USING A GEOGRAPHIC INFORMATION SYSTEM TO ANALYZE THE EF­ FECTS OF SEA LEVEL RISEl

Mean sea level rise on the eastern seaboardhas been documentedover the last fifty years and may continue at an accelerated rate in the future if certain predictions con­ cerning the greenhouse effect prove correct. A geographic information system (ERDAS) was used in conjunction with satellite imagery to determine the affect on land use ofvarious sea level rise scenarios in a small portion of eastern Long Island. A general method for conducting such investigations was developed and the site specific problems of such an analysis were isolated. It was determined that a sea level rise ofone to five feet would have a significant impact, although coastal flooding would not be as severe as anticipated. The mean sea level as measured at Sandy Hook, New Jersey, has been rising for the last futy years at an approximate rate of 0.014 feet per year and is anticipated to con­ tinue to rise at the same rate for the indefmite future (Lyles et al. 1988, 72). This in­ crease in sea level is attributed to general geophysical factors acting on the eastern seaboard that are causing the coastal region to sink. and are not related to any increase in the volume of sea water in the Atlantic Ocean. Despite the lack of contemporary evidence for sea level rise induced by global warming, concern over this possibility is growing, encouraged by the debate over the inevitability or avoidability of the greenhouse effect and the consequences to be expected from it. The goal of this project was to perfonn an initial analysis ofthe effect of sea level rise on the portion of the Long Island coast in the vicinity of Mecox Bay using a geographic infonnation system (GIS) and a SPOT image. A general methodology for performing such analyses was to be developed, feasibility of economic valuations were to be deter­ mined, and technical problems were to be noted so that future efforts in this area can be more refmed. In addition, the project would yield insight into the general usefulness of the method and the limitations imposed by specific site conditions. As a fmal result of the analysis, an outline of economic, social, and topographical effects of sea level rise on the area would be determined. It was concluded that a GIS is an effective tool for studying the affect of sea level rise on selected areas, and that it is feasible to arrive at an assessment of projected effects. The technical problems associated with the task, in particular the registration of the SPOT image to the relevant map coordinates, were more difficult than anticipated, and the limits of the system's resolution, the accuracy of the land use classification, and ter­ rain digitizing, all required that adjustments to the process of analysis be made. Many of these were site-specific and can yield only general insights into the analysis process. Finally, the affect of sea level rise on the study area would be marked, although not as severe as anticipated. The reason for this is that the local topography is not as low lying as had been believed.