Topographic Survey

 

The topographic survey consists of using surveying equipment to collect a series of points and lines that capture topographic features within the stream channel and surrounding floodplain.  Each point is attributed with a location (X, Y, and Z coordinates) and a descriptive code.  Points with the same codes can also be connected to make lines.  These points and lines are used to construct a Digital Elevation Model (DEM) that represents a continuous gridded surface of the channel topography.  During the topographic survey, the responsibility of the person operating the prism rod is to efficiently survey points and lines that accurately represent the channel’s topography.  The person operating the survey instrument (Total Station) instructs the instrument via a software interface to measure the location of the rod and conduct trigonometric calculations to obtain a coordinate for the location of the ground at the bottom of the rod.

The images below depict survey data in various stages of GIS processing.

 

This is a digital eleven model, with water depth, thalweg, centerline and channel unit markers derived by a Champ crew from topographic survey data.