Water Policy 4 (2002) 19–32 Towards measurable criteria for the equitable sharing of international water resources Pieter van der Zaag*, I.M. Seyam, Hubert H.G. Savenije IHE Delft, P.O. Box 3015, 2601 DA Delft, The Netherlands Received 18 February 2001; received in revised form 11 September 2001; accepted 16 December 2001 Abstract Equity is key to the allocation of international water resources. Six possible criteria and allocation algorithms that operationalise the equity concept, are developed and applied to the Orange, Nile and Incomati rivers. The criterion that considers all (blue and green) water resources and that uses the basin population as the main allocation variable yields the most equitable water allocation. Two important variables are identified over which the riparian countries should reach consensus: 1. The value of green water relative to blue water. 2. The fraction of reserved water, which is defined as the basic entitlement of each riparian country. These findings are based on approximate data and have therefore a limited validity. With this caveat it is suggested that the approach developed in this article may help de-politicise negotiations between riparian countries and provide fresh perspectives that may unlock stalemates during negotiations. r 2002 Elsevier Science Ltd. All rights reserved. Keywords: Allocation algorithms; Equity; Green water; Incomati river; International water resources; Nile river; Orange river; Water allocation; Water law 1. Introduction The United Nations Convention on the Law of the Non-Navigational Uses of International Watercourses, adopted by the General Assembly in 1997, provides a framework for negotiations between countries sharing an international water resource. The convention defines the obligation *Corresponding author. IHE Delft, PO Box MP 600, Mount Pleasant, Harare, Zimbabwe. Tel.: +263-4-336-725; fax: +263-4-336-740. E-mail address: ihe@mango.zw (P. van der Zaag). 1366-7017/02/$-see front matter r 2002 Elsevier Science Ltd. All rights reserved. PII:S1366-7017(02)00003-X