10.2190/7NM4-YL14-808F-84KG 7NM4YL14808F84KG 1 Environmental Project Reevaluation with Rising Calendar Time Benefits 167 175 20020509 20020509 20020509 20020509 7NM4YL14808F84KG.pdf http://baywood.metapress.com/link.asp?target=contribution&id=7NM4YL14808F84KG 3 David C. Major Branden B. Johnson Robert H. Cole Richard Hosier Murdo Morrison Clark University, Worcester, Massachusetts Michigan Technological University, Houghton, Michigan Life Systems, Cleveland, Ohio University of Pennsylvania, Philadelphia, Pennsylvania Prudential Insurance Company, Auburn, Massachusetts This article examines one aspect of the dynamic analysis of environmental systems, the effects of rising calendar time benefits on project reevaluation and scheduling. The effects of rising calendar time benefits, an aspect of what is known as the optimal scheduling criterion, are assessed here in terms of a water resource project, the Hangang barrage and hydropower unit in Korea. The rising calendar time benefits used in the reevaluation are those resulting from the rise in real fuel prices that occurred following the completion of the plan. When these benefits are used in the reevaluation of the hydropower unit, this previously rejected project increment becomes justified; its optimal scheduling depends on its degree of separability and the existence of calendar time effects other than those studied. The results suggest the importance in environmental systems analysis of not modelling a system on the convenient assumption that key benefit and cost parameter values will remain constant over time. United States Department of the Interior, Bureau of Reclamation and Geological Survey, in cooperation with the Republic of Korea, Ministry of Construction, Korean Water Resources Development Cooperation, <i>Reconnaisance Report Water Resources Study: Han River Basin</i>, summary and 3 volumes, 1971. D. C. Major, <i>Multiobjective Water Resource Planning</i>, American Geophysical Union, Washington, D. C., 1977. S. A. Marglin, <i>Approaches to Dynamic Investment Planning</i>, North-Holland, Amsterdam, 1963. A. Maass, et al., <i>Design of Water-Resource Systems</i>, Harvard University Press, Cambridge, MA, 1962. S. A. Marglin, <i>Public Investment Criteria</i>, MIT Press, Cambridge, MA, 1967. United States Water Resources Council, Water and Related Land Resources: Establishment of Principles and Standards for Planning, <i>Federal Register, 38</i>:174, pp. 24778-24869, 1973. Republic of Korea, Four Major River Basin Development Committee, <i>Integrated Development Plan for Four Major River Basins</i>, Seoul, December 1970. United States Department of Energy, Energy Information Administration, <i>Annual Report to Congress, Vol. 3</i>, Washington, D. C., 1980.