Master of Science (MS), Ohio University, 2012, Civil Engineering (Engineering and Technology)

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.

Committee: Tiao Chang (Advisor) Subjects: Engineering; Geography; Geology

Master of Science (MS), Bowling Green State University, 2007, Geology

The Village of Pemberville, Ohio experiences frequent flooding. Accurate flood maps are needed to reduce damage caused by these floods. Photogrammetry software was used to create a high-resolution DEM using two overlapping USGS NAPP aerial photographs each with resolutions of 1:40,000 and scanned at 1800 DPI. The resulting DEM had a resolution of 0.57 m (1.87 ft) and a minimum detectible elevation of 0.95 m (3.1 ft). HEC-GeoRAS was used to produce cross-sections of the North Branch of the Portage River and an inundation map of a 100-year flood from the high-resolution DEM. The inundation map was compared to a 100-year flood inundation map produced with ground surveyed cross-sections provided by TMACOG and the FIRM for Pemberville. The datasets produced flood profile elevations of 196 m (643 ft) along the North Branch of the Portage River in the Village of Pemberville, which is the same as on the FIRM. When compared areally, the high-resolution DEM data produced larger flood extents than both the surveyed data and the FIRM of the village due to the length and distance of the cross-sections. Different lengths and large distances between cross-sections can cause large changes in the width of the bounding polygon, not accurately representing the floodplain, and limiting the extent of the estimated inundation.

Committee: Enrique Gomezdelcampo (Advisor) Subjects: