Sub-Saharan Africa (SSA; Fig. 1) refers to an area encompassing the countries in Africa that are fully, or partially, located south of the Sahara. The remaining African countries are generally referred to as belonging in North Africa. Although the socio-economic and hydrogeological conditions in SSA are diverse, they are sufficiently distinct (in general) from the conditions in North Africa to warrant being assessed separately—for example, high-yielding, high-storage, sedimentary aquifers are more common in North Africa than in SSA, while low-yielding, low-storage, basement aquifers are more widespread in SSA than in North Africa. The use of fossil groundwater is more typical in North Africa, while the use or renewable groundwater is more typical in SSA. Other hydrological characteristics associated with SSA include: groundwater resources that are generally under-utilized; lack of research and development that often prevents the optimal use of groundwater rather than over-development; and a heavy reliance by the rural and urban poor on shallow unconfined or semi-confined groundwater for potable water supplies, other domestic uses, and subsistence agriculture. Because of distinguishing characteristics such as these, there are good reasons for treating the hydrogeology of SSA as a whole, and separate from North Africa.

Introduction
Sub-Saharan Africa (SSA; Fig. 1) refers to an area encompassing the countries in Africa that are fully, or partially, located south of the Sahara. The remaining African countries are generally referred to as belonging in North Africa. Although the socio-economic and hydrogeological conditions in SSA are diverse, they are sufficiently distinct (in general) from the conditions in North Africa to warrant being assessed separately—for example, high-yielding, high-storage, sedimentary aquifers are more common in North Africa than in SSA, while low-yielding, low-storage, basement aquifers are more widespread in SSA than in North Africa. The use of fossil groundwater is more typical in North Africa, while the use or renewable groundwater is more typical in SSA. Other hydrological characteristics associated with SSA include: groundwater resources that are generally under-utilized; lack of research and development that often prevents the optimal use of groundwater rather than over-development; and a heavy reliance by the rural and urban poor on shallow unconfined or semi-confined groundwater for potable water supplies, other domestic uses, and subsistence agriculture. Because of distinguishing characteristics such as these, there are good reasons for treating the hydrogeology of SSA as a whole, and separate from North Africa.