Abstract

Water table rise near a cliff may trigger a landslide due to the associated increase pore pressure and decrease in frictional resistance. One main cause of water table rise is intense irrigation for agriculture in arid and semi-arid regions. One such case is in Majes, southern Peru, where a landslide has evolved near an intensively irrigated agricultural area. Mitigation strategies for landslides exist, such as physical strengthening of the cliff, but can be expensive. We describe a groundwater management approach to reduce the pore pressure in the vicinity of the cliff to either slow the propagation of an existing landslide or prevent the initiation of a new landslide. A 3D numerical groundwater flow model was built for the Majes area which employs the limited data existing on the local hydrogeology. Simulations were run to understand the connection between the hydraulic properties and the water table level change due to irrigation and pumping. Results show that through a series of pumping wells near the cliff edge, the pore pressure can be decreased effectively. Moreover, decreasing the water table via pumping can be accomplished in 25–35% of the time it took to elevate the water table level by irrigation. In addition, the pumping can capture water that could be reused for irrigation. Thus, based on our analysis, we conclude that wells could provide a groundwater management approach that keeps the pore pressure at low levels to mitigate landslide processes and simultaneously supplies water for irrigation existing and future irrigation-heavy agriculture in semi-arid environments.

中文翻译：

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通过地下水管理和有限的水文地质数据来稳定斜坡：秘鲁南部马赫斯的案例研究

摘要

由于相关的孔隙压力增加和摩擦阻力减少，悬崖附近的地下水位上升可能引发山体滑坡。地下水位上升的主要原因之一是干旱和半干旱地区农业的密集灌溉。其中一个案例发生在秘鲁南部的马赫斯，那里的一个密集灌溉农业区附近发生了山体滑坡。缓解山体滑坡的策略是存在的，例如对悬崖进行物理加固，但成本可能很高。我们描述了一种地下水管理方法，可降低悬崖附近的孔隙压力，从而减缓现有滑坡的蔓延或防止新滑坡的发生。利用当地水文地质方面现有的有限数据，为 Majes 地区建立了 3D 地下水流数值模型。进行模拟是为了了解水力特性与灌溉和抽水引起的地下水位变化之间的联系。结果表明，通过在悬崖边缘附近设置一系列抽水井，可以有效降低孔隙压力。此外，通过抽水降低地下水位只需通过灌溉提高地下水位所需时间的 25-35%。此外，抽水可以收集可重复用于灌溉的水。因此，根据我们的分析，我们得出结论，井可以提供一种地下水管理方法，将孔隙压力保持在较低水平，以减轻滑坡过程，同时为半干旱环境中现有和未来灌溉重度农业的灌溉供水。