DCCA在黄土高原流域径流环境解释中的应用

DCCA Order Applied in Environment Explaining of Watershed Runoff on Loess Plateau

以黄土高原腹地泾河流域12个水文特征指标为“物种”,选取对流域径流有影响的9个环境因子,采用DCCA排序方法定量分析河流径流特征沿环境因子梯度的演变规律。结果表明:(1)DCCA排序的前3轴分别与退化草地比率、降水量、降水强度、植被指数、平均坡度显著相关;(2)河流径流特征沿环境梯度可明显分为输沙量极大的北部黄土丘陵区;平均含沙量极高的中北部黄土沟壑区;径流量大、输沙量小的山地-沟壑过渡区;侵蚀模数极高、径流年内变化极大的中部黄土残塬区;产流量大、年含沙量极低的南部山地区。

CA was used to quantitatively analyze the environmental roles and their effects on the spatial patterns of runoff characteristics. The results are as follows： （1） The first three axes of DCCA order relate to degraded grass land area ratio, rainoff, precipitation intensity, vegetation index and average slope significantly. （2）The runoff characteristics change slowly with environmental gradient and the basin can be divided into five runoff regions based on this. They are north loess hilly region, middle-north loess gully region, middle fragmentary loess plateau region, south mountain region and transition region from mountain to loess gully. （3） Twelve runoff characteristics index show different importance in different regions. Sediment transport ratio and sediment content are the most important in the north loess hilly region and north gully region. Extremely variation of runoff and erosion modulus are main indices in the middle fragmentary loess plateau region. Runoff, the biggest runoff index, the biggest sediment transport index, variation of runoff, variation of sediment transport are very important in the transition region from mountain to loess gully, and runoff modulus, runoff depth andthe biggest sediment content index are main indices in the south mountain region.