GPS Coordinates

Only thing I am aware of are land surveying tools and equipment.

Example

The more you pay the less manual calculation and estimation you need to do. On the plus side you should be able to hire the equipment.

That doesn't meet my specifications. All of those require getting to the point by a person. I have some of those already. With all these pixel measuring devices, it seems like what I need is out there somewhere.

You can get your approx altitude with the gps in your phone and google earth...so punch in your gps coordinates to google earth, and measure distance and direction from your position to position you want to measure...

Alternatively you could use a drone with an altimeter...

The accuracy will be lacking without proper equipment and measuring technique...

I think what you need is an inclinometer

...and maybe something like this...

...or maybe if you have deep pockets...

https://wingtra.com/drone-photogrammetry-vs-lidar/

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2002WR001317

The abstract cited is of an excellent reference technique to estimate surface water velocity from a nearby bridge with reference to a stationary control point.

It sounds like the OP wants to be in one spot, and then, measure the differences in horizontal, and vertical, distances in order to determine the location and elevation of another point which is well-removed from the OP's location.

Of course, GPS devices can provide the local lat. and long. of the observer's location, and electronic distance measuring devices (i.e.: EDMs) can be used to measure the slope distance, and it's horizontal and veritical angles to a relatively nearby remote point.

But, the ''catch'' is that a second person has to wrangle the (surveying reflector/prism on a float) over to that second point in order for the electronic signals to be reflected back to the the viewer's location.

It is possible that more advanced electronic survey equipment does now exist to do all that, but to what accuracy remains to be learned. Sooooooo, ask a (surveying equipment supplier) if any such equipment now exists, etc. In any case, good luck.

Measuring the changes in riverbed bottoms, and subsurface flow-profiles, over time, are each another matter...

Land in the water, drop line with sinker to measure depth, raise anchor, let drone float along at water velocity, measure time over distance...calculate average speed from middle to side with depth...

Catch fish for dinner....

That would be great except that I want to measure the section before the water gets there. I want to know the height of the water for different flow rates.

So you are measuring a dry river bed?

Yes. But not accessible due to terrain or trespass laws.

I would use a drone with measurement instrumentation attached...you could measure the depth and the width at various locations, then you would need a curve for the possible flow rates, or normal flow rates...

One way to measure flow is to solve the following equation:

https://archive.epa.gov/water/archive/web/html/vms51.html

USGS Stage-Discharge Relation Example.

The continuous record of stage is converted to streamflow by applying a mathematical rating curve. A rating curve (fig. 3) is a graphic representation of the relation between stage and streamflow for a given river or stream. USGS computers use these site-specific rating curves to convert the water-level data into information about the flow of the river.

The development of an accurate stage-discharge relation requires numerous discharge measurements at all ranges of stage and streamflow. In addition, these relations must be continually checked against on-going discharge measurements because stream channels are constantly changing. Changes in stream channels are often caused by erosion or deposition of streambed materials, seasonal vegetation growth, debris, or ice. New discharge measurements plotted on an existing stage-discharge relation graph would show this, and the rating could be adjusted to allow the correct discharge to be estimated for the measured stage.

Converting stage information to streamflow information

Most USGS streamgages transmit stage data by satellite to USGS computers where the stage data are used to estimate streamflow using the developed stage-discharge relation (rating). The stage information is routinely reviewed and checked to ensure that the calculated discharge is accurate. In addition, the USGS has quality-control processes in place to ensure the streamflow information being reported across the country has comparable quality and is obtained and analyzed using consistent methods.

Most of the stage and streamflow information produced by the USGS is available online in near real time through the National Water Information System (NWIS) Web. In addition to real-time streamgage data, the NWIS Web site also provides access to daily discharges and annual maximum discharges for the period of record for all active and discontinued streamgages operated by the USGS.

Maybe this information is already being monitored...?

I want it without any water. I've done these calculations in earlier years. But data was collected on the ground. Today, it's not that easy all the time. I calculate the flow from the old Q=CIA formula. Then, I calculate the elevation in the stream bed that will give me that flow. But to get the elevation of the water in the stream bed, I need a cross-section of the stream bed. I want to get this cross-section without getting on the ground. I think it's possible. I just need the right instrument to do it.

I think I would use 2 drones, one to suspend a reference measurement, like a 1 meter stick, and one to take photos from different angles, with that information an accurate calculation could be made...

https://www.propelleraero.com/blog/drones-changing-game-topographic-surveying/

Some states and/or local governments now have high quality LiDAR data available either for free or it can be purchased. The accuracy will depend on things like tree cover etc... I have found it to be accurate enough in most cases. You may need to have some GIS knowledge to create transects from the data depending on the type of data available. In most cases you will be able to get data at 2-foot contour intervals or better. For example, on the Texas Natural Resources Information System website they have a whole section dedicated to hydrography as well as elevation LiDAR data.

https://tnris.org/stratmap/elevation-lidar/

It looks like Texas is mostly 5-foot contours.

I would recommend using something more rigorous than the Rational Method. This may be a reasonable method for a first cut but I would not design anything based solely on the Rational Method unless you intend to use a very large safety factor.

I'm wanting to analysis small drainage areas. For instance, there's a vacant lot with a gully crossing it. The owner can't get a building permit without a hydraulic study to justify the increase in water level. I want to make the hydraulic study. To get permission to get on the property may be problematic sometimes. That's why I need a device to get the data without physically getting on the property. The "image meter" seems like what I need but I can't get it to download to my computer. It seems to only download to a phone and my phone isn't on the list. Anyway, I'll keep working on it to get it on my computer. Thanks for your comment.

I think you need to design so that you have no increase in water level, I don't know of many (any) place that will allow for anything more than a negligible increase in the hydraulic grade line. You need to design a detention pond to attenuate the increased peak and also for water quality standards. If this is in Texas the other resource you should be consulting is the Texas Department of Transportation, even if it is not going to affect a highway it is a good design resource.

http://onlinemanuals.txdot.gov/txdotmanuals/hyd/hydrology.htm

I am a retired engineer from the Texas Dept. of Transportation. I did these type calculations may years ago. We were allowed a foot of head at the culvert entrance. Then we would check upstream to see if it impacted private property. I haven't checked with the city yet, but I'm sure a 0.1 foot rise wouldn't prevent the property from being developed because then they could get more tax dollars. I estimate a 12 inch square piling wouldn't raise the water level no more than that. However, they would require calculations to justify that before they would issue a building permit.

Counter Top installers use devices like this, what you need to specify is your optimal range, distance from your instrument to the target.

These mapping machines are accurate to millimeters, perhaps at long range +/- 2.5” might work, these are $6k to $9k, from what I remember the installer saying.

The Trimble Geo 7 with rangefinder attachment may be what I need. I sent them an inquiry.

Thanks

I would say a UAV equipped with a proper 3D Lidar would do the trick. With the right wavelength it can measure below the surface of the water with the required accuracy. Of course the clearness of water is a factor.

There are a lot of companies offering Lidar mapping and measuring services with drones, you just have to find the right one.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4721784/

The what3words ap gets you within 3m of anywhere at no cost. Used by the emergency services in the UK.

Why not use a LIDAR scanner to find the elevation and position of the points you wish to know. I have watched several programs where LIDAr was used to scan pyramids and tomb passages.

Recently I saw a program where they used a LIDAR on a drone to do the same thing over inaccessible jungle to find tracks and roads.

Same equipment was used to scan the Mexican/Inca pyramids and buildings.

"calculate elevation of flow for different flow rates (25 year, 50 year, etc.)."

Can you explain that in more detail?

When you say "elevation of flow": do you mean the depth of the water?

Do you have the historical flow rates (25 year, 50 year etc.)?

I mean the top of the water at that location. A 25 year rainfall contributes so many CFS, a 50 rear rainfall contributes more etc. To get the CFS is a different calculation. I'm wanting the surface elevation of the runoff at that location. Then, I can calculate the rise in elevation for any encroachment added such as fill to increase the useable space next to the stream.

What no one is mentioning is that GPS coordinatrs with .2 foot accuracy require a level of data which is reserved for US military and government use. I believe that level of accuracy requires 24 digit GPS data and I think the only amount of data allowed to civilian use is 16 digit accuracy with the result of about 3 m accuracy. My understanding from my work in that field is that the reason for limiting that is that enemy forces could use that level of accuracy as a means of targeting with lighter, smaller weapons, were 3 meter accuracy requires a weapon with a much larger blast radius, thus using throw weight as the limitation on what kind of weapons someone would have available. Our use in Strategic weapons, of the accuracy we have (Had? But another story ) is what allowed development of the Cruise Missle's accuracy over multi-hundred mile terrain-following deliveries. It still facilitates a lot of our stealthier arrivals in SpecFor missions. We pay for the accuracy. Making it publically available is giving it to people who don't like us, and have stated they'd like to use it to hurt us.

Not so.

The Trimble Geo7 (and other brands) achieve cm accuracy, no military connections required.

You would probably need to subscribe to a corrections service to get there though.

Forget GPS. GPS accuracy is about 5 meters, much more than 0.2 ft., which is probably why there is no gadget that you can aim a beam and get a readout.

But that's OK, for your project, you just need relative accuracy, not absolute accuracy referenced to the center of the earth. You basically need a 3d model of your creek bed if I understand it correctly. There is software that takes multiple images taken from different viewpoints and melds them together into a 3d picture.

Check out 3d mapping software

5m accuracy for GPS may apply to phone GPS but surveyor grade devices regularly achieve sub cm accuracy.

It seems that you are considering development in the river channel (dry) and its impact on the flood lines. Determination of 50-year or 100-year flood line is specialist work requiring a topographic survey and numerical modelling.

Estimating the rise in the level of water flowing through the river channel is a very difficult task as it involves estimating the peak flow rate in 1 in 100-year events. Flow-through the river channel results from the collection of surface water over the very large surface area which is further impacted by other developments that could be far away from your proposed site. Surveying the site now, or waiting for next rainy day is not going to help you.

If this enquiry is for a commercial project I would definitely suggest that you employ specialists, otherwise try to follow below guide and see if you can perform some estimations;

The US Army Corp of Engineers (USACE) Hydrologic Engineering Centre River Analysis System (HEC-RAS) model calculatea the relevant flood levels for the 50- and 100 year flood events. HEC-RAS undertakes hydraulic calculations between user-defined, consecutive river cross-sections along the defined length of the river channel in order to quantify the backwater effects of channel variations and in-line structures.

Flood peaks are calculated for the 50- and 100 year storm events were used as modelling input to the HEC-RAS model. The flood peak events calculated represent worst case scenario floods; these assume events are distributed across the entire area of all contributing catchments under consideration. The model is able to determine the influence of various control points/obstructions such as bridges, culverts, weirs, and structures that traverse the water course.

https://dashboard.waterdata.usgs.gov/app/nwd/?region=lower48

Check out a software product called "image meter". It will enable you to add dimensions to photographs even if they are taken from a skewed angle and different height to the gully. To make it work in your application you need to project a vertical laser plane perpendicular to the line of the gully to highlight the correct position of the points to be digitized. Also mount a vertical 1metre square target next to the laser projector on the same axis as the laser line. Including the target in the image gives you an accurate size to scale the image from. Perspective makes the top and bottom edges of the target appear not to be parallel which gives you the angle off square that you are photographing from. Side edges of the target appearing not to be parallel gives the off height that you are photographing from. A zoom function aids with accuracy when scaling. The software then automatically orients the dimensions you apply to the image to take the scale and off angles into account. A GPS mounted with the projector gives the rest of the information you need. The software automatically works out areas and a virtual horizontal line drawn over the gully from the base of the target gives you a height and offset relative to the GPS location. A digital compass measures the angle of the laser plane relative to a map.

You can get cm accuracy with a modern, low cost GPS but you do need to read the details and do a little extra.

I wish I could remember exactly what the specs are for the county engineers in my area. I think it was something "unbelievable" like 0.05 ft vertical and 0.02 ft horizontal accuracy. But, they have both Government CORS data (NOAA Continuously Operating Reference Station) and local GCPs (Ground Control Points).

For many GPS receivers the accuracy values of 1m or 10m are still true. However there are receivers available (I bought one for about $250) that, if used properly can provide cm accuracy (or better).

Some of the things to take into consideration when comparing "old" vs. "new" accuracies:

1. Most of the GPS and other navigational satellites run somewhere around 1.2 GHz to 1.5 GHz. If the receiver only uses "clocks" then the speed of light and frequency will provide a hard limit on accuracy. If the receivers use "phase" then a dramatic increase in accuracy can be obtained.
2. If you are only dealing with 'the accuracy" of "the receiver" then many things including propagation limit accuracy. If you are talking "cm accuracy" then the propagation effects and orbital mechanics issues will essentially be the same for your "mobile" receiver as they would be for a "fixed position reference" receiver a few miles away. Since a "fixed position reference" receiver is not moving then its apparent movement due to propagation and orbital issues can be subtracted out of the data for the "mobile" receiver and if your goal is cm accuracy then the propagation and orbital errors effectively go away.
3. The sky is pretty crowded now. If data is collected from multiple US, multiple European and multiple Russian satellites at the same time then processing that data can produce improved results. it won't actually "average out' but it will improve.

There are quite a few Government run reference stations that provide CORS data. With either real time processing or post processing the CORS data is very helpful. Many state and local governments set up their own reference sites called Ground Control Points (GCPs). My county has numerous GCPs. A GCP 5 miles away is better than a CORS station 50 miles away.

The Emlid Company https://emlid.com/ has both professional grade receivers and low cost receivers used by the drone community. If you Google "GPS cm accuracy", "drone", "Emlid reach", "CORS", "GCP" and the other terms you trip across with these googles you will quickly have a hundred or more bookmarks on high accuracy GPS.

The main tricks for accuracy are:

1. The receiver uses phase in addition to clock cycles
2. The receiver uses multiple satellites
3. Either real time or post processing is done to utilize either CORS or GCP data for corrections.

A few starting links:

https://emlid.com/reach-rs-use-achieve-cm-accuracy/ cm accuracy

https://www.youtube.com/watch?v=Bb0HnaYNUx4 create a 3D terrain map

https://www.ngs.noaa.gov/CORS/ govt CORS

https://www.ngs.noaa.gov/CORS/data.shtml govt CORS

http://resource-analysis.com/geospatial/gps-collection-devices/ a reference page

Take a LIDAR image. 3D print image. Add water and measure where it goes. Demonstrate to permitting authority.

In the pre-electronics days, they would do this by simply constructing a low-level, rectangular-notched weir, with scales painted on the sides, so they could read the height of the water flowing over the weir to calculate the net-quantity, and then, the velocity of the water actually flowing, irrespective of the stream-bottom profile ...

That wouldn't work even back then. We need the calculated high water for a 25 year and a 50 year flood. The existing flow is immaterial. It would probably always be less than the 25 year flow. The volume is calculated by the area or water gauges for big streams. I'm interested in small drainage areas. The old Q=CIA will give me the flow rate. I need the cross-section of the stream bed to use Manning's formula to get the top of water elevation for a given flow. Getting the cross section without physically getting on the ground to measure it with level and tape is the problem.

Back then, they did not realize that they were also building small stormwater-detention-basins, and small aquifer-replenishment-reservoirs, all-in-one, at the same time...