呼图壁河基流变化及其影响因素

基于石门水文站实测日径流数据和流域气象资料，运用平滑最小值法和递归数字滤波法对呼图壁河流量过程进行了基流分割研究。在不同的时间尺度上探讨了呼图壁河年均基流量和基流指数（BFI）的变化特征，以及不同水平年基流量与BFI的变化特征，并按照不同水平年份的划分从气温和降水两方面剖析影响基流变化的因素。结果表明：研究区内平滑最小值法优于递归数字滤波法。呼图壁河基流量的年内分布表现为单峰型，7月达到最大值，BFI先减小后增加，5月最小，枯水期BFI接近1。呼图壁河年基流量呈现为增加的趋势，多年平均基流量为3.67×10⁸ m³，多年平均BFI为0.78，呈递减趋势。枯水年份的平均BFI为0.78，平水年为0.76，丰水年为0.74。春秋两季气温和降水对呼图壁河基流量的影响最为显著，不同的水平年份相关系数也存在一定差异。各年份气温对春秋两季基流量的影响均大于降水，说明气温是呼图壁河基流变化的关键性因素。

Variation of the Baseflow and Its Causes of Hutubi River

Based on daily runoff data of Hutubi River Shimen station,the smoothed minimum method and recursive digital filter were used for base flow separation,the recursive digital filter and smoothed minimum method were used for base flow separation.Annual and interannual variations in baseflow,baseflow index (BFI),and the variations in BFI for different water level years in Hutubi River basin as well as the main controlling factors (temperature and precipitation) were investigated in different time scales.It is found that the smoothed minimum method is more suitable than recursive digital filter in the study area.Annual distribution of baseflow is in unimodal type,with the maximum value appearing in July,the BFI distribution in a year,with the minimum BFI value in May.BFI is close to 1 in dry year.The average annual base flow is 3.67×10⁸ m³.The base flow is increasing in the Hutubi river.The base flow index is 0.78 in the study area,it is in slowly decreasing trend.Averaged BFI from the smoothed minimum method in dry years,average years,and wet years were 0.78,0.76 and 0.74,respectively.Temperature and precipitation are two important factors,and their importance to baseflow varies with seasons in different water level years.The results implied that the effect of temperature on baseflow was higher than that of precipitation in spring and autumn.Temperature plays a leading role in the effects on baseflow in spring and autumn,and temperature is a key affecting factor on baseflow of Hutubi River.