One of the major challenges in assessing groundwater vulnerability to pollution is the inadequate factors number and weight. Therefore, to carefully improve the assessment of groundwater vulnerability, a model independent of weight assignment errors was used. Moreover, the specific vulnerability index (SVI) of Sidi Bouzid North's groundwater was assessed in this study. Intrinsic vulnerability index (IVI) assessment was determined in the first step by the arithmetic mean calculation by the index overlay method (IOM) based on the D: Depth of aquifer; P: annual average Precipitation; L: Lithology of the vadose zone and S: percent of Slope (DPLS) model. Then SVI was assessed by linking new factors (LU and NO₃⁻) to IVI. Consequently, 83 samples were analysed for NO₃⁻, showing high values that exceed 50 mg l‾¹. The spatial distribution of IVI shows three vulnerability classes in the study area, namely low (8%), moderate (15%) and high (77%). The evaluation of SVI based on the risks associated with the NO₃⁻ and LU factors using GIS indicates that about 95% of the total study area is classified with high SVI levels. It displayed a good correlation with NO₃⁻ and provided a high discretization of the groundwater risk from natural and anthropogenic pollution. This alarming situation suggests the necessity to apply water-saving irrigation action for adequate water management.

中文翻译：

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使用指数叠加法在突尼斯中部（Sidi Bouzid 盆地）过度施肥下地下水对硝酸盐污染的脆弱性空间变化*

评估地下水对污染的脆弱性的主要挑战之一是因素数量和权重不足。因此，为了仔细改进对地下水脆弱性的评估，使用了一个独立于权重分配错误的模型。此外，本研究还评估了 Sidi Bouzid North 地下水的特定脆弱性指数 (SVI)。内在脆弱性指数（IVI）评估在第一步通过基于D：含水层深度的指数叠加法（IOM）的算术平均值计算确定；P：年平均降水量；L：渗流带的岩性和 S：坡度百分比 (DPLS) 模型。_{然后通过将新因素（LU 和 NO 3} ^-）与 IVI联系起来评估 SVI 。因此，对 83 个样品进行了 NO _3分析^-, 显示超过 50 mg l‾¹ 的高值。IVI 的空间分布显示了研究区的三个脆弱性等级，即低（8%）、中等（15%）和高（77%）。_{基于与 NO 3} ^-和 LU 因素相关的风险使用 GIS 对 SVI 的评估表明，大约 95% 的总研究区域属于高 SVI 水平。它与 NO ₃ ^-显示出良好的相关性，并为自然和人为污染造成的地下水风险提供了高度离散化。这种令人担忧的情况表明，有必要采取节水灌溉行动来进行充分的水资源管理。