Université de N'Djamena, Laboratoire Hydro-Géosciences et Réservoirs, Campus de Farcha, N'Djamena, Chad; Université de Corse Pascal Paoli, Département d'Hydrogéologie, Campus Grimaldi, BP52, 20250 Corte, France; CNRS, UMR 6134, SPE, BP52, 20250 Corte, France.
Université de Corse Pascal Paoli, Département d'Hydrogéologie, Campus Grimaldi, BP52, 20250 Corte, France; CNRS, UMR 6134, SPE, BP52, 20250 Corte, France.
Sci Total Environ. 2022 Dec 10;851(Pt 2):158152. doi: 10.1016/j.scitotenv.2022.158152. Epub 2022 Aug 18.
Within the Lake Chad Basin, the unconfined Quaternary aquifer offers permanent and easy access to water resources. This transboundary regional aquifer is shared by Chad, Niger, Nigeria and Cameroon and extends over ~500,000 km. Climatic conditions and repeated droughts as well as the intensification of agriculture in the region have multiple negative impacts on the aquifer such as changes in groundwater level and its quality. Being a strategic water resource for the whole Chadian region, the groundwater potential of the Quaternary aquifer must be better characterized and understood to evaluate its resilience to climate change and anthropogenic impact. Stable isotopes and tritium of the water molecule were used to estimate water origin and residence time at the regional scale and to elucidate the interconnections between the different hydrological and hydrogeological components. Results show active recharge processes to the Quaternary aquifer as well as dynamic connections with surface waters (both river courses and wetlands) but also indicate less dynamic behavior of the Quaternary groundwater resource in some areas of the region. Based on the isotopic investigations, the Quaternary aquifer in the Chad basin was found to be resilient to climate change but its hydrogeological specificities (dependence to surface water from the upstream basins and transboundary nature of its structure) can make it prone to inadequate management strategies.
在乍得湖流域，无压第四纪含水层提供了永久性和便捷的水资源获取途径。这个跨界区域含水层为乍得、尼日尔、尼日利亚和喀麦隆共有，延伸面积约 50 万平方千米。气候条件和反复出现的干旱，以及该地区农业的集约化，对含水层造成了多种负面影响，如地下水位和水质的变化。作为乍得地区整个地区的战略水资源，必须更好地描述和了解第四纪含水层的地下水资源潜力，以评估其对气候变化和人为影响的恢复能力。水的分子稳定同位素和氚被用来估算区域尺度上水的起源和停留时间，并阐明不同水文和水文地质成分之间的相互联系。结果表明，第四纪含水层存在活跃的补给过程，与地表水（包括河道和湿地）之间存在动态联系，但也表明该地区的一些地区第四纪地下水资源的动态行为较少。根据同位素调查，乍得盆地的第四纪含水层对气候变化具有恢复力，但它的水文地质特殊性（依赖上游流域的地表水以及其结构的跨界性质）可能使其容易受到不当管理策略的影响。
