Student: Zhihao Cheng, Madeline David, Casey Urban
Project: River Meanders: Experimental And Observational Results of a Fundamental Instability | View Poster (PDF)
Institution: Lehigh University
Major: Environmental Engineering, Earth & Environmental Science, IDEAS
Advisor: Panos Diplas, Dork Sahagian
Abstract
Rivers with erodible banks represent one of several meandering systems. Other such systems include the Gulf Stream, non-aerated water falling from a faucet, derailed trains, and jackknifed tractor-trailers. We advocate that the fundamental cause of the instability that leads to meandering exists when a fluid is decelerated due to an obstruction or perturbation. This type of perturbation occurs when a river flows into an ocean or into a section having sufficiently milder slope, a truck cab brakes, or a blockage disrupts a flow of faucet water. We also suggest that meandering can manifest in one, two, or three dimensions, depending on geometrical constraints orthogonal to the flow direction. The initial laboratory results identify an instability under conditions of decelerating flow, but not under conditions of accelerating flow. These results are complemented by remote sensing observations from Google Earth Engine, which demonstrate meandering behavior in cases of slope reduction and subsequent deceleration. Other examples demonstrate straightening behavior in cases of accelerating flow, such as upstream of a waterfall. A universal theory for meandering systems in one, two, or three dimensions can be developed from these experiments and observations. This augmented knowledge of meandering systems will allow for a better understanding of future river channel evolution, especially in the face of rising sea levels as a result of climate change, bridge scour evaluation, river engineering or channelization, and heat transport by the Gulf Stream.
About Zhihao Cheng
About Madeline David
Madeline David, is a senior at Lehigh University majoring in Earth and Environmental Sciences and Environmental Studies, and minoring in English. She conducts research on river channel morphology with the Civil & Environmental Engineering Department at Lehigh. She joined the research team through the Mountaintop Program during the summer of 2018, and has continued working on the project into the 2018-2019 academic year. In addition to her research, Madeline is the captain of the Lehigh Women’s Club Soccer Team and is a teaching assistant for an introductory level environmental science course. She also has had professional internship experiences with environmental conservation, education, and entrepreneurship, and earned her LEED Green Associate credential in August 2018. After graduation, she plans to pursue a career in sustainability research, sustainability consulting, or environmental advocacy.
About Casey Urban
Casey Urban, is a senior in the IDEAS program concentrating in Environmental Engineering and Earth & Environmental Science and History. She joined the meandering research team with the Civil & Environmental Engineering Department in the summer of 2018 as part of Lehigh’s Mountaintop program. This research has been continued in the 2018-2019 academic year. She is involved on campus as a Gryphon (Resident Assistant). This role involves mentoring first and second year students, programming events, and leading fellow Gryphons. She served as president of Alpha Omega Epsilon, a professional and social engineering and technical science sorority, her junior year at Lehigh. She also serves as the president of Lehigh’s American Academy of Environmental Engineers and Scientists (AAEES) chapter. Casey will continue the meandering research through a Master of Science degree in Civil Engineering at Lehigh University beginning in the summer of 2019.
