At present 366 Transboundary Aquifers (TBAs) and 226 Transboundary Groundwater Bodies - as defined in the European Union Water Framework Directive - have been delineated (IGRAC and UNESCO-IHP, 2015). Progress in research and efforts towards joint management of Transboundary aquifers are steadily increasing, although there are still few TBAs which have been studied in detail or which are covered by some form of international agreement.
With increasing pressure on water resources in general, the often little or even unexploited resources of TBAs will become more important to basic human needs and socio-economic developments. Nijsten et al. (2018) highlighted that in Africa alone the currently known 72 TBAs underlie about 40% of the continent and that about 33% of the African population lives in these areas, which in the case of Africa are often also located in arid or semi-arid regions with high dependence on groundwater. It also appears that most of these TBAs are in areas of high storage and higher yielding aquifers, which indicates that the amount of groundwater stored within these TBAs is thus of importance for the development of Africa.
To highlight the (potential) importance of TBAs worldwide, IGRAC now compiled similar statistics for all continents with TBAs (see table 1). The analysis indicates that in particular in Africa and South America, TBAs cover substantial parts of the continents (approx. 40% and 39% respectively) and percentage of population living in these areas is also significant (approx. 30% and 21%). It isn’t a surprise that numbers are lower for North America as the United States of America and Canada already make up 88% of the surface area of the North American continent, which means that there is less ‘chance’ of TBAs occurring. Asia takes an intermediary position with the TWAP TBAs covering about 13% of the surface area of Asia and about 17% of the population living in these areas. For Europe the numbers are not representative as only 8 TBAs were covered in TWAP (see notes of caution in this brief). Overall the analysis confirms what Nijsten et.al. (2018) already indicated for Africa that TBAs are potentially of importance to a significant proportion of the world’s population.
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The full publication is available for download. When using this publication, please use this preferred citation: IGRAC (2018) Population and areal statistics for 199 Transboundary Aquifers. Delft: IGRAC.