Date of Award

5-2014

Document Type

Thesis

Degree Name

Master of Science (MS)

College/School

College of Science and Mathematics

Department/Program

Earth and Environmental Studies

Thesis Sponsor/Dissertation Chair/Project Chair

Joshua C. Galster

Committee Member

Duke U. Ophori

Committee Member

Clement A. Alo

Abstract

River baseflow is the river discharge supported predominantly by groundwater, and can be greatly impacted by changes in land. Intuitively, the baseflow of a river would decrease with increased urbanization, as urbanization increases the amount of impervious surfaces, limiting the ability of precipitation to infiltrate into the ground and recharge the local groundwater. However, evidence suggests that the baseflow of rivers in urbanized areas can increase as a result of leaky subsurface water infrastructures that add water to groundwater and replenish baseflow. Another reason for the baseflow increase in urbanized watersheds is that water supply systems are over-pressurized by design to reduce the chances of contamination, contributing extra water to the local system. Cities that have decreased in population over the last century may experience an even greater addition to baseflow as leaky water infrastructures may not be attentively maintained due to the fact that there are less people in the area to supply water to. Given these conflicting urban influences on baseflow, it is important to investigate this relationship further. The goal of this project is to empirically investigate how decreased population in urban areas has impacted baseflow in the Midwestern region of the United States, informally called “The Rust Belt”. The project uses USGS gage data from streams within the Rust Belt, specifically from the states of Michigan, New York, Pennsylvania, and Ohio. Stream gage data was selected under the criteria that the data was continuous (> or = 40 years), unregulated, and a drainage basin of < or = 400 square miles. Six metrics of annual discharge used are 1) baseflow per unit drainage area (BF, m3/yr); 2) runoff (RO, m3/yr); 3) total flow (TF, m3/yr); 4, 5, & 6) and a ratio of these flows to precipitation over area (BF/P/A; RO/P/A; TF/P/A, unitless). The results determined that there is mainly a positive relationship between depopulation and baseflow in depopulated cities that lie within the geophysical province of the Central Lowlands.

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