THE SEDIMENT SUSCEPTIBILITY INDEX: A TOOL FOR GUIDING ISLAND DEVELOPMENT
The primary objective of this project was to develop a tool, termed the Sediment Susceptibility Index (SSI) that can be easily used to help guide island development and “decision making”. The SSI is a means of comparing the susceptibility of coastal environments to changes in sediment accumulation due to land use changes in the up-gradient watershed. The SSI is defined as the “degree” or “magnitude” of the deviation in sedimentation, called “human impacted”, from “naturally" deposited sediments. The SSI consists of a five tier ranking system (least susceptible/no deviation to most susceptible/maximum deviation) of coastal sediment input/accumulation susceptibility. The tool developed here dominantly measures the rate of input of island-derived sediments to a coastal environment vs the capacity of the marine physical processes (waves, tides, currents) to export that material out of the adjacent coastal environment(s).
The integration of sediment distribution and accumulation rates with other data will help to determine the extent of sedimentation changes due to anthropogenic activities throughout the territory as well as other similar island settings. The SSI can also aid in identifying watersheds with the greatest potential for sedimentation impacts and aid in identifying patterns and trends to target emerging problematic watersheds.