The instrument is moved by first reading the elevation . and distance to a 

 point on the profile line, and then using this point as a new TBM for estab- 

 lishing the instrument at another position on the profile line. A stake or 

 piece of wood makes a good turning point, and even the bottom of the level rod 

 foot can be used if the rod is not moved during the turning process. After the 

 profile survey is completed, it is necessary to "close" the survey by using a 

 turning point to carry the distance and elevation back to the original TBM. If 

 time permits, turning point calculations should be made before leaving the pro- 

 file line. If an error is found the line should be resurveyed. Even if turning 

 points are not used, a final reading of the elevation of the TBM should be made 

 to check the HI and close the survey. 



4. Surf Zone. 



To properly compare successive surveys of a profile line, it is important 

 that each survey extends to a consistent elevation, usually the survey datum. 

 Although surveys should be planned for low tide, surf -zone surveying is usually 

 required (Fig. 4). Surf-zone surveying is difficult because (a) the level rod 

 is often fully extended making it susceptible to movement by waves and wind, 

 and (b) it usually requires reading the smaller numbers on the upper sections 

 of the rod. Depending on the wind and wave conditions, the following proce- 

 dures are given: 



(a) Low wind and wave conditions. The RP simply continues the 

 survey to the datum intercept. 



(b) Moderate wind or wave conditions. During these conditions, 

 the datum intercept is relatively easy to reach but wind or wave 

 action prevents accurate stadia readings. The IP first turns the 

 instrument onto the beach near the RP and calculates a new HI. 

 This movement alone may make the stadia easier to read; if not, a 

 tape can be used to measure distance into the water. The end of 

 the tape is secured on the RP ' s wrist and the tape reel is pinned 

 into the beach under the instrument. At each station, the IP first 

 reads the elevation, then pulls the tape taut to read the distance. 

 Note that all distances are still relative to the instrument posi- 

 tion. 



Surf-zone surveying should be avoided during high wave conditions. If the 

 datum intercept cannot be reached, it can be extrapolated if the final two 

 survey points are close together and are along the straight part of the fore- 

 shore (Fig. 3) . 



5. Field Notes . 



The range, elevation, and the datum of each profile monument and TBM should 

 be recorded in a fieldbook before entering the field. Figure 5 shows a sample 

 page from a profile line survey recorded in the field, with appropriate column 

 headings filled in. The "range" column is used for actual distance measure- 

 ments of each survey point relative to the profile monument. Each stadia 

 reading, along with measured distances, is entered under the "stadia" column. 

 Note that these readings are relative to the instrument location, not to the 

 profile monument or TBM. Survey points or stations (STA) are numbered in the 

 first column. All readings should be to the one-hundredth place when using a 

 level rod graduated in feet or to the nearest centimeter when using a metric 

 rod. 



