Variation Characteristics And Prediction Of Annual Runoff Series In The Upper Jing River And The Influencing Factors

Under the combined action of climate change and human activities,the hydrological cycle in the upper Jing River has changed.It has destroyed the consistency of hydrological sequence and caused hydrological variation.Therefore,it is of great significance to study the variation types and locations of variation points of annual runoff series in the upper Jing River,calculate hydrological frequency in different periods,and distinguish the contribution rates of different influencing factors to runoff.The paper was based on the hydrological data of four stations from 1956 to2020 in the upper Jing River.Hydrological variation diagnosis system,the frequency calculation method of inconsistent hydrological series,mathematical statistics,the relations of rainfall and runoff,the SCRAQ method were used to quantify the variation and effects.The main conclusions are as follows.（1）The annual runoff series showed hydrological variation with inconsistency.The annual runoff series of the four hydrological stations showed downward jump variation in 1993,1993,1970 and 1977,respectively.The ranks of variation were medium,medium,strong and strong.（2）Compared with the past period,hydrological statistical parameters in the study area will change in the future,and annual runoff with the same frequency will decrease greatly.In the future,the mean annual runoff will decrease and the Cv and Cs will increase,which is extremely unfavorable to the development and utilization of water resources.（3）Distribution of runoff and precipitation is uneven.The annual distribution of runoff is characterized by more in summer and less in winter,and its process is a single-peak curve.The maximum runoff for four consecutive months occurs from July to October,accounting for about 60% of the whole year.The variation range of Cv is large,indicating the uneven distribution of runoff.The interannual pattern of "abundant-flat-dry" alternates.The seasonal variation of precipitation in the year is large,characterized by more summer and less winter.The proportion of maximum precipitation in 4 consecutive months is 70% of the whole year.The occurrence time is one month earlier than runoff,indicating that runoff has a lag with precipitation.The variation trend of annual precipitation is not obvious and has fluctuation.（4）Both precipitation runoff relation method and SCRAQ method are suitable for studying the contribution rate in the upper Jing River.The result shows that human activities are the main influencing factors to runoff series,accounting for more than three quarters of the total contribution rate.Precipitation,temperature and water consumption all have certain influence on runoff except for land use.（5）In the study area,the vegetation coverage is high and the water consumption increases.The area from large to small is grassland,arable land,woodland,urban and rural land,water,unused land.The water consumption of farmland irrigation accounts for the largest proportion of total water consumption.The increase of urban water consumption and the decrease of water consumption of rural people and livestock are inseparable from the rapid growth of China’s urbanization.