Foreword to special section: groundwater in Africa.

The vast continent of Africa is a land of contrasts—from the sophisticated urban and industrial centers of Cape Town and Johannesburg to the rural bushlands and mountains of Zimbabwe and Kenya. As in the rest of the world, groundwater resources in Africa are critical to human livelihood, agricultural and industrial development, and maintenance of aquatic ecosystems. Widely available scientific works on hydrogeology in Africa have been relatively few and far between compared with the mass of publications from other parts of the world, from North America and Europe in particular. Over 900 million people live on the continent of Africa, and the range of current groundwater issues is tremendous, from subsistence water supply for basic human needs to geotechnical problems associated with mine dewatering and the infrastructure of urban construction. Likewise, the knowledge and professional skill base for studying and managing groundwater varies from crude outdated resource mapping in some areas to state-of-the-art simulation modeling in others. In assembling this collection of papers devoted to groundwater in Africa, we had two main goals. The first was to bring the technical and scientific issues present in African hydrogeology to a wider scientific audience, and possibly to encourage groundwater scientists elsewhere in the world to tackle projects and research topics relevant to the African situation. The second was to encourage African scientists and their colleagues and students to disseminate their work more broadly. Excellent, innovative