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Minneapolis-Saint Paul Post

Upcoming Post Activity

Wednesday, 25 March 2015

Mapping Rivers and Lakes for Highways: Applications of Hydrography in Transportation

Petra DeWall
Waterways Engineer, MnDOT


A river’s contours are a mystery until they’re mapped.  Even then, the river moves and changes with high flows and debris.  Lakes, though less changeable, are unknowable without depth mapping.  This presentation will provide an overview of river and lake hydrography projects done by the Minnesota Department of Transportation Bridge Hydraulics-Waterways group.

MnDOT’s Bridge Hydraulics/Waterways group has mapped rivers and lakes for 16 years with survey-grade depth-sounders and an Acoustic Doppler Current Profiler (ADCP).  Depths, flow rate, velocity and direction are measured, mapped in ArcGIS and CADD and applied to project requirements.  Challenged by floods and low water alike, our equipment has been adapted to a wide variety of waterways, and we’ll share that experience.  Recently, we acquired a 3D sonar scanner device and will discuss what we have done to date and some exciting prospects for the future.


Speaker Bio:  

Petra DeWall is the Waterways Engineer for MnDOT.  She attended The University of Minnesota where she received her Bachelors degree in Civil Engineering and a Masters degree in Infrastructure Systems Engineering.  Petra heads up the Waterway Unit in Hydraulics which issues hydraulic reports on all new bridge projects, manages the scour program and works with the local units of government assisting with technical guidance on hydraulic and scour issues.  When not in the office, Petra likes to go camping with her husband Craig and son Bobby.

Meeting Schedule and Logistics:

  • Social time and lunch (if you so desire) will be from 11:30 AM to 12:30 PM in the dining room of the Officers Club.
  • The Club’s cafeteria-style lunches are typically $10.00 or less; people who partake in the cafeteria-style lunch will pay the Officers Club directly.  If you come only for the presentations, there is no charge. 
  • Post Meeting and Presentation will be from 12:30 PM to about 1:15 PM in the Lower-Level Meeting Room of the Officers Club.
  • 1-PDH for this Presentation.



Please RSVP with your intent to either partake in the cafeteria-style lunch or to come for the presentation only; this will help the Officers Club staff to ensure that an adequate amount of food is prepared.  Either leave a voice mail message with Michelle Larson at 651-290-5632, or click the RSVP button in the left-hand column, or send an email message to


Meeting Location: 

Fort Snelling Officer's Club near Post Road.  See map at: