Intensive use of groundwater in transboundary aquifers

Transboundary aquifers are present in all parts of the world, ranging from hundreds to tens of thousands km 2 . The largest have fresh water to provide the planets drinking water needs for 200 years, e.g. the Guarani. Intensive use of most of the larger transboundary aquifers has not yet taken place. Consequently, in broad terms they are not yet severely threatened, though with conspicuous exceptions e.g. the Middle East. Some smaller, and therefore more vulnerable transboundary aquifers are intensively used. Severe overabstraction is still contained within national boundaries, but continuing demands could impact across national boundaries especially in arid zones. For the sustainable use and sound management, plans need to be made in early stages of development, with the participation of all the riparians, to ensure equitable and fair share. This chapter outlines a multi disciplinary approach, involving the legal, institutional, economic and environmental inputs, that is needed, over and above the hydrogeological understanding. Suggestions are made about the staged process, commencing from the status quo , quasi-steady state analysis.