Spatial patterns of old, deep-seated landslides: a case-study in the northern Ethiopian highlands
Spatial patterns of old, deep-seated landslides: a case-study in the northern Ethiopian highlands
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DOI：
10.1016/j.geomorph.2008.09.027
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发表时间：
2009-04
期刊：
影响因子：
3.9
通讯作者：
M. Eeckhaut;J. Moeyersons;J. Nyssen;A. Abraha;J. Poesen;M. Haile;J. Deckers
中科院分区：
文献类型：
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作者：
M. Eeckhaut;J. Moeyersons;J. Nyssen;A. Abraha;J. Poesen;M. Haile;J. Deckers
在过去十年中，埃塞俄比亚北部Geba-Werei集水区500平方公里的研究区域报告了斜坡坍塌，在该地区，山体滑坡以前并不被认为是重要的危险。然而，现场观察显示，许多失败实际上是在土地利用变化后旧的深层滑坡重新激活。因此，本研究(1)探讨控制滑坡发生的环境因素的重要性；(2)评估未来滑坡的易感性。通过航空照片解译和实地核查得出的研究区滑坡清单地图显示了57个滑坡和6个多滑坡地带的位置，主要是复杂的滑坡和泥石流。总体而言，该地区14.8%的地区受到了旧滑坡的影响。在滑坡易感性建模中，应用了证据权重(WOFE)，得到了5种不同的模型。在对模型进行比较并利用接收器工作特征曲线和Kappa值进行空间验证后，选择了一个结合了高程、坡度、坡向、地质和到断层距离的数据的模型。这一模型证实了我们的假设，即深层滑坡位于中等坡度(即5°-13°)的山坡上。预计枯竭区位于高原边缘及其沿线，那里发现了富含蒙皂石粘土的风化玄武岩，滑坡碎屑预计将堆积在阿姆巴阿拉丹砂岩和安塔洛上部石灰岩上。由于未来的山泥倾泻相信会发生在与发生深层山泥倾泻的山坡相似的天然不稳定山坡上，分类的山泥倾泻易感程度图可划定人为干预降低斜坡稳定性可能导致斜坡崩塌的区域。所获得的结果表明，所应用的方法可以用于类似的地区，在这些地区，关于滑坡位置的信息对于当今的危险分析是必不可少的。
During the last decade, slope failures were reported in a 500 km2study area in the Geba–Werei catchment, northern Ethiopia, a region where landslides were not considered an important hazard before. Field observations, however, revealed that many of the failures were actually reactivations of old deep-seated landslides after land use changes. Therefore, this study was conducted (1) to explore the importance of environmental factors controlling landslide occurrence and (2) to estimate future landslide susceptibility. A landslide inventory map of the study area derived from aerial photograph interpretation and field checks shows the location of 57 landslides and six zones with multiple landslides, mainly complex slides and debris flows. In total 14.8% of the area is affected by an old landslide. For the landslide susceptibility modelling, weights of evidence (WofE), was applied and five different models were produced. After comparison of the models and spatial validation using Receiver Operating Characteristic curves and Kappa values, a model combining data on elevation, hillslope gradient, aspect, geology and distance to faults was selected. This model confirmed our hypothesis that deep-seated landslides are located on hillslopes with a moderate slope gradient (i.e. 5°–13°). The depletion areas are expected on and along the border of plateaus where weathered basalts rich in smectite clays are found, and the landslide debris is expected to accumulate on the Amba Aradam sandstone and upper Antalo limestone. As future landslides are believed to occur on inherently unstable hillslopes similar to those where deep-seated landslides occurred, the classified landslide susceptibility map allows delineating zones where human interventions decreasing slope stability might cause slope failures. The results obtained demonstrate that the applied methodology could be used in similar areas where information on the location of landslides is essential for present-day hazard analysis.