Integration of hydrogeology and social sciences in practice, two IWRM case studies with challenges and opportunities from semi-arid Africa

Groundwater resources in African drylands are important sources of freshwater but are under pressure due to population growth and climate change. It is therefore increasingly important that groundwater resources are managed in a sustainable way. Development of IWRM plans are ongoing in (semi-)arid African countries with support from national governments, NGOs and consultancies. This presentation aims to highlight two case studies in which bio-geophysical and socio-economic data were combined to assist in the Integrated Water Resources Management (IWRM) process: 1) catchment-scale Water Infrastructure Assessment (WIA) in Sudan and 2) assessment of pathways towards sustainable groundwater use in African drylands. Per case study lessons learned and recommended approaches are provided.

In IWRM intervention planning for semi-arid regions a local increase in available water resources is sought after, which can be found in the better use of excess runoff. A balance between water demand and water resources on community level is key and a prerequisite for implementing durable and inclusive interventions that last. The IWRM process starts with a strong knowledge base. In practice, however, the development of a good knowledge base is not simple. Challenges arise in collecting, processing, and mapping results. With hydrogeology, a 3D situation is translated to 2D maps. Socio-economic data are often stored based on administrative boundaries and need corrections for hydrological source-area delineation and seasonal and interannual variations. Population density and water demand change over seasons, following crop cycles and livestock migration patterns. Looking at local water availability, rainfall and surface water flows are becoming more variable and less reliable. Therefore, assessment of the rainfall regime and corresponding behaviour and movements of people and livestock is key. For WIAs, yields and usage are often averaged, thus disregarding seasonal changes, even though shallow wells and reservoirs regularly become depleted outside the rainy season. The Sudan case study presents an improved approach for a WIA, that is adaptable and can be applied in semi-arid environments in Africa and elsewhere, in which seasonality and socio-economic dynamics were taken into account.

Both hydrogeologic and socio-economic conditions tend to be quite location-specific. This makes developing a simple blueprint for integrated groundwater management impossible. However, by translating local conditions into regional advice, strategic pathways were developed for the drylands of Africa[1] to support IWRM. The zonal hydrogeological and socio-economic setting determined the main groundwater issues and the potential sustainability strategies. The sustainability pathways describe potential sets of strategies that can be effective in moving towards sustainable groundwater resources development and use. While these pathways provide insight into regional differences within the African drylands, these cannot be used at local scales. Tailor-made approaches are necessary. In these assessments, remote sensing provides opportunities. Gridded datasets of population density are of great value in water demand assessments on a larger scale. Participatory stakeholder processes also provide opportunities, including group interviews for development of community calendars providing useful information on the occurrence and frequency of natural hazards and water demand.

[1] Gevaert et al. 2020, Towards sustainable groundwater use in the African drylands