Groundwater recharge in Africa: identifying critical thresholds

开发地下水用于安全饮用水、灌溉和其他用途，为改善许多非洲人民的生活提供了巨大的潜力。最近的研究表明，非洲大部分地区都有地下水，地下水资源超过湖泊和河流中的水资源。然而，一个关键的不确定性是地下水抽取的可持续性如何：地下水是否得到补充，如果得到补充，补充量有多大，未来这种情况会发生变化吗？该研究项目将汇集一个由非洲、欧洲和美国科学家组成的团队，研究非洲各地地下水补给的所有现有证据。该团队将使用这些数据来搜索关键充电阈值的存在：超过该阈值充电可能不会发生或变得不可靠的条件。他们将利用该数据集绘制一张非洲观测到的地面水补给量地图，并寻找整个非洲大陆的系统性变化。该小组还将利用这一机会研究测量地下水补给的不同方法，并确定最适合非洲条件的方法。他们将与社会科学家一起利用研究结果，突出地下水补给可能成为可持续地下水抽取的主要制约因素的地区和未来情景，以及威尔斯或钻孔可能干涸，特别是对农村贫困人口的影响。地下水补给图和临界阈值的量化可以有许多不同的用途：它们应有助于量化地下水开发的风险，并管理取水的权衡，以造福穷人;对于在非洲工作的水工程师，他们应该允许对地下水补给进行第一次评估，以筛选补给是否可能成为项目的主要制约因素，也提供了更准确地测量补给的工具;对于学术界来说，这些新的数据集可用于验证全球或大陆尺度的陆面水文模型。研究完成后，水援助组织将召开研讨会和网络研讨会，帮助探讨研究结果对非洲新水项目规划和实施的影响。研究结果将作为一个出发点，设计一个大型跨学科研究的实地项目，以研究导致这些关键补给阈值的过程，从而更可靠地预测地下水开发可能发生的地方。我们将继续努力，以确保未来地下水变得不可持续，并探讨如何在这些关键地区最好地管理地下水。

The development of groundwater for safe drinking water, irrigation and other uses offers huge potential for improving the lives of many African people. Recent research showed that groundwater was present in most parts of Africa and represented a resource greater than the water available in lakes and rivers. However, a key uncertainty is how sustainable groundwater abstraction will be: is it being replenished and if so by how much and will this change in the future?This research project will bring together a team of African, European and US scientists to examine all the available evidence for groundwater recharge across Africa. The team will use these data to search for the existence of critical recharge thresholds: conditions beyond which recharge may not occur or become unreliable. They will use the datset to develop a map of observed groundater recharge volumes for Africa and look for systematic changes across the continent. The team will also use the opportunity to examine the different methods for measuring groundwater recharge and identify the most appropriate for African conditions.Together with social scientists they will use the results of the research to highlight areas and future scenarios where groundwater recharge may become a major contraint on sustainable groundwater abstraction, and where wells or boreholes may run dry, impacting particularly on the rural poor. The maps of groundwater recharge, and the quantification of critical thresholds can have many different uses: they should help quantify the risks of groundwater development and manage tradeoffs in abstraction for the benefit of the poor; for water engineers working in Africa, they should allow a first pass assessment of groundwater recharge to screen whether recharge may be a major constraint on a project, and also provide the tools for measuring recharge more accurately; for the academic community these new datasets can be used to validate global or continetal scale land surface hydrological models. Once the research is completed a workshop and webinar convened by WaterAid will help explore the implications of the research results for planning and implementing new water projects in Africa.The results of this research will be used as a springboard to design a large field programme of interdisciplinary research to examine the processes which lead to these critical recharge thresholds to allow much more reliable forecasts of where groundwater development may become unsustainable in the future and to explore how groundwater can be best managed in these critical areas.