泾河流域径流-泥沙的尺度效应研究

目的]分析泾河流域径流和泥沙的尺度效应,并通过突变检测确定突变时间点,对比突变前后水沙尺度效应的变化,为气候变化和人类活动对水沙尺度效应研究提供支持。方法]收集整理了泾河流域1958—2013年的水沙资料,基于流域水沙异源的特性,将流域分成南北两个分支,分别探讨2条分支水沙的尺度效应,并通过Mann-Kendall突变检验方法计算出突变时间点,对比突变前后尺度效应的异同。结果](1)南北两分支的径流—泥沙之间的尺度效应具有反向关系。北支(洪德—张家山)的产流模数随面积增加表现为线性增加,南支(三关口—张家山)的产流模数随面积增加表现出对数函数关系,随集水面积增大产流模数先快速减小后缓慢减小。北支的产沙模数随面积增加表现为线性减少,南支的产沙模数随面积增加表现出幂函数关系,即随面积增大产沙模数先快速增加后缓慢增加;(2)突变后水沙都比突变前出现了不同程度的减少,突变前后水沙的尺度效应大部分具有相同的拟合函数关系式,仅南支的产沙模数由突变前的最优二项式函数拟合转变为突变后的线性函数。结论]气候变化和人类活动的共同作用不同程度的改变了泾河流域径流—泥沙的尺度效应。

A Study on Scale Effects of Runoff and Sediment in Jinghe River Basin

Objective] Analyzing the scale effects of runoff and sediment in Jinghe River basin and comparing the changes of scale effect of runoff and sediment before and after mutation, the mutation time point was determined by mutation testing in order to provid support for the study of climate change and human activities on runoff and sediment scale effects.Methods] Collecting runoff and sediment data from 15 hydrostations within the Jinghe River basin during 1958-2013, based on the characteristics of runoff and sediment come from different sources, the Jinghe River basin was divided into northern branch and south branch to explore the scale effects of the two branches of the water and sediment. Then the Mann-Kendall shift testing method was adopted to calculate the mutation point of runoff and sediment in time, the scale effects of runoff and sediment before and after abrupt change were compared to seek similarities and differences.Results] (1) The scale effects of runoff and sediment had a reverse relationship between northern branch and southern branch. Runoff of the north branch(Hongde-Zhangjiashan) was increased linearly with area. Runoff of the south branch (Sanguankou-Zhangjiashan) showed a logarithmic function relationship with area, runoff modulus was decreased rapidly at first and then decreased slowly. Sediment of the north branch was decreased linearly with area increasing, while sediment of south branch showed a power function relationship with area, namely specific sediment yield was increased firstly and then decreased slowly with area increasing; (2) Runoff and sediment within two branches had different degree of reduced after abrupt change. Most of scale effects kept the same fitting function as before abrupt change, only specific sediment yield of the south branch alters the optimal fitting from binomial function to linear function.Conclussion] The scale effects of runoff and sediment of Jinghe River basin had been changed by climate change and human activities.