Portland State University. Department of Geography
Term of Graduation
Date of Publication
Master of Science (M.S.) in Geography
Disappeared Streams, Flood Risk, GIS, Hydrology, Land Use Change
1 online resource (vi, 51 pages)
Many urban streams have been moved, culverted, buried, or "disappeared" as urban infrastructure was constructed. This loss of natural streams provided land for urban development, but as climate change increases the frequency and severity of extreme weather events, these disappeared stream areas could threaten homes and other infrastructure with increased flood risk. This study developed spatial data layers to identify many of these lost streams for Atlanta, Georgia, Baltimore, Maryland, and Phoenix Arizona, using historical maps to find streams previously visible that disappeared by the present day. This process used the oldest available georeferenced maps from the United States Geological Survey and georeferenced scanned maps to better identify disappeared streams in downtown areas. A previously developed dataset of disappeared streams for Portland, Oregon, was also used as part of this study. To understand if these disappeared stream areas have a higher flood risk, data from the First Street Foundation that predicts flood risk at the parcel level was compared to disappeared stream locations. The comparison found higher flood risk in the 100m buffer compared to areas farther away than 100m for all of the study areas. Current land cover (2019) was evaluated around these disappeared streams, which found high levels of impervious area around these areas. It is also important to understand if disappeared stream locations are related to the value of housing, thus a hedonic analysis of house sale price in Portland, OR that included spatial variables representing disappeared stream locations was conducted. This analysis found that including a disappeared stream variable reduces the effect of proximity to existing streams on house sale price. This is the first study to explore if the proximity to disappeared streams affects house sale price.
©2023 Gregory Christopher Post
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Post, Gregory Chrisopher, "Disappeared Streams and Flood Risk in Atlanta, Georgia, Baltimore, Maryland, Phoenix, Arizona, and Portland, Oregon" (2023). Dissertations and Theses. Paper 6534.
Available for download on Saturday, September 28, 2024