VICKSBURG, MISS.-- What did it take for the four-member research team who developed the “ISSDOTv2 bedload transport methodology” to create a U.S. patent-worthy invention? For this team, it was made possible by varied expertise, a combined 86 years of experience, a desire to solve river sediment challenges and helpful friendships.
A resident of Magee, Mississippi, Tate McAlpin joined the U.S. Army Research and Development Center (ERDC) in 2002 as a co-op student and transitioned to full-time in 2005 in the Coastal and Hydraulics Laboratory (CHL) River and Estuarine Engineering Branch.
His areas of expertise include 2D and 3D numerical modeling of rivers and estuaries, as well as numerous projects measuring bed-load transport rates and analyzing associated hydraulic and sedimentation impacts.
“My role on the ISSDOTv2 team has primarily been in the transition from the basic equation of bed-load to a numerical method capable of providing consistent and accurate results in a timely fashion,” McAlpin said.
David Abraham is a member of the CHL River and Estuarine Engineering Branch and a resident of Vicksburg, Mississippi. His expertise in numerical and physical modeling of riverine hydraulics, sediment processes, structures and geomorphology guided the team during the invention process.
During his 33-year career at ERDC (formerly known as the Waterways Experiment Station), Abraham was the primary developer of the original ISSDOTv2 equation of bed-load transport.
“’What? You mean we can send a man to the moon, but we can’t measure the amount of sand moving on the bottom of large sand-bed rivers?’” Abraham asked himself as an initial reaction when discussing the topic with U.S. Army Corps of Engineers personnel in the late 1990s.
Then when viewing the new (at that time) multibeam bathymetric data of river bottoms with Thad Pratt, the seed was planted as to how it could be done. A four-month CHL research grant carried out at the Iowa Institute of Hydraulic Research (IIHR) in 2008 provided the time and environment to finalize a mathematical functional relationship.
The rest is history, as they say,” Abraham said. “And that history came about through the creative brilliance, dedication and hard work of every team member.”
Working as a hydraulic engineer for 11 years, John Shelley joined the invention team from the U.S. Army Corps of Engineers Kansas City District in Independence, Missouri, where he works with the River Engineering and Restoration Section. He contributed expertise in data collection processes and methodology.
“My role was relatively small in the overall development of ISSDOTv2,” Shelley said. “I was doing a developmental assignment at CHL in February 2011 when I met David Abraham and Tate McAlpin.”
Shelley explained that Abraham had recently computed ISSDOTv2 bedload data from multibeam surveys on the Missouri River in his home district.
“(Abraham) said, ‘I’ll give you the data and you can play around with it,’” Shelley recalled. “When I plotted the values for bedload transport, I noticed an interesting pattern—the longer the time between surveys, the lower the computed value for bedload transport.”
Abraham suspected that the drop in the computed transport values was due to regions of the river that scour and then refill between when the surveys are measured.
“I devised a method to eliminate the bias by fitting a line to the observed transport values and extrapolating. We published this finding in the Journal of Hydraulic Engineering, and this correction became standard practice in the ISSDOTv2 procedure,” Shelley said, adding that he is an advocate for additional ISSDOTv2 collection in support of his Missouri River Bank Stabilization and Navigation Project and Missouri River Recovery Program.
As CHL’s Military Technical Director, Vicksburg native Thad Pratt added his expertise to the team as a research physicist, along with his 32 years of ERDC experience. He has provided oversight and leadership for numerous projects, including those of other invention teams.
Pratt’s projects focus on river sediments and understanding their distribution, particle sizes, historical data and related information. This leads to planning and working with existing natural processes to minimize navigation and flood risk challenges while enhancing natural habitats.
“Sediments are important to the health and welfare of the river,” Pratt said. “Certain types of fish and invertebrates need certain sediments. If this sediment isn't being delivered, that fish or that invertebrate will not be living in that river reach.”
Sediment load drives many of the natural processes that impact the river, so the invention to measure the amount of sand moving on river bottoms is important.