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Help: suggestions for figuring out contour lines  RSS feed

 
Posts: 33
Location: Portugal
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Hi all!

I'm planning some swales in one part of my land, but even thought the land is quite flat, I'm having a hard time figuring the contour lines.

I've tried A-Frames(too slow for a big land) and bunyip (needs 2 people to operate, but I'm alone doing this).

I'm considering getting some professional gear, but a quick searched revealed equipment priced at 3k or higher :o

Any clever suggestions on how to go about this?

Ideally, I'd love a tool connected to gps, so that I can also make a digital map of it, for planning purposes.

thanks in advance!
 
Posts: 483
Location: Bendigo , Australia
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There is a simple way.
Get say, 100M of clear tube, or at least tubing with say 2m of clear at each end- 3/8 inch internal diameter.
Attach solid poles to each end, 4 feet long, say 1 inch across, one with a pint so it can be driven into the ground.
Mark both poles 2 feet off the ground as a level for the water in the tube to rest at.

Have a spray marker or more pegs available to mark the ground as you move about.
Start at one location with the pointed pole driven into the ground so its stable.

Then walk around with the other end and place it on the ground where you think the contour is the same as the start point.

Move around a small area until the water level hits the marked point.
Mark the ground, then move another say 20 feet distance and repeat.

when you have reached the end of the tube, move back to the start point, and move the pointed pole up or down the slope, if its steep move say 5 feet
if its flatter land, move say 20 feet and repeat the steps.

If you use different coloured markers or posts for each contour when you have finished, the contours will be easily seen.

Create a flat board table with a map of the area on plain paper.

Then using the flat board table, mark straight lines with a rule showing view lines to each peg around a map picking up each peg on each contour. write the peg Identifying number at the end of each line.
Depending on the size of the area, move the whole table say 400 ft on say 10 acres and again mark the view lines, noting which peg you are work with and where each peg view lines cross that is the position of the peg on the map.
At the intersection write the Peg ID number.

using your water line with a ruler attached, you can work out the vertical height difference between each contour.
BUT REMEMBER if you ensure each contour is started at a known difference in level from the start point, contours are easily obtained at what ever interval you need.
Identify each peg location with the same colour as the one used to identify each contour

If you also mark lines to gateways , big trees etc around the paddock you are working with , all features on the landscape can be located easily on the map. IE Dames, piles of rock etc, buildings.
 
Posts: 30
Location: Australia, New South Wales
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My original quals were Surveying - There's two accurate ways to accomplish what you want:

1. Hire a dumpy level, tripod and range pole and plot the points with a tape - old school.
2. Hire a theodolite total station and do the same - the modern ones will track as you walk, give distance, bearing, height and coordinates. The information is downloaded into an electronic field book that can be plotted.

Alternatively, hire a Surveyor to do it.

The second choice will provide hyper accurate results theoretically to the millimetre.

It depends how accurate you want it done. If the site is 'level', then you may be looking at high accuracy to pick up the small changes.
 
Posts: 223
Location: Northern New Mexico, Latitude:35 degrees N, Elevation:6000'
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I purchased a Topcon RL-H4C rotary laser level a few years back for just under $700, I also needed to purchase a tripod to mount it to and a telescoping rod for the receiver, which was a little less than $100 for the two.  There is no GPS capability, but that's not something I knew existed, so I have no suggestions for them or experience with them either.  I like to print maps and draw my layouts with color pencils instead of using the computer, but GPS capability may possibly be easier.  I've seen kits for the different rotary lasers that includes all you need for around $500 and less, but there's something to be said about making a purchase once for a quality item.

I settled on the model I have because of it's quality, and it's performance.  The battery's last a long time, I just looked it up and it says they last 100 hours, it has a 2600' range, and a 5 year warranty.  I also purchased some 10000mah nimh batteries with a charger, I haven't kept track of how long the charge lasts with the larger batteries, but in almost three years of using it I've only charged the batteries once, about a month ago, and the same with the receiver batteries....though I don't use it every single day, or even every week, or month.  But when I do use it, I have it on all day.  I've been quite happy with it.  It makes it very easy to get work done.  The bunyip in very dense trees would maybe be a little easier with a very long tube, but I haven't needed to use it in such an area so I can't really say.

I don't know why the equipment you were looking at was so expensive, maybe because of the GPS??  But even if you needed to have a rotary level shipped from a different country I can't imagine it costing that much more....though I really don't know.  The model I have can be found on a lot of websites, it's fairly popular.  I purchased mine from amazon.

Maybe you can rent the gear if you don't need to own it?  Though if you have a large piece of ground you may need to make multiple rentals over time which may add up to the same cost as owning it?

I don't have any clever suggestions, I just wanted to give my opinion/experience.
 
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Having gone recently through land surveys and made A-frame, and bought a cheap chinese laser-level (around 50usd from a company called rowel), I have to admit that the laser was the right investment. It has to be usedin early morning or early evening, but itis readable up to 50mtrs. One of the surveys was so difficult because the land was so uneven due to previous agriculture tilling etc, that I ended up using trees on the site to get the elevations. For assist I taped an old measure tape onto a pvc pipe with a T-joint on the bottom. It is easy to find the laser on that tape. For reference I took the nearby road elevation from google-maps.

Hope this helps
 
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