Seminar report on transboundary aquifers and international law: the experience of the Guarani aquifer system, University of Surrey, Guildford, UK, 31 August 2010

The world is currently facing a global water security challenge. Some regions are suffering water shortages, while others may have plentiful amounts of water, which is often of a contaminated nature. Competition over scarce water resources may lead to conflict between users, uses and communities that rely on that water, but may also lead to cooperation through the establishment of joint management strategies. Within this picture, a staggering 97% of globally available fresh water resources are stored underground and often cross borders. Until now, 273 transboundary aquifers have been identified under the UNESCO Internationally Shared Aquifer Resource Management (ISARM) programme. The Guarani Aquifer System (GAS) is just one of these transboundary aquifers, but amongst the most important for its size and quality of its waters. The GAS is shared by Argentina, Brazil, Paraguay and Uruguay; it stretches for 1,087,879 km2. An estimated population of 70 million people live in the GAS region, and economic development, and related water usages, is constantly increasing. The water quality is very good and there seem to be only minor problems of contamination and over-exploitation throughout the region. The importance of groundwater in the context of global water security should suggest the importance of groundwater management when an aquifer is shared by two or more countries, as is the case in the GAS. While some argue that rules devised for surface water management and regulation can also apply for groundwater, the international community has acknowledged that these rules had to be complemented by specific ones tailored to the hydro-geological characteristics of aquifers. The United Nations International Law Commission (UNILC), in collaboration with a multidisciplinary team led by the UNESCO International Hydrological Programme (IHP), has dealt with the law of transboundary aquifers from 2002 to 2008. This work has led to the adoption of a set of Draft Articles on the law of transboundary aquifers, which have now been annexed to the UN General Assembly Resolution 63/124.