All ya All ………I have a pond that is 2,711 ft around the shore line, I would like to determine the number of acres that the flat surface covers. I contacted 9 governmental agencies that deal with land mass and none could give me a formula to do this,3 of them said calll back if I find the answer ,I will and tell them it came from B.T. ……thanks a bunch!!!
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IF this circumference is a perfect circle, all you need to do is plug into formulae for circles.
If not, you have not provided the information to determine the answer. A kidney shape will have far less surface for the same circumference.
Excellence is its own reward!
There are 43,560 sf/acre. Like Piffin said we gotta know the shape.
I had a similar project in a computer/math class, if you can get a picture of the entire lake from above and have something you know the lenght of such as a boat for a reference of scale it's possible with calculus to get very close to the actual size.
can't remember the names of the programs we used though.
Never be afraid to try something new. Remember, amateurs built the ark, Professionals build the Titanic.
The most it could be is just less than 13 1/2 acres, which is a circle. A sample kidney shape is around 10 acres, and a square 10.5, but it could literally be anything less than the 13.42 of a circle.
Edit: You got the location on terraserver? Could get the shape from there and come pretty close by scaling it in CAD.
Edited 5/29/2003 12:13:16 AM ET by Cloud Hidden
I used to know this one...let's see...first you drop a BFR into the pond, then measure how much water was displaced...that will give you the cubic volume of the rock. Then...wait a second...maybe maybe you need more than one rock for this...
Jim,
You've got the wrong question. He wants to know the surface area. not the volume. WView Imagehat he needs to do is pour a quart of Valvoline on the lake and then measure the thickness of the film and then do the appropriate calculations.
To original poster,
But seriously, I have done just that. Basically the process is to draw a map of the pond on a sheet of graph paper with the little, light blue squares and then have one of your kids count up the number of squares. Or you could use a planimeter.
As for the basic surveying - I notice that you did have an exact figure for the circumference - how did you do that? One of those wheel things? How far across is this lake? What I did was establish marked points around the shoreline, say every 50' and then establish a series of triangles across the water. You may need a helper for this and the tape may get wet! So you get A to B is say 49 feet and across the puddle is point R. Then you measure A to R as 70' and B to R as 92'. And ye write this all down in yer Field Book. And you do that all around the pond till you've got it done.
And you can deal with the vagaricies of the shoreline by offsets in which you lay out your long tape - again 49' from B to A and do your offsets. At 10' the edge is 3' to the left or east and at 20' it's 5' to the right or west and so on.
And then you transcribe all this to your sheet of graph paper. You may need a beam compass and an architect's or engineer's scale. You can hopefully get this stuff at an art supply or office supply store.
Note: you could also use a builder's transit - not level - which has horizontal circles.
What is your latitude and longtitude?
~Peter
This message has been transcribed for your protection. Not responsible for typical errors. 99% sodium free. This message uses only genuine organic pixels.
Check out your local USDA/ASCA office. (United states Dept. of Agriculture)
They keep photos taken at specific altitudes so that the photos can be scaled.
They inventory by scale the acreage of wood, pasture, tillable, and impounded water surface areas. They also have printed materials on lake management.
The services are no charge.
.......................Iron Helix
Edited 5/29/2003 5:39:16 AM ET by Iron Helix
If the pond has been around for more than a few years, it will show up on a USGS topographic map. Get the smallest scale map you can, which will probably be a 7.5 minute map (1:26,000 scale). A local map store should have them, or you can probably order them online.
I think a map of the lake is a must. You can't do without it since it has an irregular shoreline. Unless you can approximate it's shape (or shapes if you can break it down) then you'll have to do as described by some of earlier posts. However, there's also another method which could be used for highly irregular shorelines which may also be populated by numerous land masses within it. It's called the Monte Carlo Method and relies on statistical probabilities. It still requires a map though. If you say draw a square around the lake which is large enough to contain all of the lake, then you essentially generate random coordinates (via a random number generator) and determine if the coordinate generated lies within the lake. Call that a hit. Those randomly generated that don't lie within the lake are misses. The ratio of hits to misses will determine the percentage of 'lake' that lies within the square perimeter (or even rectangle). Of course, you'd have to generate enough random coordinates in order for it to have some accuracy. How many that is for it to be statistically accurate I'm not quite sure, but it might beat counting tiny squares on a map. I'm surprised the people you contacted weren't familiar with this method. Unfortunately, I don't have the book on hand that suggested the method. I'll check when I get to the office. Anyway it might be an easier method if you do locate a map without having to grid it up. But you might be spending an equal amount of time checking generated coordinates, the more generated the more accurate.
All you need thereafter is the random coordinate generator which you might find online with some luck. HTH.
>It's called the Monte Carlo Method
I was headed in a comparable vein--using math and mins and maxs and sampling shapes instead of grid locations. I was trying to bound the problem by finding a max and a likely min (for example, we can be pretty certain the whole thing isn't a squiggly 1' wide canal, which would be approaching the theoretical minimum. Unless it has fjords like Norway, it's going to be some amorphous shape approaching the space of a kidney. Maybe a little more, maybe a little less. Depends how close he needs the answer. If it's just for giggles, call it 10 acres, or 12 if ya wanna brag, or 8 if it's taxed.
All.....Having gotten through 11th grade Shop Math I thought this was a an easy question with a simple answer .The method I used was to take the 2,711ft of shore line make it a square of four equal sides of 677 ft , then take length x width for a total of 458,329 sq.ft and then divide by the known number of 43,560s. ft. in an acre and came up with 10.52 acres. All was going well until I mentioned this to friend and he said "no way is it that big" ,went back and really looked at it and compared it to known land area and me thinks he is right.
After talking to a lot of people and my learned people here at Breaktime ,It somehow doesn't seem that important any more....The fish are biting , the beer is iced down and I got some ham sandwiches and your ALL welcome to come and be at peace . Maybe we can ponder the great questions of the universe and somebody can tell me how big this damn pond is .....:)
Offhand I'd say your friend is right - A wandering shoreline won't have the same area inside that a square does. The shape isn't as "efficient".
Where is your property (generally speaking) ?Better to live in the desert than with a quarrelsome, complaining woman. [Proverbs 21: 19]
Easy way is to put a sheet of graph paper in your printer and print out a topographical map of your pond from one of the online map services. Then count the number of boxes you have in your pond, and estimate the partial boxes. Look down at the scale of the printed map to figure out how big each box is, and you will have your answer.
Try the TopoZone service. They have pretty detailed maps for free. Here is a link to a pond in Virginia that sounds like it is about the same size as yours.
http://www.topozone.com/map.asp?z=17&n=4314053&e=752079&s=25
Use the name search feature and the 1:100,000 scale to locate your pond, then switch to 1:25,000 to get a more detailed image. If you use graph paper with the tiny boxes, you will have an easier time.
Good luck with whatever you end up doing.
Probably more commentary than you'd ever guessed. As extension or alternative to Monte Carlo method you could take your map of land and enclose a rectangle around it. Color the lake area a dark color. Scan it into a computer. Bring up the image in perhaps a photo editor. The photo editor (or similar program) can probably tell you the percentage of area the lake (colored by you) occupies within the rectangle. Since you know the area of enclosing rectangle (with appropriate scaling taken into consideration of course) then that area times the percentage of lake equals the square footage.
I'm too cheap to have sprung for a digital camera and the photo editor as yet to be able to verify above photo editor program but I'm sure you must know someone who's into that sort of thing.
Otherwise, guess the square footage and use these posts to describe to your friends how little people have to do to otherwise occupy their time.
You could get the picture you need of the lake from the terraserver. They're already ortho-rectified. Note the size of the pixels in the image, for instance the one I have of my neighborhood uses pixels one meter square. Then pull that picture into Photoshop, and put a colored overlay on another layer tracing the shoreline, then fill it. Dump the overlay only out as a .BMP file, and use Debug with redirection to a file to get an ASCII hex dump of its contents. Strip away the header, and use something like PC Type to reformat it to one pixel per line, then sort it into lake and non-lake pixels. Delete the non-lake pixels, and the line count is the number of pixels in the lake. Multiply by the area of a pixel, and that's your answer.
-- J.S.
USDA soil and water conservation service will have soil servey maps . arial photos of most of your county. You could get a map set at 660 ,they have a clear plastic device that has dots that represent 1/10 of an acre lay that over your map count to ten that is an acre . Also the guy at soil and water should have a little wheel that will run the circ. of the pond and a formula that will translate that into acres.
I think the first thing to do would be to invite me up there to go fishing and help measure the thing................(-:
Q: What's the quickest way to get into a blonde's pants?
A: Pick them up off the floor.
I'll bring some beer, maybe you could call it "Hog Fest, Fishin & Measurin '03".
Experienced, but still dangerous!
"I think the first thing to do would be to invite me up there to go fishing and help measure the thing"
So does that mean the pond will double in size by the time you get home?
Mike
It's O.k. to think out of the box, Just don't walk off of the plank!
AND will have put up a mean, vicious fight culminating with him being pulled into said pond and almost been made part of the foodchain(with scars to prove it).Life is too short so eat dessert first, especially if it happens to be Cookingmonster's triple cinnamon truffles or her ginger-fig caramels.
Whats the temperature ?
Is the ice still floating, or has it sunken yet ?
I'm afraid there is no easy answer for this.
You are simply going to have to go out there to the lake with a cup. Dip the lake out, one cup at a time, measure the surface area of what you have, then empty the cup and do it again.
You can't just measure once, and assume it will be the same every time. You won't always get the same amount of lake into the cup. You'll have to measure every time, and when finished, average it out.
Tedious work, yes. But there is no other way to be really accurate.
Besides, think of all the fish dinners you'll have, once you get down near the last of the lake.
A good heart embiggins even the smallest person.
Quittin' Time
This is off subject, but PM22's response about the Valvoline oil reminded me of a PBS show I saw years ago called Connections. Some 16th? century scientist put a drop of oil onto a pond of known size and after observing that the oil eventually covered the entire surface of the pond calculated the the thinness of the film thereby disproving a theory as to the smallest possible size of an object/material.
A really great show if you happen to see it. Somebody track down that James Burke dude and he'll tell us how to measure the surface area using the Valvoline method.
Buy a few hundred sheets of styrofoam insulation. Start laying them on the water. Get it all covered up nice and tight. Cutting sheets to contour of shore. Number of sheets used (best guess on cut sheets) times 32 sq. feet.
Rich Beckman
Another day, another tool.
That sounds like as much fun as trying to round up a herd of cats in a tuna fish cannery.
;).
Excellence is its own reward!
"That sounds like as much fun as trying to round up a herd of cats in a tuna fish cannery."
Exactly!! LOL!!
Rich Beckman
Another day, another tool.
laser inferometer, 1 qt, all solved, QED
Don't forget to allow for al the oil that gets stuck to all the wild life