This volume analyzes past, current, and future conditions in ten river basins from six continents, each located in arid or semi-arid climates, equipped with engineered dams designed to increase year-round water availability for irrigated agriculture, cities, and environmental flow; and each important for world food production and basin economies. This introductory chapter details the history of the inquiry and the research project. In the Challenge section of the book, we ask how water supply and demand are changing as a result of climate change, reservoir sedimentation, depletion of groundwater, and declining environmental flows. We then present case studies of each of the selected rivers: How do they recognize challenges and how do they deal with them? In the Response section, we discuss three important options for improved water management: water-wise irrigated agriculture, carefully designed inter-basin water transfers, and strong stakeholder participation.

The multi-year research effort in this volume has demonstrated that (1) similar challenges are faced by all SERIDAS rivers, (2) problem recognition varies widely across basins, and (3) response strategies are not sufficiently grounded in the long-term goal of river sustainability. We recommend that river managers and stakeholders follow these guidelines: Determine the river’s dependable yield – the water supply, averaged over the period of the most severe drought experienced in the historical record. Use the dependable yield to define and implement a river management strategy that carefully balances human and ecological needs in the basin. To meet human needs, do more with less – practice water conservation. This is the best obtainable strategy for redefining and maintaining river sustainability.

This chapter reviews the role of irrigation districts, city water utilities, and environmental groups in basin management. Examples from two river basins – Rio Grande and Euphrates–Tigris – illustrate vast differences in stakeholder participation. The authors recommend that all SERIDAS rivers pay increased attention to this option for better management. The four options for creating sub-basin water councils recommended for the Rio Grande provide useful guidance. Other models, reflecting different basin conditions, may emerge. Whatever model is selected, stakeholders should always organize to address the water agenda of their sub-basin. Doing so directly contributes to reaching and maintaining sustainability of the river as a whole.

The Rio Grande marks the border between the United States and Mexico, which makes its management particularly complex. A century of engineering and binational governance has shaped the region; today there are multiple reservoirs, diversion channels, and irrigation canals. International and national river managers consider challenges from reservoir sedimentation, population growth, and land use change. Climate change, on the other hand, is barely addressed. Managers must plan for a Rio Grande that by mid-century will have lost 40–50 percent of current water levels. Urban population will have doubled. Irrigated agriculture and cities will continue to use the bulk of available water. The most promising response to meet human and ecological water needs with reduced dependable yield is conservation. To address water scarcity, IBWC/CILA should develop a sustainability plan that balances reduced dependable yield with human and ecological needs. Progress should be reviewed and necessary changes to water allocations be negotiated at 5-year intervals. Irrigation districts, municipal utilities, and environmental stakeholders should work with IBWC/CILA to develop drought management for their sub-basins.

One of the most important topics for the twenty-first Century is sustainable development – development that meets the needs of the present without foreclosing the needs and options of future generations. Sustainable development is a comprehensive concept involving many disciplines, giving it both a philosophical base and a pragmatic approach. It appeals to a wide range of interests from nations to corporations to stakeholders because it combines economic development and environmental protection into a single system.

As the global community enters into the next phase of the evolution of sustainable development, making the transition from theory to action will be the next great challenge. World population is expected to double within the next 50 years, placing enormous demands on resources for food, shelter, and energy. Innovative solutions, incorporating the concepts of sustainable development, must be developed and implemented to mitigate these impending economic and environmental uncertainties and to guide society through the resulting period of transition. Examining this shift from theory to action and developing a plan of action was the framework of the De Lange♦Woodlands Conference, which was held March 3–5, 1997 in the Alice Pratt Brown Hall at Rice University in Houston, Texas.

The conference was organized by the Energy and Environmental Systems Institute at Rice University and the Center for Global Studies at the Houston Advanced Research Center in The Woodlands, in partnership with the National Academy of Sciences and the James A. Baker III Institute for Public Policy at Rice University.

Is development, as we know it, unsustainable? If so, can it be made sustainable? Can regions, nations, and the world as a whole reach a durable balance between economic, social, and environmental priorities? As we prepare for the twenty-first century, what role in reaching this goal can be played by the market and what must the state do? These are central questions in the debate on sustainable development. They are addressed, directly or indirectly, in most of the preceding chapters. Different answers emerge. I will attempt to summarize them in two contrasting views, one radical, the other incremental.

The radical view argues that sustainable development must be development without quantitative growth, the opposite of development as we know it. Why is radical change needed? Because business as usual will exhaust natural resources, overload the carrying capacity of natural systems, land, air, and oceans, and eventually lead to the collapse of human societies worldwide. The superbly successful engine that drove development since the beginning of the industrial revolution more than two centuries ago now carries in it the seeds of destruction. Maximizing income, profit and consumption are becoming counter-productive. Living in a full world the same way we lived in an empty world will be suicidal.

The radical perspective believes that sustainable development can prevent this outcome. It offers a prudent alternative to self-destruction. It does so by respecting the needs of coming generations, balancing economic with environmental concerns, reducing consumption in rich countries, and alleviating poverty in poor countries. These measures, once widely implemented, will guarantee the survival of the species.