The way water scarcity issues are addressed impacts upon the achievement of most of the Millennium Development Goals. The increasing significance of water scarcity worldwide calls for increased integration and cooperation to ensure sustainable, efficient and equitable management of scarce water resources, both at international, regional, and local levels. Cooperating on transboundary river and aquifer water uses and optimal allocation of water resources is an important element of water diplomacy. This focal area, therefore promotes catchment-based water resources planning and decision-making, rational allocation of water resources and regulation of water use, and conjunctive use of groundwater and surface water.