Resource economics and development.

Recent research includes a study of water markets and the transaction costs of sectoral and intersectoral water exchanges, an economic analysis of agricultural pollution of groundwater, a study of the transaction costs of alternative methods for providing urban water supplies in developing countries, and an evaluation of the secondary economic impacts of interbasin water transfers.

During 1991-93 he worked with the World Bank and was senior author of their Water Resources Management Policy. Other published works include numerous articles in journals such as Water Resource Research, Water Resources Bulletin, American Journal of Agricultural Economics and Land Economics, and ten books on water resources management and research.