黄河中游黄土覆盖区河流入汇角的特征研究

The Junction Angle Features of Loess-covered River Networks in the Middle Reach of Yellow River

采用正交回归法计算了黄河中游黄土覆盖区河网的入汇角,并分析了其统计特征、空间分布特征和主要影响因素,建立了河流入汇角与流域水系发育机理间的联系.研究区域内,河流入汇角近似正态分布,空间上具有明显的自东南向西北递增的趋势,整体均值相比其他位于相似气候区的河网偏大.相关关系分析表明,河流入汇角与地形坡度和河道凹凸程度的相关性强于降雨量,干旱度指数在研究区域内部的差异对河流入汇角没有显著影响.河流入汇角的空间变异一定程度上反应了水系发育过程中坡面过程和流水侵蚀相对强度的差异.

The orthogonal regression method was used to calculate the junction angles of river networks in loess-covered areas in the middle reach of Yellow River.The statistical characteristics and spatial distribution of junction angles were analyzed,as well as the impacts of environmental conditions,which revealed the link between river network development processes and junction angles.The results show that the junction angle in the study area has approximately normal distribution,with an obvious spatial variation that increasing from southeast to northwest,and the overall mean value is larger than that of other river networks in similar climatic regions.The correlation analysis shows that the junction angle is more strongly correlated with slope and concavity than with rainfall,and the variation of aridity index within the study area has no significant influence on the junction angle.The spatial variation of junction angles indicates the switch of dominance between hillslope processes and fluvial processes during landscape evolution and river network development.