| Gully step-pool is a common geomorphology formed by the channel development and evolution,The development of gully step-pool has changed the local datum of gully erosion,increased the longitudinal gradient of gullies,increased the flow power in gullies and intensified the gully erosion,resulting in a great deal of soil erosion and destruction of regional eco geological environment.In this paper,gully step-pool in Yuanmou dry-hot valley is the research object,the purpose of this study is to reveal the characteristics and formation conditions of the gully step-pool,the main idea is:First,we measured the morphological parameters of the gully step-pool in the field,and classified the gully step-pool into different types according to the different main factors causing;Secondly,depicted the morphological parameters of each type of gully step-pool,and analyzed the relationship between the morphological parameters by mathematical method;In the end,analyze the natural factors affecting the development of gully step-pool by field survey datas and theoretical datas.In this study,we used Leica DistoTM D8 laser rangefinder and other instruments to measure 234morphological parameters of gully step-pool in Yuanmou dry-hot valley.After that,we used Microsoft Excel 2010 software to make statistics and draw charts of morphological parameters of gully step-pool.The results show that:(1)The classification of the gully step-pool are:According to the difference of the material characters,the gully step-pool can be divided into mud gully step-pool and stone gully step-pool;According to the different positions of the gully step-pool in the channel,can be divided into gully head step-pool,gully body step-pool and gully mouth step-pool;According to the gully step-pool height or width?80cm,80cm<high or wide?160cm,160cm<high or wide?240cm,240cm<high or wide?320cm,320cm<high or wide,to drop development scale classification(in the same step,the larger the high grade and in width),can be divided into micro gully step-pool,small step-pool,mid step-pool;large step-pool and oversize step-pool;According to the main causes of the development of the gully step-pool,we can divide the step-pool into 4types:the spontaneous step-pool,the induced step-pool,the barred type step-pool and the geologic activity-caused step-pool.(2)The statistical characteristics and grading characteristics of the height,width and aspect ratio of different types,different developmental regions and different development parts are different in the aspect of morphological characteristics and development;In terms of development,the statistical characteristics of the depth of concave cavity and the depth of pool vary from different types of gully step-pool.The statistical characteristics of runoff slope and falling slope length and slope of geological type fall are different from those of classification.Therefore,the morphological characteristics of the gully step-pool in the Yuanmou dry-hot valley of have obvious characteristics of complexity.(3)the step height and depth of pool,concave hole or concave hole depth,width,or there is a positive correlation between the pool length,slope runoff,the parameter values increased with the step-pool height increases,but the correlation is not obvious,the step height and the concave hole width of linear fitting equation R~2,0.3704,shows that in the relationship between step height and the parameters in the step height of the concave hole width effect of growth is the largest,the most significant correlation;The least significant correlation is the relationship between runoff slope and depth of pool.The R~2 is only 0.0205,and the two is almost no correlation,so the impact of step height on runoff slope is also the weakest.There is a positive correlation between the width of the concave hole and the width of the pool and the width of the inner cavity,but the correlation between the width of the step and the width of the concave pool is not as good as the correlation between the width of the step and the width of the concave hole.Therefore,the width of the step has a very weak influence on the width of the pool,but it has great influence on the width of the inner concave hole.There is a positive correlation between the runoff slope and the depth of pool,but the correlation is not very obvious.R2 is only 0.0119,so the influence of runoff slope on the depth of pool can be neglected.(4)The development of gully step-pool in Yuanmou dry-hot valley is mainly affected by the comprehensive influence of erosion datum,tectonic condition,lithologic condition,terrain condition and vegetation factors. |
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