| Shibing karst world natural heritage site,has the extremely important outstanding universal value,due to its weak karst ecological environment as well as the summer storm floods occur,the floods in China,and as a result of human the unreasonable use of land vegetation destroyed by large area and a large amount of soil loss,it will also accelerate the soil in this process of rocky desertification in karst region is relatively weak.According to the rainfall data collected from 2014 to 2018 in the Huangzhou River Basin in Shibing,the variation of the annual average monthly rainfall,the variation of the short-duration maximum rainfall and the variation trend of the secondary rain-flood process were analyzed.Based on Huang Zhou river basin water level monitor is measured at the exit 2015 hydrological runoff data of base flow separation using digital filter method for runoff and underground runoff division of surface runoff,proportion of surface runoff,to calculate the years through runoff data,combined with general situation of the lithology and hydrogeological Huang Zhou river basin,basin runoff process,By using the calculation formula of the characteristic value of runoff and confluence and the data of runoff retreat,the characteristic value of runoff and confluence,the coefficient of runoff retreat and the formula of runoff retreat are obtained respectively.The paper provides the decision-making basis for flood control measures in Huangzhou River basin and suggestions and measures for water resources management in karst basin.The main research conclusions are as follows:(1)The rainfall in Huangzhou River Basin has obvious seasonal variations,and the annual rainfall can be divided into rainy season and rainy season.The monthly rainfall in the rainy season accounts for 81.9% of the annual rainfall.The coefficient of variation of monthly mean rainfall in Huangzhou River Basin was 0.7.In recent years,the average annual rainfall in the Huangzhou River Basin has reached1074.04 mm.The number of heavy rain and rainstorm in 2015 is the most in recent years,and the number of heavy rain and rainstorm has been decreasing year by year in recent years,and the total rainfall generated by heavy rain and rainstorm is also decreasing.The annual average number of rainfall days in Huangzhou River Basin reaches 150 days,and the rainfall days are evenly distributed in several years.The maximum daily mean rainfall is unimodal in the year,and the maximum daily mean rainfall is reached in June.The runoff in the Huangzhou River Basin has a certain lag with respect to the fall,and the variation coefficient of the average monthly discharge is 1.18.In the season with little rainfall,especially in winter,the groundwater runoff will replenish the surface runoff in the basin.(2)Variation trend of short duration rainstorm in Huangzhou River Basin.The annual variation of 1/6-hour and 1-hour maximum rainfall in Huangzhou River Basin showed a decreasing trend,while the annual variation of 12-hour and 24-hour maximum rainfall showed an increasing trend.The seasonal variation of 1/6-hour and1-hour maximum rainfall in the Huangzhou River Basin is small,and the maximum rainfall in 12 hours and 24 hours in summer is slightly larger than that in other seasons,while the maximum rainfall in 12 hours and 24 hours in summer is significantly larger than that in other seasons.The 24-hour maximum rainfall is larger than other short-duration maximum rainfall,and the rainfall exists within 24 hours of continuity.The variation coefficient of short-duration maximum rainfall in Huangzhou River Basin ranged from 0.56 to 0.65,and the variation degree was slightly larger.The skewness coefficient of 12-hour and 24-hour maximum rainfall is larger than that of 1/6-hour and 1-hour maximum rainfall,and the dispersion degree of 12-hour and 24-hour maximum rainfall is larger.(3)Characteristics of 10 storm flood processes in the Huangzhou River Basin in2015.The average lag time of sub-flood in Huangzhou River Basin was 5.375 hours.The greater the rainfall intensity,the shorter the duration of the flood.The regression coefficient of Huangzhou River basin is 0.177,and the regression index equation.The secondary runoff coefficient in most basins is less than 0.05.The Huangzhou River Basin is a typical model of superpermeability and runoff production.(4)Variation characteristics of yield and confluence characteristic values in the Huangzhou River Basin in 2015.The annual peak flood discharge in Huangzhou River Basin showed a downward trend.The annual sub-flood volume in the basin is on the rise as a whole.The average monthly runoff coefficient in the basin was 0.28,which showed an overall upward trend in the year.The annual average monthly surface runoff accounted for 29.4%,the overall trend of decline.The average monthly flood peak in Huangzhou River Basin was 7.9 hours,which showed an upward trend.The heavy rainfall in June made the annual peak value of unit line in the basin increase sharply in June,showing a downward trend.The annual mean monthly confluence time of the basin is 22.7 hours,and the annual mean monthly confluence time shows an upward trend. |
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