Introduction : the debate on climate change and water security -- Theory of scarcity-variability, conflict, and cooperation -- Emergence of cooperation under scarcity and variability -- Institutions and the stability of cooperative arrangements under scarcity and variability -- Incentives to cooperate : political and economic instruments -- Evidence-how do basin riparian countries cope with water scarcity and variability -- Conclusion and policy implications

The 21st century will witness the collision of two powerful forces - burgeoning population growth, together with a changing climate. With population growth, water scarcity will proliferate to new areas across the globe. And with climate change, rainfall will become more fickle, with longer and deeper periods of droughts and deluges. This report presents new evidence to advance understanding on how rainfall shocks coupled with water scarcity, impacts farms, firms, and families. On farms, the largest consumers of water in the world, impacts are channeled from declining yields to changing landscapes. In cities, water extremes especially when combined with unreliable infrastructure can stall firm production, sales, and revenue. At the center of this are families, who feel the impacts of this uncertainty on their incomes, jobs, and long-term health and welfare. Although a rainfall shock may be fleeting, its consequences can become permanent and shape the destiny of those who experience it. Pursuing business as usual will lead many countries down a 'parched path' where droughts shape destinies. Avoiding this misery in slow motion will call for fundamental changes to water policy around the globe. Building resilience to rainfall variability will require using different policy instruments to address the multifaceted nature of water. A key message of this report is that water has multiple economic attributes, each of which entail distinct policy responses. If water is not managed more prudently--from source, to tap, and back to source--the crises observed today will become the catastrophes of tomorrow.

The 21st century will witness the collision of two powerful forces -- burgeoning population growth, together with a changing climate. With population growth, water scarcity will proliferate to new areas across the globe. And with climate change, rainfall will become more fickle, with longer and deeper periods of droughts and deluges. This report presents new evidence to advance understanding on how rainfall shocks coupled with water scarcity, impacts farms, firms, and families.

This Book includes selected papers that has been published in the Water journal Special Issue (SI) on Water Supply and Water Scarcity. Moreover, an overview of the SI is included. The papers selected for publication in the SI include review and research papers on water history, on water management issues under water scarcity regimes, on rainwater harvesting, on water quality and degradation, and on climatic variability impacts on water resources. Overall, the issue identify and highlight the main challenges in water sector, and particularly in management and protection of water resources and in use of alternative (non-conventional) water resources, especially in areas with demographic change and climate vulnerability in order to achieve sustainable and secure water supply. Furthermore, general guidelines and possible solutions for an improved and sophisticated water management system are proposed and discussed, such as the adoption of advanced technological solutions and practices that improve water-use efficiency and the use of alternative water resources, to address the growing environmental and health issues and to reduce the emerging conflicts among water users.

This volume includes over 30 chapters, written by experts from around the world. It examines the environmental aspects of drought such as groundwater and soil contamination, river low-flow, urban water quality, and desertification. It also examines the effects of climate change and variability on drought, and discusses the differences in groundwater, rainfall, and temperatures and their related effects. It presents analytical modeling for better understanding drought in uncertain and changing climates.

Water scarcity due to climate change, population growth, and economic development is a critical issue in many semi-arid and arid regions around the world. Water scarcity is especially critical in regions where water is shared by several riparian states and used for competing purposes (irrigation, domestic, industry, environment, and hydropower). There is evidence that water scarcity may give rise to conflicts among the riparian states that share water basins. At the same time, there is evidence that proper arrangements among riparian states create a basis for cooperation, which is a necessary condition for economic development, food production, environmental sustainability, and poverty reduction. This book presents a collection of work presented by a group of academics and policy experts dealing with the impact of water scarcity and variability on the ability to jointly manage shared water and the derived welfare of international states and nations sharing international river basins, consisting of economics, technology, law and institutions, geography, and international relations.The book covers theoretical aspects of management of transboundary water as well as case studies from hotspots around the world. The unique aspect of this book is the multidisciplinary nature of the chapters, reflecting a new field of research that will gain popularity as water scarcity will increase over time and across regions.The chapters from the book were presented at the 'Management of Transboundary Water Resources under Scarcity: Perspectives on Agriculture and Food Security' workshop held at The Hebrew University of Jerusalem, Israel, from June 22 to 23, 2015.

This paper assesses the impact of water supply variability on treaty cooperation between international bilateral river basin riparian states. Climate change is anticipated to change the variability of water supply, as well as its expected magnitude. Previous studies have focused mainly on water scarcity, measured in terms of mean precipitation or per capita water availability in the country, as a trigger for conflict or cooperation. The water variability measure used here captures both annual runoff variability and precipitation variability over periods of 30 and 100 years. The analysis used economic and international relations data to identify incentives for international cooperation in addressing water supply variability. The authors find that small-to-moderate increases in variability create an impetus for cooperation, although large increases in variability would reduce incentives for treaty cooperation. Stronger diplomatic and trade relations support cooperation, while uneven economic power inhibits cooperation. Various measures of democracy/governance suggest different impacts on cooperation across the basin riparians. The findings have policy implications in the context of preparedness for impacts of climate change on the water sector.