Figure 2-4. Survey rod in operation on Line 6 



survey position relative to the origin from the distance and angle measured by 

 the Geodimeter. The correctness of these coordinate values was checked by 

 comparing Geodimeter measurements to known locations on the tank and by 

 comparing cross-tank (y) values along each profile line, because the y-value 

 should not have changed for a given profile survey line as the carriage moved 

 along the channel. 



Beginning at the origin and moving offshore, the portion of interest of the 

 channel (normally, the entire channel length up to the location of the other 

 two carriages that were moved offshore to allow the profile survey carriage 

 access to the channel) was surveyed in the three sections shown in Figure 2-3. 

 During a few tests, lack of clearance under the survey carriage rod necessi- 

 tated that Section I of the profile be surveyed by a hand-held rod with a top- 

 mounted prism. Tracking of the prism was sometimes difficult in this section 

 due to window glare and the proximity of the prism to the Geodimeter. The 

 error introduced is discussed below, but it is noted that the water did not 



Chapter 2 Beach Profile Surveys and Sediment Sampling 



45 



