I would like some feedback on an idea I'm playing around with (and I'm sure this isn't a new idea). On another thread I was informed that hugel beds are not good on contour since they then become a dam and can break down.
Here's my idea: Place the woody material partially below grade (let's say 1 foot) and partially above (maybe 2 or 3 feet). Put a swale on the uphill side with a level sill which doesn't allow the water to get above grade. I'm thinking since the water never gets above grade, then all of the loose wood material below grade is supported by the solid ground on the lower side. The water will soak into the bed from the swale and saturate all of the woody material below grade and then wick up to the plants which are all planted above.
My main question is will this design support the water damming and not break down the woody material?
I've attached an image which hopefully helps understand what I'm trying to describe.
I've attached another image which shows how the water would move down the spill ways. This sketch is very rough and in reality I would probably stagger the spillways so that it would help fill the swale below it rather than just running away.
My understanding of swales is that they work best as a system for growing trees and hugelkulture is a system for growing plants and shrubs. That being said you might want to think about a layout with your swale and berm and then a walkway maybe five feet wide then the hugels as you discribe. I think with a layout like this you would gain all of the optimal functionality of both systems working in harmony. Your swale would still provide ample moisture to your hugel and you would stand very little chance of it washing away. Just my thoughts, for what they are worth.