Such relief was not always effective, however, and in many cases resources were poorly targeted, or arrived too late. The response of groundwater to drought Because aquifers take some time to react to changes in rainfall, groundwater sources can bridge surface water deficits. The disadvantage is that groundwater also recovers more slowly after drought than surface water. Since 1994, BGS have been working with partners in Ghana, Malawi and South Africa on groundwater management strategies for drought-prone areas. A key contention of the work is that some groundwater sources, and some areas, are much more sensitive to groundwater drought than others.
Sensitivity depends on a number of physical, technical and socio-economic factors.
By combining them, in the form maps, we can identify areas at particular risk. The maps combine indices of groundwater availability with supply coverage and water demand. Together, these factors indicate, at a broad scale those areas most at risk to groundwater drought. Maps can be used to target monitoring programmes, inform technical choices, and target well deepening and rehabilitation programmes in pre-drought periods, reducing the need for drought relief. One important application, now the subject of a new research project, is the identification of critical monitoring zones.