STEM SIGHTS: The Concordian who uses satellites to measure river topography
What if you could obtain detailed knowledge of a river’s physical characteristics without ever having to get wet?
That’s precisely what Sho Harada is trying to do with his combined interests in computational fluid dynamics, hydraulics and remote sensing.
Harada is pursuing a master’s in applied science from Concordia’s Department of Building, Civil and Environmental Engineering. He’s part of the hydrotechnical engineering group led by professor S. Samuel Li, which focuses on hydraulics and numerical modelling.
“Hydraulic engineering searches for practical solutions to real-life problems,” Harada explains.
Recently, his paper on the use of remote sensing techniques for mapping river channel topography and sediment grain size won the 2017 Best Student Paper Award from the Canadian Society for Civil Engineering.
Using GPS and satellite imagery, Harada is helping to introduce remote sensing technologies into the research methods of fluvial hydraulics, which traditionally deploy hands-on techniques such as field survey.
‘Remote sensing technology allows for an all-encompassing view of the problem at hand’
How does this specific image (above) relate to your research at Concordia?
Sho Harada: This is a plot of a cross-sectional velocity profile, which shows the distribution of velocity across a channel, or how fast water is flowing at different points on a river. It’s overlain atop a contour map, which shows the depth of the water at those points through colour coding.
The plot is created by first generating a digital elevation model of the terrain from the field data and satellite images and then numerically simulating the river flow.
The numerical simulation works by taking the depth and velocity data and attempting to simultaneously solve for three sets of equations: one that describes the conservation of mass, one that describes the motion of fluid and one that models fluid turbulence. My research is directly interested in the use of numerical modelling and remote sensing for hydraulic engineering purposes.
What is the hoped-for result of your project?
SH: Remote sensing technology has been well-incorporated into the fluvial geomorphologist toolset for a while now. This is not the case among hydraulic engineers, however. I hope that my research can demonstrate the potential of such technologies as a supplementary tool to aid in engineering design and decision-making.
A major difference between hydraulic engineers and fluvial geomorphologists is that engineers use physical theories to design structures and management plans, while geomorphologists use those theories to interpret what they are seeing.
Hydraulic engineering falls under the applied science field, which searches for practical solutions to real-life problems. One main advantage of remote sensing technology is its large spatial extent, which allows for an all-encompassing view of the problem at hand.
What are some of the key areas where your work could be applied?
SH: The remote sensing project was actually inspired by the need for a fast and repeatable way to estimate sediment size in rivers for salmonoid habitat assessment.
Traditional field survey involves the use of trained personnel to snorkel/sift through sediments to determine the sediment size. It’s time-consuming and that often reduces the frequency of resurvey.
In contemplating this problem we came up with the idea of using satellite images to generate a digital terrain model, numerically model the river flow and estimate sediment size. This method is quick and, best of all, the frequency of resurvey is limited only by how often the satellite revisits the site, which is every two days.
The implications of a channel bed-to-mountaintop digital terrain model are far-reaching. Besides identifying salmonoid habitats, terrain models may be used for modelling water flow, flood plain delineation and mitigation planning, creation of relief maps, extracting terrain parameters for geomorphology and 3D rendering for visualization, to name a few.
What are some of the major challenges you face in your research?
SH: One of the biggest obstacles was combining data from two images that were captured in different days with different amounts of water flowing in the river. We used conservation laws to account for this discrepancy.
What advice would you give STEM students wishing to get involved in this line of research?
SH: The base knowledge for this sort of project is in remote sensing and computational fluid mechanics. Those who are interested would benefit from a sound mathematical and physical science background to understand the underlying theories and data processing/management capabilities to manipulate large data sets.
What do you like best about being at Concordia?
SH: My favourite part about Concordia is that it’s close to many other universities. This presented me with opportunities to regularly meet and discuss my research at local symposiums, which ultimately led to a collaborative research project.
I think it’s exciting and rewarding for researchers who are passionate about a common topic to be able to meet and connect with one another.
Are there any partners, agencies or other funding/support attached to your research?
SH: This project was carried out collaboratively with my supervisor S. Samuel Li, Michel Lapointe, a geomorphology professor at McGill University, and his PhD student Fabien Hugue. Financially, the NSERC Discovery Grant held by Li supported our work.
Find out more about hydraulic engineering research happening at Concordia.
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