地貌发育动力特征是探索流域产沙机制的基础.位于鄂尔多斯台地北缘和河套盆地之间的"十大孔兑"是黄河内蒙古段的十条重要支流(孔兑,季节性洪水沟,蒙古语).流域内存在严重的风-水两相侵蚀作用,产沙量大,对入汇段黄河的输水输沙过程产生重要影响.本文以DEM数据为依据,采用数学函数形态拟合、河长坡降指数分析以及Hack剖面分析的方法,并结合区域地质和气候特征方面的数据,对流域主河道纵剖面的形成和演化特征进行了分析.结果显示:除了壕庆河之外,孔兑各流域主河道纵剖面目前均表现为指数函数拟合形态,处于侵蚀演变的早期阶段;纵剖面指数函数的拟合度自西向东呈下降趋势,而对数函数拟合度则呈现上升趋势,说明其发育程度在该方向上趋于增高,产沙量随之减小;孔兑各流域构造活动性普遍较弱,并存在自西向东降低的趋势;纵剖面平均高程与莫霍面平均深度,河长坡降指数平均值(SL)与纵剖面指数函数拟合系数关系均很密切,表明纵剖面特征的基本格局受内营力特征影响;Hack剖面特征表明各流域均处于隆升状态,其中西部孔兑流域高于东部;从纵剖面演化的时空模式上讲,孔兑流域东部和西部的差异性隆升大致出现在上新世前后,西部孔兑流域海拔增长较快,使得纵剖面因受侵蚀而降低的高程得以弥补,而东部流域纵剖面由于隆升速度慢,外营力的作用效应相对凸显,纵剖面下凹较甚,演进程度相对较高.%The characteristics of landform dynamics are critical of understanding the sediment yield processes. The Yellow River has 10 tributaries, known as Ten Kongduis ( Kongdui is the name of an ephemeral creek in Inner Mongolian) , located between the North Ordos platform and the Hetao Basin in Inner Mongolia, China. Owing to strong interaction between wind and water erosion, and a high sediment yield in the basin, the sediment transport process of the Yellow River has been considerably affected, and it is raising geographer’s awareness. In this study, the characteristics of the stream profiles of Ten Kongduis were analysed using DEM( digital elevation model) data through curve-fitting and calculating the stream length-gradient index ( SL ) as well as the Hack profiles. In addition, it investigated the relations of the characteristics of the stream profiles with the geological and climatic factors. The fitted functions showed that most mainstream channel profiles were characterised by an exponential function form, suggesting that these profiles were at the early stages of erosion evolution and their upper reaches would been eroded for a long term, with the lower reaches receiving the transported sediments. The correlation coefficients of the exponential function decreased, whereas those of the logarithmic function fitting the profiles increased from west to east, indicating that the development level of the profiles increased in this direction. The sediment yield of a basin reduced with a rise in the development level of the mainstream profile of the basin. The average SL values showed that the tectonic activity of the basins was generally weak and its intensity decreased from west to east. The relations between the average heights of the profiles and Moho depth as well as between the average SL values and the determination coefficients of the exponential function were all statistically significant, suggesting that the basic pattern of profile features was affected by the internal force. Furthermore, the Hack profiles showed that all these basins were being uplifted and that the uplift rate of the western kongdui basins was greater than that of the eastern ones. Based on the temporal and spatial evolution patterns, the difference in crust uplifting between the east and the west was found to have occurred since the Pliocene. The western basins rose faster than the erosion rate. In contrast, the eastern basins rose slowly, and the effects of external agents became relatively prominent, leading to their mainstream profiles possessing a relatively high degree of evolution.
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