关键词: 简单槽谷, 复合槽谷, 简单槽谷段, 复合槽谷段, 单流槽谷段, 梯级宽深比

Abstract: A new model based on the gradient wide depth ratio (GWDR) is posed and the longitudinal variation of glacial valley is presented by using this model on the basis of the investigation and measuring data of the glacial valley cross sections in the middle and west of the Tian Shan Mountains. The GWDR of a glacial valley cross section is defined as the ratio between the distance of the same contour line and its depth in the cross section, and it can describe the integrated characters of a cross section as well as the compared morphological analysis on different cross sections. Statistics show that the relationship between the GWDR and its corresponding depth conforms to the power function. Two parameters ( A f, a measure of the breadth of the valley floor, and B f, a measure of the steepness of the valley sides) are used here to describe this relationship. According to their planar shapes, glacial valleys are classified as single valleys and multi valleys, and multi valleys are subdivided into a simple valley section, a confluent valley section and a single flow section. Base on measuring data of 49 cross profiles of glacial valleys in the middle and west of the Tian Shan Mountains, the longitudinal variations of glacial valleys are concluded as follow: (1) In single valleys, two parameters ( ｜A f｜ and ｜B f｜ ) of the GWDR model increase form the head to the snow line, and the valley becomes wider and steeper in two walls. On the contrary, they decrease from the snow line to the end of the valley, and the valley becomes narrower and gentler in two walls. (2) In multi valleys, ｜A f｜ and ｜B f｜ increase form the simple valley section to the confluent valley section, and decrease from the confluent valley section to the single flow section. These characteristics reflect the differences of glaciation along the valley. The glaciation near the snowline is greater than upstream and downstream in the simple valley because the glacier reaches the maximum values in temperature, thickness, and velocity at this location. In multi valleys, the confluence action becomes the dominant influence factor of the glaciation, so the glaciation in confluence locations is greater than other locations.

Key words: Single valley, Multi valley, Simple valley section, Confluent valley section, Single flow section, Gradient wide depth ratio (GWDR)