Alena Drieschova. Mark GiordanoB
The issue of equity has been described as the heart of transboundary water law. But equity in transboundary water sharing and management depends on the availability of inherently variable water supplies. The historic record has already shown that failure to properly consider flow variability within transboundary agreements can lead to increased levels of tension between co-riparian states once flow levels diverge from "normal". There is now also evidence that climate change will further increase variability of flows, increasing the probability of both low and high flow events which fall outside the bounds of existing institutional designs. Despite the current and growing importance of variability in international water diplomacy, no systematic analyses have been carried out to examine either the extent to which flow variability has been addressed in transboundary water law or the range of mechanisms that have been employed by riparian states to mitigate the potentially negative impacts of unexpected changes in transboundary water availability. This paper partially fills these knowledge gaps by analysing the commonality of flow variability mechanisms in 50 treaties written over the last quarter century. It was found that flow variability can be and has been governed using a variety of mechanisms. While some mechanisms explicitly address variability, the majority use more subtle, open-ended approaches for water regulation. In addition, most of the mechanisms adopted deviate from the 'ideal' state of being both flexible in the face of change but binding in enforcement. Instead, the mechanisms adopted reflect a trade-off between flexibility and enforcement. The results are used to develop a model for considering strategies in transboundary water law formation which are both politically feasible and mitigate the impacts of variability on riparian relations.