The Environmental Sensitivity Index (ESI) is a standardized method for mapping and inventory of sensitive resources.  ESI is a widely used system for ranking and classifying shoreline sensitivity based on characteristics such as degree of wave energy, potential penetration of oil into the substrate, and natural oil retention times of the shore type.  Other characteristics also contribute to shoreline sensitivity, including human use, wildlife use, industry activities, and socioeconomic importance (International Maritime Organization and International Petroleum Industry Environmental Conservation Association [IMO/IPIECA], 1996). 

Originally developed by Petersen et al. (2002), ESI Shore Type classification is a useful planning tool for identifying sensitive areas and resources at risk in the event of an oil spill.

ESI mapping provides a concise summary of resources that may be at risk, such as an oil or chemical spill or a natural disaster event in a GIS friendly format.  ESI maps are valuable tools and help to identify vulnerable areas, establish protection plans, and develop cleanup plans.  

References:

- International Maritime Organization and International Petroleum Industry Environmental Conservation Association (IMO/IPIECA).  1996.  Sensitivity mapping for oil spill response.  Report Series Vol. 1, London, U.K.  24 pp.

- Petersen, J., J. Michel, S. Zengel, M. White, C. Lord, and C. Plank.  2002.  Environmental Sensitivity Index Guidelines, Version 3.0.  NOAA Tech. Memo.  Seattle, WA.  89 pp.+ app.