Aquifer systems constitute a substancia part of a country's available water resources, yet in some regions they are very incompletely known and understood. Aquifer systems, much more commonly than transboundary rivers, can be shared between several countries that generally use them in an independent and often intensive manner, for drinking-water supply, industry and in particular for irrigated agriculture. The often poorly managed use of such resources leads in many cases to groundwater mining and apollution, which in ture creates local tensions, and the risk of crises and conflicts between countries. The aim of the present methodological guidebook is to deepen our knowledge of such groundwater systems, fostering a collaborative, equitable and sustainable management of these resources. It first recalls the main issues at stake regarding transboundary aquifers and the need for a more comprehensive approcah based on IWRM principles (Part I). It then describes some existing tools that can help in improving our knowledge and management of these precious resources; this includes technical, legal, organizational and economic tools, as well as training and cooperation tools (Part II). Finally, it proposes a progressive, multi-pronged approach for implementing the collaborative, equitable and sustainable management of transboundary aquifer systems. It also takes a look at hte potential mechanisms for creating and sustainably operating an appropriate institutional structure to manage these shared groundwater resources (Part III).

(SHORT VERSION) This article explores the role of hydrogeology in the emergence of management policies for the Guaraní Aquifer system, a vast transboundary groundwater reservoir shared by Argentina, Brazil, Paraguay, and Uruguay. It finds that the emergence of knowledge about the resources, which came concomitant with processes of democratization in the region and the constitution of new knowledge networks, fostered the political process that ultimately led to the implementation of joint management policies for the transboundary groundwaters.

This book focuses on sustainable use and protection of transboundary aquifers located along the eastern border of European Union starting from the Baltic Sea and end in the Black Sea. The groundwater resources in this region play a very important role not only as a source of clean and safe drinking water, but also for social, economic and safety reasons. This publication sheds light on a wide range of real problems related to the management of groundwater, problems that are characteristic for most countries situated in the East European region. It also identifies potential threats that may materialise in the absence of cooperation between countries and appropriate measures to jointly manage the shared water resources in the region. Experience from some ongoing projects towards integrated management of transboundary aquifers (research, monitoring and data analysis) is reported. The book is addressed, in particular, to groundwater academics, researchers and experts as well as water management specialists interested in solving environmental issues extended to more than one country territory. On the other hand presented knowledge and experience would be also useful for decision makers especially to support environmental decision processes in border areas and work on preparation of international agreements on groundwater management.

Transboundary aquifers are as important a component of global water resource systems as are transboundary rivers; yet, their recognition in international water policy and legislation is very limited. Existing international conventions and agreements barely address aquifers and their resources. To rectify this deficiency, the International Association of Hydrogeologists and UNESCO's International Hydrological Programme have established the Internationally Shared (transboundary) Aquifer Resource Management (ISARM) Programme. This multiagency cooperative program has launched a number of global and regional initiatives. These are designed to delineate and analyze transboundary aquifer systems and to encourage riparian states to work cooperatively toward mutually beneficial and sustainable aquifer development. The agencies participating in ISARM include international and regional organizations (e.g., Organization of American States, United Nations Environment Programme, United Nations Economic Commission for Europe, Food and Agriculture Organization, and South African Development Community). Using outputs of case studies, the ISARM Programme is building scientific, legal, environmental, socioeconomic, and institutional guidelines and recommendations to aid sharing nations in the management of their transboundary aquifers. Since its start in 2000, the program has completed inventories of transboundary aquifers in the Americas and Africa and several ISARM case studies have commenced.

Groundwater amounts to 97% of available global freshwater resources. Emphasising the crucial importance of this in the context of increasing population, climate change and the overall global water crisis, Francesco Sindico offers a comprehensive study of the emerging body of international law applicable to transboundary aquifers.

Groundwater is invisible, but its impact is visible everywhere. Everything around us relies on groundwater, our drinking water and sanitation, our food supply and our natural environment. Yet because it is invisible, information, management and governance of groundwater is often poor and inadequate. This book contributes to UN Water Groundwater year (2022), and to the effort of “making the invisible, visible”. Through worldwide case studies ranging from the Americas (California, Brazil), to Asia (India, Iran, Lao PDR, Nepal), Africa (Malawi, Tanzania, South Africa) and the MENA region (Lebanon, Morocco, Yemen), including cases of transboundary aquifers, the chapters in this edited volume reflect important recent advances in interdisciplinary knowledge on the governance, management, practice and science-policy interfaces of groundwater. An insightful resource for researchers and planners in the field of environmental policies, water laws, climate change and groundwater governance, this book comes with a new Introduction. The other chapters were originally published in Water International.