Working a job that entails creating an easement (Over tidal waters) for a dock/marina.?ÿ I need to indicate the location of the Mean High Water line.?ÿ Interestingly enough the NOAA datums for my area are a few hundred feet away.?ÿ ?ÿSo if I were to use the NOAA data located here --> https://tidesandcurrents.noaa.gov/datums.html?datum=MSL&units=0&epoch=0&id=8656394&name=NEW+RIVER%2C+JACKSONVILLE&state=NC
?ÿ That being said, could I shoot points along the rivers edge that's +0.26 ft above MSL to give me MHW??ÿ?ÿ
It depends on how much erosion/accretion is happening over time. If it is insignificant then you method would work.
How will you know what and where is the MSL line? The water's edge is moving up/down because of the waves as you shoot it at a certain time based on the tide tables. 0.26ft seems like a small value to determine from a moving water line. And how are you going to certify that elevation?
VDATUM
Include the date and time you made the determination in the field. It's a time stamp of an ambulatory boundary.
@jt50 The water's edge is irrelevant. He's looking to measure the location of the MHW contour. Measure a strip of topo from above extreme high water down to roughly at low water, then interpolate and draw a contour at MHW elevation.
I do a significant amount of work that needs tidal datum information. We do dock permitting and of course boundary surveys where the ownership lines are to MHW (in NH) or MLW (in Maine). My methodology which seems to work well is to find the nearest NOAA station that represents the conditions at the property I am working on (constrictions, ocean facing, up river, etc.) and use that station to determine the elevations of the relevant water elevations. I state on the plan which station is the basis for MHW, MLW, MLLW, etc. and the elevations they are shown at. In my mind, this is superior to locating observed high tide and low tide over a lunar cycle because it is reproducible and not dependent on estimations and errors in user observations.?ÿ