The primary objective of this research was to study sedimentation and erosion in the Tappan Lake Watershed. A bathymetric survey performed in 1998 by the United States Army Corps of Engineers had identified the lake as having a sedimentation rate five times greater than other lakes located in the region. Erosion and sedimentation were studied by using data from a 2011 bathymetric survey, the Revised Universal Soil Loss Equation (RUSLE), and a Geographical Information System. The conclusion of the study was that Tappan Lake does not have a sedimentation or erosion problem.
Secondary objectives of the study were to evaluate the effects of Digital Elevation Model (DEM) resolution on the terrain related variables of RUSLE, L and S factors. Comparisons of RUSLE results were made using 3-, 9-, and 27- meter DEMS which showed that estimated erosion potential decreases as DEM resolution increases. The results also demonstrated that DEMs with resolutions greater than nine meters are not appropriate for calculating terrain characteristics, as they are incapable of clearly defining areas where overland flow accumulates or where deposition should occur.