湖南张家界溹水上游河床砾卵石输移分析

An Analysis of Transport of Gravels and Pebbles in the Upper Suoshui River in Zhangjiajie,Hunan

对张家界石英砂岩峰林核心景区溹水上游河床砾卵石的搬运量进行了分析计算.野外实测发现,溹水上游近出口控制断面河床由大于1 cm的砾石和卵石组成.利用河床和流量实测数据,结合日降水序列和实测径流过程流量分布分析,计算得到溹水上游控制断面砾卵石的年均输移量约为1 470 kg/a,模数为20.7 kg/(km2·a).分析认为相对于化学溶蚀和泥沙输移,在现在河床边界条件下,溹水上游的砾卵石输移不是侵蚀搬运的主要形式,这些粗颗粒物质需要经过进一步溶蚀或机械风化和磨蚀细化后,经水流搬运而实现河床的不断下切.

An investigation was made on the transport of gravels and pebbles covering the channel bed of the valleys in the upper Suoshui River where the major part of the marvelous sandstone pillar landscape is located. Measurements reveal that the bed materials of the cross section at the gauging station near the outlet of the upper Suoshui River consist of gravels and pebbles larger than 1 cm. In light of the geometry of channel cross section, bed material composition at the gauging station, and the frequency distributions of the measured runoff and daily precip- itation, the annual mass of gravels and pebbles removed from the channel bed near the outlet of the upper Suoshui River was calculated to be about 1 470 kg/a, which gave a modulus of 20.7 kg/（ km^2·a）. Comparing with the chemical and mechanical denudation rates, the transport of gravels and pebbles is not a main process of rock denudation in the studied area. Under the present channel boundary conditions, these coarse materials need to be diminished by processes of chemical erosion, mechanical weathering, abrasion and pulverization before they can be transported downstream by flows and the river valleys are cut down gradually.