北江流域径流年内分配特征的变异性分析

以北江流域石角站53年的实测月径流资料为基础,研究了流域内径流年内分配特征及其变异性。计算了径流年内分配不均匀性、集中程度、变化幅度等指标。发现各年代和多年平均相比,20世纪50、60年代的径流年内分配较不均匀,70年代以后,径流年内分配逐渐趋于均匀,集中期和极小比的变化表现为具有波动性。从各指标的变化趋势看,不均匀系数、调节系数和极大比在1967、1975、1999年发生了变化,集中度在1999年发生了变化,集中期在1984、1999年发生了变化,极小比在1975、1983、1991、1999年发生了变化。径流年内分配特征的趋势变化和降雨不一致,主要表现在径流的年内分配不均匀性趋势较降雨降低,径流对降水的滞后时间延长,径流极大比变化趋势较降雨下降,极小比变化较降雨平稳。说明北江流域径流年内分配特征发生了变异。对流域内水利工程设施的修建、植被条件、城市化发展情况进行了分析,认为北江流域径流年内分配特征发生变异,主要是受到了上述人类活动的综合影响。

Variability Analysis of Annual Runoff Distribution Characteristics in Beijiang River Basin

Based on the monthly runoff data of 53 years from the Shijiao Wtation in the Beijiang River Basin, the annual runoff distribution characteristics were studied, and several indices related to the attributes of uneven, concentrate degree and amplitude of variation were calculated. The results show that annual runoff distribution in 1950s and 1960 is uneven, after 1970s it becomes moderate than before, concentration period and minimum ratio change with fluctuation. From the tendency of each index, it shows that non-uniform coefficient, adjustment coefficient and maximum ratio changed in 1967, 1975 and 1999; concentration changed in 1999; concentrated period changed in 1984 and 1999; minimum ratio changed in 1975, 1983, 1991 and 1999. Variation in distribution trend of rainfall and runoff is not the same, trend of uneven characteristic of runoff distribution reduced than rainfall, delay time of runoff to precipitation increased, trend of maximum ratio of runoff decreased than rainfall, change of minimum ratio is smoother than rainfall. Annual distribution characteristics of runoff in the Beijiang River Basin have changed. Construction of water conservancy facilities within the watershed, soil erosion, economic development were analyzed. The result shows that the variation of annual runoff distribution in the Beijiang River Basin is mainly affected by the combination of the human activities.