A GIS Implementation of a Sediment Transfer Model to Local Coral Reefs in the Bay Islands, Honduras

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Committee Chair

Tarek Rashed, Ph.D.

Committee Members

Glenn Hyman, Ph.D.


The World Resources Institute (WRI) developed a “Reefs at Risk” model which is used as a map-based indicator of the threat to coral reefs. Data from the “Digital Atlas of Central America” (1999) created by the United Stated Geological Survey (USGS) and the “Atlas of Honduras” (1999) created by International Center for Tropical Agriculture (CIAT) was used in the testing of this model which was translated into GIS methodology. WRI has identified sediment from inland activities as a threat to coral reefs. The basic objective of this research was to facilitate the study of variables affecting the volume of sediment entering watersheds, and quantify the threat to coral reefs using Geographic Information Systems (GIS) and spatial analysis. The coral reefs that this study was focused upon are the reefs of the Bay Islands off the coast of Honduras in the Caribbean Sea.

The WRI’s model suggests that the volume of sediment entering watersheds is affected by five variables: (1) terrain slope, (2) soil, (3) land cover, (4) precipitation, and (5) the watershed basin size, which represents the distance sediment travels before reaching the basin mouth. These environmental variables were compared to one another in terms of their physical locations and the watershed basin to which they belong based on quantitative values for the slope, soil, land cover, and precipitation. These values were used in the “Reefs at Risk” model equations, which calculate the threat posed by inland sediment.

The results of this project show that the proposed methodology can assist in assessing the threat of sediment to coral reef. The results of this study are maps of relative erosion potential and relative sediment delivery to the mouths of the watershed basins, and sediment dispersion to the local coral reefs. This study shows how GIS tools and procedures can be used to model, simulate, and quantify natural environmental characteristics and their mutual affects upon one another.

Full text is available at the University of Redlands


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