DEM-based identification of fluvial knickzones and its application to Japanese mountain rivers
DEM-based identification of fluvial knickzones and its application to Japanese mountain rivers
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DOI：
10.1016/j.geomorph.2006.01.018
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发表时间：
2006-08
期刊：
影响因子：
3.9
通讯作者：
Y. Hayakawa;T. Oguchi
中科院分区：
文献类型：
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作者：
Y. Hayakawa;T. Oguchi
利用GIS和50米数字高程模型研究了日本中部山区基岩河流的水流梯度，以讨论断层带的分布。根据测量长度，梯度分为局部类型和趋势类型。从局部梯度到趋势梯度的过渡率，即梯度随测量长度的增加而减小的速率，然后获得作为河流段的相对陡度的指标，这允许客观地识别河流结带。在研究区域内，已识别的结带广泛存在，表明结带是日本山区河流中常见的地貌之一。在河流的上游陡峭的河段，受到活跃的侵蚀和快速的岩石隆起，更丰富的knickzone。这表明，水力起源的knickzones，这是类似的步骤池形态，但在更大的规模。另一方面，皮埃蒙特地区的一些断层带可能与山脚下的构造断裂相一致。虽然火山活动对构造破碎带的形成有一定的影响，但区域岩性对构造破碎带的丰度影响相对较弱。断裂带更符合其他当地机制的河流侵蚀，包括达到规模的过程。
Stream gradients of mountain bedrock rivers in central Japan were examined using GIS and 50-m digital elevation models to discuss the distribution of knickzones. The gradients are classified into local and trend types based on the measurement lengths. The transition rate from the local to trend gradients, i.e. the decreasing rate of gradient with increasing measurement length, is then obtained as the indicator of relative steepness of a river segment, which permits the objective identification of fluvial knickzones. The identified knickzones occur widely in the study area, and indicate that the knickzone is one of the common landforms in Japanese mountain rivers. The knickzones are more abundant in steep upstream reaches of the rivers subjected to active erosion and rapid rock uplift. This suggests a hydraulic origin of the knickzones, which is similar to step-pool morphology but on a much larger scale. Some knickzones in piedmont areas can be, on the other hand, consistent with tectonic faulting at the mountain foot. Although some influences of volcanic activities on the formation of knickzones are observed, regional lithology seems to exert a relatively weak influence on the abundance of knickzones. Knickzones are more consistent with other local mechanisms of fluvial erosion, including reach-scale processes.