Luo, Wei (Professor)
M.S. (Master of Science)
Department of Geography
Land use--Wisconsin--Lake Ripley; Water quality--Wisconsin--Lake Ripley; Watersheds--Wisconsin--Lake Ripley
Eutrophication of lakes occurs naturally over time but with the influence of humans, mainly through the process of non-point source pollution, the eutrophication rate can be accelerated. Agriculture and residential land use along with the presence of impervious surfaces can negatively impact water quality of lakes due to nutrient pollution. This research investigates the impacts of land use on the water quality of Lake Ripley in Oakland, Wisconsin from 1993 to 2011 using a regression, correlation, and trophic state index (TSI) trend analysis. The regression analysis incorporates four years of National Land Cover Database (NLCD) data, eight spatial categories created through the hydrology technique, flow length, in ArcGIS Desktop from a lidar derived digital elevation model (DEM), and a weighting technique to calculate land use percentages. Agricultural land use, precipitation, and water quality data from Lake Ripley were compiled by date and a regression was performed on the dataset. The results indicate that the combination of agricultural land use and precipitation increase chlorophyll a and phosphorus concentrations, while these variables decrease the water clarity of Lake Ripley. The TSI classification of Lake Ripley fluctuates between mesotrophic and eutrophic conditions and has most often been described as mesotrophic in recent years which is likely due to the decrease in agricultural land use near Lake Ripley and its inlet stream. Agricultural land use within the two spatial regions closest to Lake Ripley and its inlet stream have the largest impact on Lake Ripley's water quality, whereas the land use within the other six spatial regions had relatively no effect on the lake's water quality. This result is inconsistent with the literature as only land use activities near these water bodies impact the water quality and not the entire watershed as stated in other studies. However, this may be explained by the nearly flat topography of the Lake Ripley watershed, resulting in reduced amounts of runoff. Topography and distance determine the areas of land that have an impact on the water quality within a watershed and should be considered in a water quality and land use impact analysis.
Whalley, Kyle, "The pressure of society on water quality : a land use impact study of Lake Ripley in Oakland, Wisconsin" (2016). Graduate Research Theses & Dissertations. 6108.
iv, 89 pages
Northern Illinois University
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