Land degradation of alluvial plains is an environmental risk for groundwater contamination, stemming from the mobilization of contaminants that can occur from waste‐filled gravel pits. This risk can be increased by river damming and consequential rises in groundwater levels. The presence and characteristics of former historical land degradation of alluvial plains should therefore be considered when planning hydroelectric projects. The aim of this study was to assess the hydrological and environmental impacts of the planned damming of the Sava River on the groundwater, which is the drinking water source for the Slovenian capital Ljubljana. It introduces an integrative approach for determining the characteristics of old waste‐filled gravel pits with stereo image processing of historical aerial photographs and electrical resistivity tomography (ERT) in combination with hydrological modelling. Thirty gravel pits in the study area (17 km²) were identified by stereo image analysis, and three were selected to test results in the field using non‐invasive ERT. Integrating this information with the results of hydrological modelling, we assessed the risk of groundwater contamination from the scenario of the planned damming of the River Sava. The results indicate that the thickness of the unsaturated zone below the identified gravel pits will be reduced by an average of 4 m at median groundwater level conditions during damming, which will increase the vulnerability of groundwater to contamination.

中文翻译：

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考虑进行大坝规划的冲积平原土地历史退化导致的环境风险

冲积平原的土地退化是地下水污染的环境风险，源于动员可能由废物填埋的砾石坑产生的污染物。水坝筑坝和随之而来的地下水位上升可能会增加这种风险。因此，在规划水力发电项目时，应考虑冲积平原以前的历史土地退化的存在和特征。这项研究的目的是评估计划中的萨瓦河大坝对地下水的水文和环境影响，地下水是斯洛文尼亚首都卢布尔雅那的饮用水水源。它引入了一种综合方法，通过结合历史航拍照片的立体图像处理和电阻层析成像（ERT）以及水文建模，来确定废旧填满的砾石坑的特征。研究区有30个砾石坑（17 km²）通过立体图像分析进行识别，并选择了三项以使用非侵入性ERT在现场测试结果。将这些信息与水文模型化结果相结合，我们从计划的萨瓦河大坝的方案中评估了地下水污染的风险。结果表明，在筑坝过程中，在中等地下水位条件下，确定的砾石坑下面的非饱和带厚度将平均减少4 m，这将增加地下水对污染的脆弱性。