Kind of getting off the topic a little, but generally speaking I would wonder if you were readying to the nearest foot, or the nearest hundredth of a foot (Or whatever). That is what I would mean if I was asking what your precision is.
Anyway, if anything was possible, I would use something like this, and check with occasional physical measurements.
We had a few wet well gaging stations that were deployed prior to my position as the Utility GIS Coordinator of a water hungry city along the front range of Colorado. During construction/repair, They were measuring the water with a cm accurate Single Base solution and were "getting close" enough with a flat rock in the shoreline until it was windy.?ÿ I helped the GIS Tech 'build' a 'stilling' buck to attenuate the waves caused by the wind and waterfowl etc,to use the topo shoe for the .01 plate as a guide,?ÿ and was imbued by the water resource engineer to beware the seiche, and always take several measurements before collecting and heading back to the office.
We'll be using the level and rod for an elevation at the pond. One hundredth may be achievable. The data is for an elevation certificate and latter of map amendment.
We will try to use the pond elevation as a bench mark on the same day to get the elevation of the dam and free board. We will also be using the survey instrument (1 second resolution) for a three dimensional coordinate at the dam and compare the results.
It's not a long term project so I doubt if I can afford the data logger.?ÿ?ÿ
Historic boundaries and conservation efforts.
I'm applying to FEMA for a letter of map amendment on two properties at the pond.
Historic boundaries and conservation efforts.
You mention a dam, this implies the pond is a reservoir, unless it's a pit/dike structure. Anyway what FEMA needs is a flood elevation which in a normal dam/reservoir will be the spillway elevation plus the elevation of a 100 year flood event overtopping the spillway. The critical information is the spillway elevation, spillway capacity and the calculations that determine a 100 year flood volume.
You need the critical information of drainage pipe and trickle tube, what they are made of and how they work, the trickle tube elevation and capacity, the drainage pipe, nice to get it's elevation but often that isn't possible easily.
Topo the spillway or cross-section profile it.
Hand all this information to an engineer and they will do the calculations to determine the 100 year flood elevation of the reservoir. The water level in the pond has little to do with a flood elevation or HWL of the pond. I wouldn't have even bothered with it. My guys have learned to ignore the water in any reservoir/dam job.
I'm assuming that there is no FEMA map for this area.
They will or should want an engineer's report. I can't imagine anyone built a house lower than the spill elevation behind this dam, that would be a problem.
If I can walk up to the edge of the pond I just shoot where the water intercepts the land, but any of the means stated above would work.
@mightymoe I am learning the history of the area surrounding the pond and it seems to have been constructed to serve as a recreational area. I have yet to visit the dam as it is on private property and so I have scheduled an appointment.
I do know that there have been 8 or more letters of map amendment approvals in the near vicinity. So, I will ask if any engineering studies were done for those approvals, but, I doubt it. There is a FEMA map of the area, but no base flood elevation.
Thank you and everyone else for your thoughts and advice.
Historic boundaries and conservation efforts.
If I can walk up to the edge of the pond I just shoot where the water intercepts the land, but any of the means stated above would work.
All day long.
All day long.
Water's edge changes ALL DAY LONG too unless it's frozen
All day long.
Water's edge changes ALL DAY LONG too unless it's frozen
Then stay there all day and take a shot every half hour and average for the day. Why not make it every 15 minutes. How about every 5 minutes?
Only thing going to change any of my ponds right now is evaporation and consumption by livestock.?ÿ Getting the cattle to leave the pond would be required to avoid a false reading by 0.001 feet
which is why there is a thing called a tide gauge that you set to read at pre-set intervals and leave it under water and come back after weeks or months and download the water level.
Since this is for a FEMA submittal and there are already submittals for this pond then I would first look at those existing submittals and find out what BFE they are using. Then be sure it makes sense to conditions at the dam. The water level at any time is irrelevant unless you are at the dam during the 100 year flood event. Much like the overtopping of the Oroville Dam spillway all dams have a number. That number is not related to water during non flood times.?ÿ
?ÿ