swale specifics

Thank you, Mr. Lawton, for taking the time to answer all our questions.

Swales are essential, and I was wondering... how little can you get away with? Does the swale have to be X cm for it to work? Does total rainfall equate to swale depth or just max dump volume per large storm, mitigated by soil type?

What about dropping rocks in an on-contour row, to create a bermed swale with the help of detritus from runoff -- would that work? What about swales or stumps inside a the bermed swale to assist with permanence?

Mulching a swale helps reduce evaporation, but is that assistance offset by the swale filling in with OM and needing to be re-dug (ug!)? What's the best way to dig out a swale? How does one deal with swales on a slope, where the ends of the swale are dictated by others' property?

I'd like to chime in too. Are hugelkultur swales significantly better?
Which plants would get more moisture, three feet uphill from the swale or three feet downhill? I don't imagine planting a tree right in the swale would make good sense.

Greg Harvey

This guide goes a long way towards answering many of your questions:

http://permaculture.org.au/2010/12/15/a-guide-to-back-flood-swales/

It has really good diagrams, explains calculations on swale spacing and cross-section, how to dig, how to design overflows, etc.