Colleagues and friends of Dan Yaron submitted the following tributes. While each submission comes from an individual who knew Dan in a very different way, they all remark on his immeasurable contributions to the field of agricultural eco nomics, his unique approach, which combines his training and experience with his scientific background, and the admirable professionalism and civility that was apparent in every project he undertook. His work, initially inspired by the chal lenge of farmers in the arid Negev, eventually took him to the United States to work with universities and to serve on commissions furnishing his research with global applicability. Dan is not only admired for his enormous contributions to the vast body of research available in his field, but also for the commitment and dedi cation he epitomized. He will be greatly missed by those of us who were fortunate enough to make his acquaintance. ELIFEINERMAN The Hebrew University of Jerusalem, Rehovot, Israel Dan Yaron, my teacher and mentor of blessed memory, was a man of wisdom, thought, counsel and deeds. His many talents, his endless energy and his ambition led him to blaze new trails in research, to ask the relevant questions while separat ing the wheat from the chaff, and to answer them while mastering the most ad vanced scientific analyses.

In December 2002, a group of specialists on water resources from the United States and Iran met in Tunis, Tunisia, for an interacademy workshop on water resources management, conservation, and recycling. This was the fourth interacademy workshop on a variety of topics held in 2002, the first year of such workshops. Tunis was selected as the location for the workshop because the Tunisian experience in addressing water conservation issues was of interest to the participants from both the United States and Iran. This report includes the agenda for the workshop, all of the papers that were presented, and the list of site visits.

There has been a recent explosion of research incorporating a spatial dimension in environmental and natural resource economics, where the spatial aspects of human behaviour or the natural environment make a crucial difference in the analysis and policy response to the problem. Much of this research has been driven by the growing availability of spatially explicit social science data and the development of tools and methodological advances to use these data. Collected in this volume are 24 key articles considering the reasons for spatial variation in policies, due to either efficiency or equity considerations, and the consequences of that spatial variation for both environmental and economic outcomes. These articles demonstrate that the failure to address spatial issues in the analysis can create two problems: (1) the analysis provides a poor basis for predicting actual behaviour that is specifically based upon spatial considerations, and (2) the analysis fails to provide a basis for designing spatially targeted policies that could lead to more efficient outcomes.

In order to deal with the water scarcity problem, public and private sectors have made tremendous efforts worldwide. China is facing severe water shortage due to climatic, geographical and demographic factors. Especially, inefficient management and under-developed water conservation technology in agricultural sector are big problems for the government and farmers. The book provides theoretical and quantitative tools to manage water resource and irrigation projects efficiently. Meanwhile farmers' choices of modern irrigation technology are taken into account to evaluate on-farm water efficiency. The study investigates the impact of public and private investment on water resources allocation and social welfare in an irrigation area using a spatial mathematical programming model. The results of the study show that aggregate water efficiency in an irrigation area will be improved significantly by increasing public and private investment in water conservation activities.

Water is becoming an increasingly scarce commodity in many parts of the world. Population growth plus a growing appetite for larger quantities of cheap water quality as a result of urban, industrial, and agricultural pollution coupled with increasing environmental demands have further reduced usable suppliers. This book brings together thirty of the best economic articles addressing water scarcity issues within the US and Mexico. By touching on a number of different issues, this volume clearly articulates the need for improving existing institutional arrangements as well as for developing new arrangements to address growing water scarcity problems.