More than half of the world’s population depends daily upon water resources shared by more than one country, both surface water of transboundary rivers and lakes or groundwater contained in aquifers extending over several countries. As the needs for this precious resource continue to increase, the imperative for cooperation between countries for better managing this resource has never been greater.

How we agree to share the beneficial uses of transboundary water resources in ways that meet economic, social, and environmental demands in terms of growing uncertainty and financial instability might be one of the greatest challenges of all.

Population growth, expanding urbanization, the development of industry, agriculture, tourism as well as changes in climate and lifestyle, including in food and eating habits, place increasing constraints on water resources and ecosystems. New means are required to better manage this resource at every possible scale; especially in the highly complex situation of transboundary waters.

The integrated approach to water resources management (IWRM) that many countries have introduced into their national policies must also be the backbone of transboundary basin management. The catchment area of a river, lake and aquifer is indeed the space where hydrological, social, economic and environmental interdependences appear and where integrated development and management of water resources and territories have the potential to yield the greatest success.

Building a global community across transboundary waters that enhances connections between all stakeholders is an important undertaking that justifies increased investment and attention, to ensure ‘water for all’. Achieving the equitable, reasonable and sustainable use of the world’s shared water resources, and moving us all towards increased water security are aims that must be pursued fully.

To support this process, the International Network of Basin Organizations (INBO), the Global Water Partnership (GWP), UNECE, UNESCO, GEF, EVREN and AFD have worked together to produce this Handbook.

This collective work provides relevant and practical information that can assist with the improved integrated management of the world’s shared transboundary water resources.

This Handbook addresses a large number of stakeholders involved in integrated management of transboundary water resources, from national governments to regional organizations, managers and users in the field. They all are invited to work together to face the many current and future challenges.

The Handbook offers guidance for the integrated management of transboundary water resources in all of its diversity – for developing and developed countries, in temperate, wet or dry areas.

This new work supplements the Handbook for Integrated Water Resources Management in Basins, published in March 2009 during the Fifth World Water Forum in Istanbul.