Set the first pole of the level, then stretch the other out to working distance and begin moving it in an arc downhill, watching for when the water reaches its highest level. Difference between the level mark and the water line is your elevation change.
Travis Johnson wrote:Peter, just wondering where you have tried to get contour maps. I am not knocking your method, I have used it myself in laying out logging roads on my farm, but I can get free 2 foot contour maps of even my distant, end-of-the-earth rural farm from my local Soil and Water Conservation District Office. They work with the USDA-NRCS which is privy to a lot of information and tools. Have you checked with them?
That 2 foot contour sounds like the LIDAR dataset. My area of Michigan is not covered by LIDAR. Best I've been able to find are poor resolution USGS topo maps with contour lines around 4 or 5 feet apart (the numbers don't add up when you count lines and read the elevations, it's kind of crazy). Believe me, I've spent a lot of time digging through the available material online, we were researching to buy land from 700 miles away, I wanted every source of information I could get my mitts on to make up for not being able to put my feet on it
Have you tried using the Web Soil Survey, man that has a lot of information on it. It is a bit goofy to use, but it was made by the US Government so it is going to be quite clumsy, but do an area of interest map and make a report and you will have 30 pages of information that you never knew existed. I have verified a lot of information on the Web Soil Survey (it is all free), and boots on the ground confirmed what I saw. In fact I have used it to lay out fencing for rotational grazing. Its so accurate it is great. I can sit in my PJ's and figure in rolls of wire and number of fence posts. The last time I did this I was off by (1) fence post too many. Not bad!
LIDAR is great because it is set by laser from satellites in space so it is very accurate, mostly because the topography has changed. A lot of people do not realize this but the contour maps of the USA have not been updated since 1900. Oh the roads and vegetation (fields versus forest) have, but not the contour lines. Erosion and water body elevations haven't helped with accuracy.
This is a serious issue in Maine because water body heights were changed at whim back then. In order to drive logs down the rivers, dams were built on streams and lakes to back up water for the Spring Freshets. They would take a stream you could step over and with dams, in the spring float 10 logs side by side down. In 1900 river driving was at is height so dams sprung up overnight and many stayed in place well into the 1960's. They leaked water, but they changed the elevation of the water bodies by a lot.
Here is the link to Web Soil Survey
I started this thread because it had occurred to me that while we have lots of discussion here about the use of bunyip levels and other tools for marking level contour, there's essentially no discussion about using any of them for measuring actual contour. The A-frame isn't useful for measuring the profile of a slope, but is good for marking level contour. Surveyor's transits and laser transits are both good for both level and contour profile measurements, but pricey.
Bunyip levels would appear to be the least expensive and lowest tech means for measuring contour profiles.
I actually love this sort of thing. Being a bulldozer guy I love building roads and swales, but do not do it indiscriminately. They have value and purpose, but take vital land out of production so it is best to really plan where they go getting the most out of every square foot.
I remember when I first came here there was a person that wanted to put a circular road on their newly acquired 10 acres. While I understand the need for access, they would have been better off to drive a road through the center with branches coming off it. The circular plan they had encompassed 10% of the land mass. They could have reduced it down to 4% with a little better road layout.