华南湿热区小流域水沙变化及影响因子分析——以五华河为例

以韩江上游梅江的一级支流五华河为研究区域,选取近30a来的径流、泥沙和降雨数据,运用累积滤波器、Mann-Kendall、R/S、降水-径流双累积曲线等多种统计模型方法,分析径流、泥沙的年际变化特征、突变和相关关系,并在受人类活动和气候变化影响的基础上,探讨径流、泥沙的变化规律以及贡献率。结果表明:(1)径流年际变化总体略呈下降趋势,但趋势不明显;输沙量则表现出显著下降的趋势;(2)未来年径流量和输沙量可能呈现持续减少的趋势;(3)径流量在1981~1985年、1997~2001年和2004~2008年这3个时段内发生突变;输沙量在1987年发生突变;(4)单位水流的含沙量较少,河床基本处于冲刷状态;(5)降水对径流量变化的贡献率为73%,人类活动对径流量变化的贡献率为27%;输沙量快速减少的变化中,气候变化的贡献率为21%,人类活动的贡献率为79%。可见降水是五华河流域径流量变化最重要的影响因素,而人类活动是输沙量变化最重要的影响因素。

ANALYSIS OF RUNOFF AND SEDIMENT CHANGE AND IMPACT FACTOR IN THE SOUTHERN HUMID AREA RIVER BASIN——A CASE STUDY OF WUHUA

In this paper,Wuhua River,the upper stretch of Hanjiang and the first tributary of Meijiang,was selected as the study area.Based on meteorological and hydrological data over the last 30 years,the paper analyzed runoff and sediment's annual variation tendency,abrupt changes and their relationships,using Cumulative filter,Mann-Kendall (M-K),R/S and Double Mass Curve statistics models and methods.On the basis of human activities and climate change,the paper also explored the relationship between runoff and sediment and contribution rate.The results showed that:1) The runoff amount presented a decline trend of interannual variability,although not obvious;while sediment transport decreased significantly;2) The annual runoff amount and sediment transport may tend to continuously decline in the future;3) The mutational site of runoff is between 1981-1985,1997-2001,and 2004-2008;the mutational site of sediment is 1987;4) The sediment concentration per unit runoff is relatively small,and the river is in the state of erosion;5) The contribution of precipitation to runoff change is 73％,and the contribution of human activities to runoff change is 27％;the climate change's contribution rate is 21％ to the rapid decreasing of sediment discharge while the human activity's contribution rate is 79％.In summary,precipitation is the key factor influencing runoff amount variation,and human activity is key factor influencing sediment discharge.