Study On The Evolution Of The Base Flow Of The Taoer River Basin And Its Hydrological Lag Characteristics

Studies show that there are significant time delay effects of climate drought and hydrological drought.The differences and delays of runoff and baseflow drought on climate response provide a reliable theoretical reference for dealing with climate drought on river runoff and even maintaining the health of river ecosystems and significance.This study takes the Taonan Hydrological Station in the Taoer River Basin as the research object.Based on the runoff data and daily precipitation data of Taonan Station and 4 meteorological stations from 1960 to 2016,the Chapman-Maxwell method is adopted in the digital filtering method after improving the regression constant.Baseflow separation of the Taoer River runoff process was performed,and the hydrogen and oxygen isotopes measured in the field water are calculated using a Two-terminal mixed water source model method to verify the baseflow separation results.Trend analysis and mutation analysis methods are applied to the Taoer River Meteorological data and hydrological data of the river basin are used to analyze the evolution law;the abnormal conditions of precipitation are used to detect the drought in the Taoer River Basin,and the method of quantifying drought is used to analyze the lag response of the base flow;The characteristics of the baseflow response to precipitation in different scenarios of annual and dry year precipitation events are analyzed.The main results are as follows::(1)When the automatic baseflow identification technology is used to calculate the regression constant(? = 0.984),the baseflow contribution rate is 37.73%,and the empirical value regression constant(? = 0.925)is 48.24%.The content of hydrogen and oxygen isotopes in the Taoer River of the basin is calculated by Two-terminal mixed water source model method to obtain the baseflow contribution rate of 41.6%.The results show that the improved baseflow separation results are more accurate.(2)The annual precipitation in the Taoer River Basin shows a clear upward trend year by year,while the annual runoff and annual baseflow in the Taoer River Basin show a significant downward trend.The results show that the annual runoff process line has two peaks,namely spring flood and summer flood.Based on the data of precipitation,runoff and baseflow in the Taoer River,the abrupt changes in precipitation occurred in 1983,and 2012.The abrupt changes in runoff and baseflow occurred in 1984.The baseflow abrupt change time is different,the runoff and baseflow abrupt change time are the same.(3)Using the frequency of precipitation,the typical years of high,average,and dry years in the Taoer River Basin are determined,which was 1998,1996,and 1997,respectively;under different scenarios,the impact of runoff and baseflow on precipitation The response is different: in base year and flat year,the baseflow has a significant change and the response to precipitation is more obvious;in high water years,the runoff has a significant change,while the baseflow is stable and has no significant change;the baseflow in the spring flood situation The change is relatively stable,and the baseflow changes greatly during the summer flood season.(4)The duration of two meteorological drought events in the Taoer River Basin is 93 months(June 1975 to March 1983)and 137 months(April 1999 to September 2010)respectively.During 1960-2016,there are two periods of drought.The data shows that the second drought lasted longer,spread more widely and is more serious.The lag time between the end of meteorological drought and the end of hydrological drought shows that: runoff recovery(the first and second droughts are 27 and 22 months,respectively)shows a longer lag time than baseflow recovery(the first and second droughts are 28 and 30 months,respectively);during the first and second droughts,the recovery rate of runoff and precipitation is-12.09% and-9.47%,respectively,and base flow drop The water recovery rate is-14.39% and-40.35% respectively.The recovery rate of baseflow precipitation shows the same trend with the time lag of baseflow.