黄河中游流域地貌形态特征研究

The Study of Watershed Topography Characteristics in the Middle Reaches of the Yellow River

黄河中游流经黄土高原的核心区域,对黄河中游流域地貌形态特征的定量分析可以反映黄河中游流域地貌演化进程以及黄土高原侵蚀地貌形态特征。该文以黄土高原区域30m分辨率的DEM为信息源,首先提取了黄河中游7条典型一级支流及其纵剖面,然后计算了6种量化指标分析其流域地貌形态以及流域地貌演化进程,在此基础上,构建地貌特征综合评价指标反映黄土高原区域侵蚀地貌形态特征。实验结果表明,秃尾河、无定河以及延河发育至深切侵蚀期;窟野河发育至深切侵蚀和均衡调整之间的过渡期;汾河、洛河以及渭河发育至均衡调整期。流域地貌随河流侵蚀循环而相应演化,7条河流所在流域的地貌发育程度从北到南也基本呈现逐渐成熟的趋势。所计算的侵蚀地貌综合评价指标值显示,窟野河、秃尾河、无定河以及延河流域共同构成黄土高原强烈土壤侵蚀区;汾河、洛河以及渭河流域的土壤侵蚀程度较低。

T he middle reac:hes of the Yellow River flows through the core areas of the Loess Plateau.T he quantitative analysis of watershed topography characteristics in the middle reaches of the Yellow River can reflect not only the drainage landform evolu-tion process,but also the morphological characteristics of eroded landforms on the Loess Plateau.In this paper,seven typical first-class tributaries of the middle reaches of the Yellow River are extracted from the DEM of30meters resolution through the method of hydrological analysis.On this basis,the longitudinal sections of these rivers are fitted to reflect the development sta-ges.Besides,six quantitative indicators are used to analyze the watershed landform and its evolution process.In addition,the comprehensive evaluation indexes of geomorphic features are constructed to reflect the morphological characteristics of eroded landforms in the Loess Plateau through the method of principal component analysis.According to the experimental results,the Tuw^ei River,Wuding River and Yanhe River have developed into deep erosion period,while the Kuye River has developed into the transitional stage between incised erosion and graded adjustment.Moreover,the Fenhe River,Luohe River and WeiheRiver have developed into a stable stage.The experiment also indicates that the ge.)morphology of the drainage area evolved along with the river erosion cycle.Further,the physiognomy development of the seven rivers is basically showing a mature trend from north to south.T he calculated values of the erosion topographic indexes suggest that the Kuye River,Tuwei River,Wuding River and YanheRiver basins ct^nstitute an intensive soil erosion area in the Loess Plateau,while theFenhe River,Luohe River and Weihe River basins have a lower degree of soil erosion.