AN EXPOSURE INDEX FOR OILED SHORELINES

Wave action is the most effective natural cleaning agent of oiled shor elines. Therefore, the degree of exposure of a shoreline to wave actio n dictates how quickly that shoreline will be cleaned by natural proce sses. In the absence of recorded wave data, a simplified exposure inde x, tested on the shorelines of Prince William Sound, Alaska oiled duri ng the Exxon Valdez oil spill, can be used to predict potential cleans ing by wave action. Wind gauge data correlated with three effective fe tch distances measured perpendicular to and at 45 degrees to the shore line are used to calculate the exposure index. In Prince William Sound , both biological and geomorphological criteria for exposure to waves agreed with the readings calculated for the index. Surface oil on the exposed shorelines was removed quickly during the first storm season. Sheltered coasts were cleaned more slowly. This technique should also work well for other partially enclosed water bodies. (C) 1997 Publishe d by Elsevier Science Ltd.