New criteria to assess interbasin water transfers and a case for Nzoia-Suam/Turkwel in Kenya

Abstract

Although an interbasin water transfer project (IWT) is subject to many issues ranging from socio-economic to ecological, the final decision on implementation is always a political one, made in the best interest of sitting administrations. Therefore a sound pragmatic assessment process for IWTs should be used to inform the final (political) decision. Unfortunately, there is no universally agreed set of criteria for assessment of IWTs. Existing criteria vary and tend to be prescriptive and subjective. In addition, the assessment is often further complicated by paucity of data and transboundary issues. This paper proposes an evaluation approach that guarantees internal objectivity for specific projects. It is based on three basic requirements, firstly, the need to objectively justify the project, secondly, the need to show that the adverse effects of the project are minimized, and thirdly, the need to show that the expected benefits are maximized. Assessment of the sustainability of a project is made by tree-branching the three basic requirements and assigning an equal weight, a positive or a negative mark, to sub-branches at the highest branch level reached. A positive mark is given for an issue deemed to favour implementation of a project, or otherwise a negative mark. The final score for decision making is the percentage of the positive marks to the total marks. This method is demonstrated on a proposed IWT from the water-rich Nzoia River basin to the existing Turkwel Gorge Reservoir in the water-deficit Suam/Turkwel River basin, both in Kenya but having international issues.