The Research Of Base Flow Process In Mountain Area Of Langchuan River Basin

Base flow is an important part of river runoff and a complex hydrological process.The calculation of base flow division is an important part of water resources assessment in a river basin.In this paper,for the base flow of the Langchuan River Basin in southern Anhui,more than ten base flow segmentation methods are used for calculation,and a method with better fit and stability is selected and applied in this area.Based on the results of the base flow segmentation,the inter-annual,intra-year,and intra-seasonal changes of the base flow are analyzed.Based on the influence of climate and human factors,the evolution characteristics and main influencing factors of river basin base flow were discussed,and then the water balance of the river basin was analyzed.The main conclusions are as follows:This article selects four types of 10 methods that are relatively mature at present to discuss and analyze the base flow of the Langchuan River Basin.The results show that the FI method of the digital filtering method has a good fit,high stability,an efficiency factor of 0.7,and a relative error of 9.33%,which is more reasonable than selecting the digital filtering method F1 method to apply to the Langchuan River Basin.The Dongjin and Xijin river basins,which are similar to the Langchuan river basin,are selected for verification.The results prove that the digital filtering method F1 is reasonable.The base flow segmentation results are used to analyze the evolution characteristics of the base flow in the Langchuan River Basin.The results show that in recent years,the change trend of the base flow in the Langchuan River Basin is basically consistent with the runoff,and the precipitation,runoff and base flow have a relatively decreasing trend In the year,the trend of extreme value difference and extreme value ratio increased relatively.The average uneven coefficient of base flow for many years was 0.36,and the average complete adjustment coefficient for years was 0.16.The annual distribution of the basin was relatively uneven.The main factors of base flow and base flow evolution are climate and human activities.Analysis of climate impact: The annual average temperature in the Langchuan River Basin is increasing year by year.The corresponding annual base flow shows a trend of decreasing year after year,and there is a clear correlationbetween rainfall and base flow.The factors of human activities are the increase of water storage projects and the change of vegetation coverage in the watershed.The construction of the water storage project may significantly reduce the base flow and runoff;the vegetation coverage of the Langchuan River Basin has increased by22.68% in the past 30 years,corresponding to a small change in the base flow in the dry season;the flat water season has significantly decreased The trend of the runoff in the high-water season has no influence.The water balance calculation of the watershed shows that in this watershed,the multi-year average runoff is more sensitive to precipitation than the potential evaporation.The runoff changes in this watershed are mainly affected by precipitation.