Date of Award

2008

Document Type

Senior Project

Degree Name

Bachelor of Science (BS)

Department

Geology

Abstract

The excavation of Judicial Ditch #66 has altered the topography of its hydrologic basin in Polk County, Minnesota. Records of how the pre-ditch landscape appeared do not exist. The original aim of this study was to develop and evaluate a method of manual data manipulation and combination to digitally restore the topography of a human-altered landscape.

Trial and error with the combination of spatial data from separate sources provided inadequate results. The study was subsequently divided into four parts. First, drainage area and its potential wetness were estimated using the 10 meter U.S. Geological Survey Digital Elevation Model (DEM). The ln(a/tan β) potential wetness index is used, which is directly related to drainage area. Second, points representing ditches and berms were eliminated from National Resources Conservation Service (NRCS) spatial survey data. Third, we compared wetness indices of the restored and original landscapes. Finally, the wetness index for the restored landscape was compared to a soil map of the study area to determine if the areas of wetness correspond with hydric soils.

GIS software provides helpful tools, which can produce models that can simultaneously show multiple layers of information for an area. By estimating areas of wetness, this method allows the effects of restoration to be determined prior to any physical alteration of the landscape. The display of data and models on GIS maps will play a large part in helping to solve other restoration issues in the future.

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