Mapping of groundwater potential zones in the drought-prone areas of south Madagascar using geospatial techniques

Abstract

The southern regions of Madagascar have the country’s lowest water supply coverage and are highly vulnerable to drought. Access to potable drinking water is a major challenge for the local population. Chronic droughts lead to annual emergency appeals to save the lives of acute malnourished children. UNICEF’s response consisting in providing potable drinking water through the drilling of boreholes has been challenged by the complex hydrogeology, the low yield of boreholes and high-level salinity of water, the lack of reliable groundwater data and the weak capacity of the drilling sector. These constraints result in a high rate of drilling failure. To improve drilling success and provide more potable drinking water to local communities, it is vital to undertake reliable groundwater investigation.UNICEF Madagascar and the European Union delegation in Madagascar collaborated on the use of satellite imagery to improve sector knowledge and access to safe and clean water for local communities in southern Madagascar. The methodology relies on produce thematic layers of groundwater potential areas. Later, these thematic layers were overlaid with ground-based hydrogeological data to map the groundwater potential zones (GWP) and identify the most suitable sites for borehole siting and drilling. Findings of this study are very encouraging, and the integrated approach used has proven its applicability in mapping groundwater potential areas in the eight drought-affected areas of south Madagascar. The groundwater potential zone map is being used by UNICEF and partners to plan water supply projects and identify the best sites for positioning new boreholes and reduce the likelihood of drilling failure. Additionally, the project developed a database of groundwater resources, which will improve knowledge of the regional hydrogeological context and strengthen the capacity of the water sector. Lessons learnt from this study show that an integration of the groundwater potential zone map with demographics and water demand information will help identifying priority areas for detailed studies. Moreover, a capacity building activity is required for knowledge/technology transfer to the Ministry of Energy, Water and Hydrocarbons (MEEH), allowing the possibility of scaling-up this integrated approach to the rest of Madagascar. Finally, strengthening the capacity of the MEEH and refining this approach as suggested above will certainly help in the pursuit to improve equitable access to safe and clean water for households located in the drought-affected areas of southern Madagascar, allowing them to be more resilient to the effects of climate change.