The interplay between the UN Watercourses Convention and the Law on Transboundary Aquifers (Article 2)

Transboundary aquifers play a substantial role in global water security. Groundwater is estimated to represent 97% of the available freshwater on the planet and has significant importance in terms of human and ecosystem water supply. An estimated 2.5 billion people depend solely on groundwater resources to satisfy their basic needs. Further, groundwater provides drinking water to more than half of the global population and supplies 43% of the water used for irrigation . Groundwater can be found in an aquifer, which is “a permeable water-bearing geological formation underlain by a less permeable layer”. Aquifers are considered transboundary when parts of them are situated in different states, and almost 600 transboundary aquifers and groundwater bodies have been identified so far. For the purposes of this chapter, the ‘law of transboundary aquifers’ refers to the sparsely populated set of international legal instruments governing transboundary aquifers. We will focus primarily on the 2008 Draft Articles on the Law of Transboundary Aquifers (Draft Articles), which, together with the UN Watercourses Convention (UNWC), comprises the guidance issued by the International Law Commission (ILC) with respect to transboundary water resources. The law of transboundary aquifers also includes the UNECE Convention on the Protection and Use of Transboundary Watercourses and International Lakes (UNECE Water Convention), the UNECE Model Provisions on Transboundary Groundwater, a handful of bilateral and multilateral agreements addressing specific transboundary aquifers, and several non-governmental efforts in the field of transboundary aquifers. Against this background, in this chapter we will examine how groundwater has been tackled in the works leading to the UNWC and in the UNWC itself. Then we will study the Draft Articles and their relation to the UNWC. Finally, we will explore a normative package approach to the UNWC and the law of transboundary aquifers