Climate change will stress both the consumptive and non-consumptive uses of transboundary watercourses. Existing hydrological models may be unreliable and expected supplies may diminish over time at the same time that extreme flood events become more frequent. Riparian countries must adopt more flexible management regimes to adapt to these stresses. International water law is not well suited to do so because it focuses on the creation of secure, long-term entitlements rather than on mechanisms to adjust entitlements to changed conditions and gives comparatively little weight to the conservation of aquatic ecosystems. International water law can promote adaptation by recognizing that the fundamental norm of reasonable and equitable use can incorporate adjustment to climate change. In addition, the evolving norm that riparian nations have an affirmative duty to cooperate in the management of transboundary watercourses can promote the incorporation of climate science and adaptive management into the use of these freshwater resources.
A Dan Tarlock
Climate change will exacerbate the problems in countries that experience the uneven distribution of water or face chronic risks of shortages. These countries may have to reform their water laws to provide clearer and fairer standards to allocate and distribute limited supplies. No country has yet comprehensively reformed its allocation laws to adapt to climate change, but existing laws can be adapted to this purpose. Countries have long asserted the power to set the ground rules for the acquisition and enjoyment of water entitlements. This power enables countries to adapt their existing shortage allocation and distribution laws to climate change.
Lakshman Guruswamy and A. Dan Tarlock
Rhett Larson and A. Dan Tarlock
Many countries with federal systems have decades or centuries of experience managing water that traverses sub-national jurisdictional boundaries. Australia, Brazil, Canada, China, Germany, India and the United States of America have developed transboundary water laws to address or avoid inter-jurisdictional water disputes between subsidiary states or provinces. Practitioners and scholars of international water law can draw lessons from these countries’ experience in managing transboundary waters. These countries have demonstrated success in managing transboundary waters which could be adapted to the international context, and each country has made mistakes in transboundary water governance which serve as cautionary tales for international water law. This chapter discusses the successes and failures of domestic federal systems in managing transboundary waters and suggests reforms for international water law based on those domestic lessons.