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首页> 外文期刊>Journal of Asian earth sciences >Geomorphic threshold conditions for gully erosion in Southwestern Iran (Boushehr-Samal watershed)
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Geomorphic threshold conditions for gully erosion in Southwestern Iran (Boushehr-Samal watershed)

机译：伊朗西南部（Boushehr-Samal流域）的沟壑侵蚀地貌阈值条件

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Globally, a large amount of research has been dedicated to furthering our understanding of the factors and mechanisms affecting gully erosion. However, despite the importance of gully erosion in arid and semi arid regions of Iran there has been no comprehensive study of the geomorphic threshold conditions and factors influencing gully initiation. The aim of this article is to investigate the gullying processes and threshold conditions of permanent gullies in an arid region of Iran based upon examination of the slope-area (S = αA~(-β)) relationship. The data were collected through field and laboratory studies as well as Digital Elevation Model (DEM) analyses. In total, 97 active headcuts were identified across the three study sites and classified based on dominant initiation process including piping, landsliding and overland flow. Soil properties, including EC, SAR and soil texture, as well as landuse practices were found to be the major factors initiating piping and bank gullies. All gullies initiated by landsliding and seepage processes were found to be located in steep areas (28-40% slope) with their distribution further influenced by the lithol-ogy and presence of a cohesionless sand layer within the soil profile. An inverse relationship between upslope area [A] and local slope (S), in which the α and β coefficients varied, was further investigated based on the dominant gullying process and land use. Gullies occurring in the rangelands that were dominated by overland flow had the strongest relationship while landsliding dominated gullies did not have a statistically significant S-A relationship. In comparison to theoretical and literature based relationships for gully initiation, relatively low values for β were obtained (-0.182 to -0.266), possibly influenced by the presence of seepage and subsurface processes in many gullies. However, this is consistent with other studies in arid regions and may reflect greater potential for gullying in arid zones due to low vegetation cover and high variation in rainfall. In addition, the soil attributes together with land use practices influenced gully initiation thresholds. Application of the solved S-A relation for predicting vulnerable areas to gullying indicates that it is possible to predict the location of gullies with an acceptable level of accuracy; however other environmental factors should be integrated with the S-A relationship to more accurately identify the location of permanent gullies in arid regions.
机译：在全球范围内，大量研究致力于增进我们对影响沟壑侵蚀的因素和机制的理解。但是，尽管伊朗干旱和半干旱地区的沟壑侵蚀非常重要，但尚未对地貌阈值条件和影响沟壑萌发的因素进行全面研究。本文旨在研究坡度（S =αA〜（-β））关系，从而研究伊朗干旱地区永久性沟壑的沟壑过程和阈值条件。数据是通过野外和实验室研究以及数字高程模型（DEM）分析收集的。在这三个研究地点总共确定了97个有效的开挖切口，并根据主要的始动过程（包括管道，滑坡和陆流）进行了分类。发现包括EC，SAR和土壤质地在内的土壤特性以及土地利用实践是引发管道和河谷沟壑的主要因素。发现所有由滑坡和渗水过程引起的沟壑都位于陡峭的地区（坡度为28％至40％），其分布进一步受到岩相和土壤剖面内无粘性砂层的影响。根据主要的沟壑过程和土地利用，进一步研究了上坡面积[A]与局部坡度（S）之间的反比关系，其中α和β系数发生了变化。在以高地流为主的牧场中发生的沟壑关系最强，而以滑坡为主的沟壑在统计上没有显着的S-A关系。与基于理论和文献的沟壑萌发关系相比，β值相对较低（-0.182至-0.266），这可能受许多沟壑中渗流和地下过程的影响。但是，这与干旱地区的其他研究相吻合，并且可能反映出干旱区由于植被覆盖率低和降雨变化大而具有更大的沟壑潜力。此外，土壤属性以及土地使用做法也影响了沟壑的起始阈值。求解的S-A关系用于预测沟壑的脆弱区域的应用表明，有可能以可接受的精度水平来预测沟壑的位置。但是，应将其他环境因素与S-A关系结合起来，以更准确地识别干旱地区永久性沟壑的位置。

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