Comparative Study of the International Law related to Water Sharing in Trans-boundary Rivers

As water resources become scarcer, trans-boundary water conflicts between countries located in the shared basins are increasing in frequency and intensity. The main challenge in these conflicts, especially in the arid and semi-arid regions of the world, is water sharing. The relevant international law and rules for trans-boundary waters include the Helsinki Rules, the UNECE Water Convention, the UN Watercourse Convention and the Berlin Rules. A brief review of research studies indicates that this set of documents has not been compared comprehensively taking into consideration water use provisions for implementation in the region. In this paper, the historical background, provisions and commentaries of the aforementioned documents as well as their strengths and weakness have been analytically discussed. The comparative study confirms that both important principles of “equitable and reasonable participation” and “obligation not to cause significant harm” have been considered in all of the relevant instruments and the results show that the 1997 UN Watercourse Convention is the most appropriate and equitable alternative for implementation in the region, including in Iran.