Could Turkey dam the Tigris and Euphrates and deprive its downstream neighbors of vital water resources? Could Brazil over-pump the Guarani Aquifer System to the detriment of the other aquifer states? Could Egypt put pressure on upstream Nile states and prevent them from developing river related infrastructure that might limit downstream flow? International law in the field of transboundary water cooperation has evolved and would appear to condemn unilateral practices such as the ones suggested above. However, hydro politics and the lack of reception of international water law instruments by many countries sometimes make it difficult to see international law properly reflected in the management of major rivers, lakes and aquifers around the world. In this essay, I first highlight what international law dictates when it comes to the tension between national sovereignty and transboundary water cooperation. I then explore how this tension plays out in the three examples noted above. Due to limited acceptance of the existing international, bilateral, or regional legal instruments, the resolution of the tension between national sovereignty and transboundary water cooperation will often be left to customary international law.
Measuring transboundary water cooperation: learning from the past to inform the sustainable development goals
