Degraded water quality, physical and economic water scarcity, and loss of freshwater ecosystem services have significant impacts on human safety and security. Floods and droughts affect ever-larger numbers of vulnerable people (IPCC 2014), with security and migration implications magnified in transboundary basins.
Transboundary cooperation in addressing water scarcity, floods and droughts is challenging, but can enable more effective, efficient management and adaptation by pooling available data, models, scenarios and resources, and enlarging the planning space for locating adaptation measures, including transboundary basins (United Nations Economic Commission for Europe and International Network of Basin Organizations 2015). Transboundary water management creates benefits in international trade, climate change adaptation, economic growth, food security, and improved governance and regional integration.
About 286 international transboundary river basins involving 151 countries pose challenging management problems (UNEP-DHI Partnership and UNEP 2016), as do transboundary lakes and reservoirs. Further, there are currently 366 identified transboundary aquifers and 226 transboundary ‘groundwater bodies’ underlying almost every nation (International Groundwater Resources Assessment Centre and United Nations Educational Scientific and Cultural Organization - International Hydrological Programme 2015). Even within federated countries (e.g. Australia, India, the United States of America), transboundary problems may be no less acute at a state/provincial level. Although water management has historically led to cooperative, rather than conflicting, outcomes, significant conflicts between stakeholders can still occur over the implementation of international and inter-state agreements. Intensification of water pollution and water scarcity can cause tensions within and between nations, though rarely being the sole trigger of conflict, since a complex mix of social and political conflicts, economic, demographic and environmental factors, and military occupation and water wars (hegemony) is typically the origin of such conflicts.