ABC: Slow, Spread, Sink it


There are many ways we can slow, spread & sink water in the landscape, in order to re-hydrate & ensure we don't let this valuable resource turn into a major erosion factor.

Swales






Contour-level Tools

from Permaculture in Brittany
We used the A-frame to mark out the contour and then, when I’d dug out the swale, I hammered in pegs of wood and used a 2.5 metre straight edge with spirit level to check the level of the bottom of the ditch (see photo). 


Ultimately, the most accurate way of checking your swale is level is to look at it when it first fills with water. 


The surface of the water will always be at the same height, so if you have a reasonably even puddle the length of your swale, you’ve surveyed and dug your swale well. 


You can adjust the swale after it’s rained, so it really is quite easy to get it spot on




A-Frame

from Permaculture in Brittany


The idea of an A-frame is that the two legs of the triangle are equal and a line with a weight (plumb line) hangs off their intersection. The connecting bar, attached at the same point on each leg, is marked at its centre. 


When the plumb line cuts the centre mark, the two legs are at exactly the same height. 
We use this property to walk the A-frame across the land, shifting the moved leg up or down the slope until the plumb line shows they are level. 


We then mark that point and swivel the other leg around, repeating the levelling, and so on, leaving a line of pegs that mark out the contour. 


One problem with the plumb line is that the bob swings like a pendulum and takes a while to settle, or needs a partner to steady it at the bottom. 


We got round that by attaching a spirit level at eye height on the crosspiece, whose bubble settles quickly, so speeding up the process. 


Photo shows Gabrielle using our A-frame.





Bunyip Water Level

from Permaculture in Brittany
Water will find its own level and the Bunyip exploits this. 

You get hold of a transparent length of pipe and almost fill it up with water, so you can see the level of the water a little bit down from the end of the pipe. 
Wherever the ends of the pipe are, even out of site of each other, once the water level has settled, it’s at exactly the same level, both ends. You need somebody on the other end of the pipe. 


When you move the pipe, both of you clamp your thumbs over the end, to avoid spillages. When you’re in position, you need a little coordination to get approximately the right level. 


Release your thumbs—lots of shouting is in order—and if the level races in one direction, thumbs on quickly and one of you adjust up or down accordingly (try it and you’ll see, an error says a thousand words). 
With a little patience, you will get the hang of it 



Video - how to make a Bunyip
Step by step Process of how to build and fill a water level




Laser Auto Level Kit

what professional surveyors & topographers often use, and if you have the kit, it has its advantages for earth-works
(and dis-advantages)





Water Movement Into Aeration Holes

This is a clip from the classic Water Movement in Soils made by Gardner & Hsieh at Washington State University in 1959. It shows how water moves easily into an aeration hole that has been filled with sand, but that when the aeration hole loses its connection to the soil surface, a hydrophobic condition may occur.




Subpage Listing


Comments