李琼,,
潘保田,
武佳坤,
吉祥和,
陈泰安
兰州大学资源环境学院, 西部环境教育部重点实验室, 甘肃 兰州 730000
基金项目: 国家自然科学基金项目（批准号：41771002）和国家自然科学基金重点项目（批准号：41730637）共同资助
详细信息
作者简介: 秦冰雪, 女, 24岁, 硕士研究生, 自然地理学专业, E-mail:qinbx18@lzu.edu.cn
通讯作者: 李琼, E-mail:qli@lzu.edu.cn
中图分类号: P931.2;P542收稿日期:2020-08-06
修回日期:2020-11-15
刊出日期:2021-01-30
Evaluation of bedrock corrosion resistance and its influence on channel width in eastern Qilian Mountains
QIN Bingxue,LI Qiong,,
PAN Baotian,
WU Jiakun,
JI Xianghe,
CHEN Tai'an
Key Laboratory of Western China's Environmental Systems, Ministry of Education, College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, Gansu
More Information
Corresponding author: LI Qiong,E-mail:qli@lzu.edu.cn
MSC: P931.2;P542--> Received Date: 06 August 2020
Revised Date: 15 November 2020
Publish Date: 30 January 2021
摘要
摘要:基岩抗蚀性是影响基岩河道宽度变化的重要因素之一，如何合理的评估基岩的抗蚀性一直以来都是地貌学关注的一个难点问题。本研究采用Selby岩性评分方法对祁连山东段地区基岩河道的抗蚀性进行了评估，综合考虑了基岩硬度及节理发育特征等因素对抗蚀性的影响，并在此基础上探讨了岩性对河道宽度变化的影响。研究发现，在河段尺度上，岩性控制着河道宽度的调整变化，但是这种影响是叠加在构造抬升背景之上的，基岩河道形态的变化是构造和岩性共同作用的结果。此外，由于沉积通量双重效应的存在，河宽和比降对构造和岩性扰动的响应表现出明显不同的特征：在沉积供给量较低的河段，宽度与比降协同变化，共同响应扰动；而在沉积供给量较高的河段，河道则以宽度的调整变化为主。
关键词: 基岩河流/
河道宽度/
基岩抗蚀性/
祁连山
Abstract:Lots of empirical researches show that the width of bedrock channel is mainly affected by discharge, rock uplift rates, corrosion resistance of bedrock and sediment supply. Recently, most studies refer to the implications of discharge and rock uplift rates for the channel width, and a few studies on the effect of bedrock corrosion resistance and sediment supply, especially quantitative assessments of corrosion resistance. Therefore, how to reasonably evaluate the bedrock corrosion resistance has always been a difficult problem in geomorphology.
Our study area is eastern Qilian Mountains which located in the northeast of Tibetan Plateau. From the southwest to the northeast, it can be divided into three different topographic zones: the high mountain zone(HMZ), the low mountain zone(LMZ) and the corridor plain zone(CPZ). The rock uplift rate during Quaternary of the HMZ is about twice than the LMZ, and the lithologies are also different due to the various underlying strata in various zones. In the HMZ, there are mainly Caledonian granite and Ordovician metamorphic sandstone. There are Jurassic sandstone, Permian and Triassic sandstone, Cretaceous sandstone in the LMZ. Therefore, eastern Qilian Mountains is an ideal area for the evaluation of bedrock corrosion resistance and channel morphology study. We conducted our research mainly around three large bedrock rivers in the area, and the rivers are as follows:Xiying, Zamu, Huangyang. The trunk stream of Xiying are located in the LMZ, and other channels reaches are located in the HMZ. In addition, although Huangyang is located in the HMZ, its reach is mainly covered by Quaternary pluvial alluvial sediments.
In the paper, basing on the method for evaluating corrosion resistance of bedrock proposed by Selby, we considered comprehensively rock mass strength, joint(spacing, width, continuity and infill), weathering and water permeability to evaluate the corrosion resistance of the bedrock in eastern Qilian Mountains. In addition, we use remote sensing image to complete the missing channel width data of some reaches(the upper reaches of Zamu and Huangyang).
Compared with previous studies, only hardness is used to evaluate the corrosion resistance of bedrock, and the Selby evaluation method used in this paper is more reasonable. Comparing variations of bedrock corrosion resistance and channel width along the three bedrock rivers indicates that: in the more corrosion resistant reaches, channels are narrow, and in the less corrosion resistant reaches, channels are wide. Overall, the change of channel geometry in bedrock river is the result of the combined action of rock uplift, lithology and sedimentary flux. The influence of lithology on channel geometry is superimposed under the background of rock uplift. In some basins or river reaches, the influence of rock uplift and lithology is superimposed and strengthened, while in others, the two counteract and weaked each other. In addition, because of the "dual role" of sediment flux in erosion increases the complexity of channel geometry response disturbance adjustments, which makes the response of channel width and slope to bedrock corrosion resistance significantly different: when the river enters the relatively strong corrosion resistance reach, channel width and slope change together to respond to the disturbance of lithology, and the river becomes narrow and steep; conversely, when the river enters the relatively weak corrosion resistance reach, only the width changes, and the river becomes wide.
Key words:bedrock river/
channel width/
bedrock corrosion resistance/
Qilian Mountains
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