Analysis On Changes Of Main Hydrometeorologic Factors In The Upstream Of Lijiang River Basin

Runoff is an important constraint on the scale of social and economic development in the region.The ability to manually control and regulate runoff is closely related to the production of regional industry and agriculture,and whether people's lives are affected by floods and droughts.The upper reaches of the LIjiang River Basin are affected by the subtropical monsoon climate.The temporal and spatial distribution of rainfall is extremely uneven.It is more difficult to control the runoff in the Lijiang River Basin.Research on the hydrometeorological factors in the upper reaches of the Lijiang River Basin can reveal the interannual variation characteristics and trends of runoff in the upper reaches of the Lijiang River Basin.It contributes to the development and utilization of water resources in Guilin.And it provides a reference for the use of water resources and ecological protection in the Lijiang River Basin.The changes of runoff in the upper reaches of the Lijiang River in the past 30 years,the characteristics of inflow runoff from the Qingshitan Reservoir and the Jinling Reservoir,and meteorological factors were analyzed.Pearson correlation analysis was used to analyze the correlation between runoff from the upper reaches of the Lijiang River and the inflow runoff of reservoirs and weather factors.According to the data analysis of the runoff in the upper reaches of the Lijiang River,the annual changes in the average annual flow of the upper reaches of the Lijiang River basin are very dramatic,and the interannual change is relatively flat;Through trend analysis,the runoff in the upper reaches of the Lijiang River showed a downward trend,and the trend was significant.However,there is no point of discontinuity in the annual average flow rate in the upper reaches of the Lijiang River.The results of feature change analysis and trend analysis show that the average annual flow of Qingshitan Reservoir and Jinling Reservoir alternates between increasing and decreasing,and the overall trend is decreasing.The runoff of the Qingshitan Reservoir and the Jinling Reservoir has changed significantly during the year,and the rate of average runoff of the reservoir has increased in September and November.The trend changes of annual runoff in Qingshitan and Jinling Reservoirs is basically the same,and they have roughly experienced the cycle of dry ? abundant ? dry.According to wavelet analysis,the characteristics of abundance-dry changes in the time domain of the inflow runoff of Qingshitan Reservoir and Jinling Reservoir are different.Thechange characteristics of weather factors in Guilin City are also different in the time domain.The main cycle of inflow runoff from Qingshitan Reservoir is about 4 years and 17 years,while the main cycle of inflow runoff from Jinling Reservoir is about 6 years,11 years and 19 years.The main cycle of meteorological factor precipitation is 5 years,11 years and 22 years.The main cycle of relative humidity is 10 years and 28 years.The main cycle of maximum temperature is about 22 years and 27 years.The main cycle of the lowest temperature is also around 22 years and 27 years.Pearson correlation analysis results show that the correlation between runoff and rainfall,relative humidity in the upper reaches of the Lijiang River basin is obvious,especially with rainfall.The correlation coefficient r = 0.932,which is a highly positive correlation,but there is no significant correlation with temperature;The runoff from the upper reaches of the Lijiang River basin and the inflow runoff and storage outflow from the Qingshitan Reservoir have passed the 0.01 confidence test,which has a significant correlation.