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Amanda Ritter and Emma Williamson

Quantifying Human Impacts on Hydrologic Signatures

Department: Civil and Environmental Engineering
Advisor: Tara Troy

Abstract:
Although there are many known factors that impact how a river basin will respond to hydrologic conditions, unanswered questions remain about the effects of urbanization, particularly across a range of spatial scales. Hydrologic signatures are indices that provide a useful way to assess the variation in catchment responses to streamflow and precipitation. Using MATLAB, we calculated six hydrologic signatures for 3005 USGS streamflow gages. These six signatures were runoff ratio, streamflow elasticity, slope of the flow duration curve, snow day ratio, rising limb density, and base flow index. Various regions in the US were analyzed from over the time period of 1950 to 2014. In order to determine the relationship between these indices and urbanization, stepwise regression was used to evaluate the impact of urbanization indicators -- housing density, population density, and impervious surface area -- and the hydrologic signatures. We find urbanization does not impact hydrologic signatures in the expected manner presented in hydrology textbooks, showing that stormwater management has had a significant impact on urban basin response, even in regions developed before the Clean Water Act. A deeper understanding of the relationship between urbanization and river response will benefit urban planners, civil engineers, and hydrologists in future water resources engineering research.

About Amanda Ritter:
Amanda Ritter is a junior at Lehigh University pursuing a B.S. in Environmental Engineering. She has a strong interest in the water resources demands of a growing population and is passionate about understanding human impacts on the environment. Amanda is also the President of Lehigh’s chapter of the American Society for Engineers and Scientists. She is a former Lehigh Tour Guide as well as a Volunteer Tutor for America Reads America Counts. In her free time, she enjoys reading, hiking, and community service.

About Emma Williamson:
Emma Williamson is a junior at Lehigh University pursuing a B.S. in Civil Engineering. She is focusing in Water Resources Engineering and plans to pursue a Master’s degree at Lehigh. Outside of academics, she plays the violin in Lehigh University’s Philharmonic Orchestra and is the vice president of Lehigh’s American Society of Civil Engineers club.