Hydrographic Surveys

Note:  The information shown on these surveys is solely for informational purposes and not to be relied on for engineering or navigational purposes.  Depth data shown is only accurate for the date and time of the survey.


Surveys show elevations above mean sea level of the river bottom contours.  Water surface elevation for the time of the survey is shown in the lower right corner of the survey.  To determine the water depth, subtract the elevation of the river bottom contour from the water surface elevation.

Hydrographic surveys are collected with either a "single-beam' or "multi-beam" transducer.  Single beam surveys are typically cross-sectional surveys where survey lines are run at predetermined intervals.  Data between the survey lines is interpreted based upon actual data from adjacent survey lines.  Multi-beam surveys are swath or sweep-type surveys where one transducer produces a fan-shaped echo-pulse that typically covers an area between 120- and 90-degrees.  This produces near complete coverage of the river bottom.