serious flood disaster in the basin has occurred frequently.On this foundation,the permeability of bedrock Canyon is poor,the runoff can not be infiltrated,the summer precipitation is concentrated and the intensity is large,and the runoff flow is fast.In addition,the Northern Song Dynasty is a turning period of climate turbulence,which further induced the occurrence of flood disasters.This paper studies the extreme precipitation events in the upper reaches of Hanjiang River during the Northern Song Dynasty,to compensate for the age of the ancient flood basin were drawbacks imprecise,at the same time as the historical records provide a peak flow interval exactly,this is the for the construction of the effective watershed flood disaster countermeasures and large-scale water conservancy and Hydropower Engineering provides a reliable theoretical support and scientific reference data.