In Tunisia, Groundwater is an important water source for domestic, agricultural and industrial uses, but the deterioration of its quality, under the influence of anthropogenic activities and natural factors, limits its suitability for human consumption and irrigation. The present study was carried out to assess groundwater quality in Bouficha aquifer in north-eastern Tunisia using geochemical, geospatial and statistical techniques. The relationship between groundwater quality and Land Use Land Cover (LULC) patterns were also explored using remote sensing, geographic information system (GIS) and Landsat satellite images. Groundwater samples were collected from sixteen wells in April 2015 and analyzed for their physical and chemical characteristics. Concentrations of major cations and anions in the groundwater vary spatially. The dominant water types in the investigation area are Na-Cl and Ca–SO₄. A basic statistical study, applying hierarchical classification analysis confirms the existence of two groundwater types. To evaluate the suitability of groundwater for irrigation, chemical data were assessed using methods such as Electrical Conductivity, Kelley’s ratio, Sodium Absorption Ratio, Magnesium Hazards, as well as Residual Sodium Carbonate. Regarding drinking groundwater assessment, the World Health Organization (WHO) standards were applied to define sites with drinking water permissible levels. Information was loaded in an ArcGIS software and analyzed with a Spatial Analyst extension using Inverse Spline interpolation methods. Fluoride content in most samples has values as high as 1.97 mg/L, with 53% of the samples showing fluoride concentration higher than the level suggested by the WHO for drinking water of 1.5 mg/L and ratified by the National Society of Exploitation and Drinking Potable Water of Tunisia. Additionally, reported nitrate concentrations are higher than the expected groundwater background level of 10 mg/L; indeed, values are up to 286 mg/L, being hazardous for domestic use and suggesting the presence of anthropogenic sources of water contamination. The Land Use and Land Cover (LULCC) of Bouficha aquifer were changed over seventeen years. The Landsat satellite images have shown that the built-up area increased from 2001 to 2018 to the detriment of water and crop vegetation. The overuse of fertilizers on a total agricultural area of Bouficha aquifer (60%) led to significant pollutants, including nitrate and a deterioration in its water quality. Regarding the WHO and the Tunisian drinking water guidelines, this work provides substantial evidence that groundwater quality is posing a significant health threat for residents. Similarly, results show groundwater’s chemical content is also unsuitable for economic activities in the Bouficha region, mainly hazardous for irrigation purposes.

中文翻译：

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基于GIS和地球化学方法的地下水质量评估：Bouficha（突尼斯东北部）沿海含水层

在突尼斯，地下水是用于家庭，农业和工业用途的重要水源，但是在人为活动和自然因素的影响下，地下水的质量下降限制了其对人类消费和灌溉的适用性。本研究是使用地球化学，地理空间和统计技术对突尼斯东北部Bouficha含水层的地下水质量进行评估的。还使用遥感，地理信息系统（GIS）和Landsat卫星图像探索了地下水质量与土地利用土地覆盖（LULC）模式之间的关系。2015年4月，从16口井中采集了地下水样品，并对其理化特性进行了分析。地下水中主要阳离子和阴离子的浓度在空间上变化。₄。一项基础统计研究，运用层次分类分析，确认了两种地下水的存在。为了评估地下水对灌溉的适用性，使用电导率，凯利比，钠吸收率，镁危害以及残留碳酸钠等方法评估了化学数据。关于饮用水地下水评估，世界卫生组织（WHO）标准适用于定义饮用水允许水平的地点。信息已加载到ArcGIS软件中，并使用反样条插值方法通过Spatial Analyst扩展进行了分析。大多数样品中的氟化物含量值高达1.97 mg / L，其中53％的样品中氟化物浓度高于WHO建议的饮用水中1的水平。5 mg / L，并得到突尼斯国家开发和饮用水协会的批准。此外，据报道硝酸盐浓度高于预期的地下水本底水平10 mg / L；实际上，该值高达286 mg / L，对家庭使用是有害的，并表明存在人为污染源。Bouficha蓄水层的土地使用和土地覆被（LULCC）在十七年内发生了变化。Landsat卫星图像显示，从2001年到2018年，建成区面积增加，这不利于水和作物植被。布菲查含水层的整个农业面积上过度使用化肥（60％）导致了包括硝酸盐在内的大量污染物，水质恶化。关于世界卫生组织和突尼斯饮用水准则，这项工作提供了大量证据，表明地下水质量对居民构成了重大健康威胁。同样，结果表明，地下水的化学含量也不适合布菲查地区的经济活动，主要是灌溉目的。