I am new to permaculture and this site so forgive me if I step on any toes. As I understand the purpose of permaculture is to work with nature not against it. However, every hugelkultur mound I have seen built here or diagrams is against how nature builds mounds that would work as these are desired. Nature does not build high to begin with or so vertical. IN nature a tree might fall across a hill contour that is then filled in from above by leaves and erosion. The log serves initially as a dam. With time the back side may start to have some build up from leaves and then overflown erosion. Over time the uphill side will fill slowly until a swale is formed above the log. During this time soil creature move in and seed is sown, whose root begin to hold the swale in place. Over much time the log will rot, but only after the swale has been established with growth to hold it in place. Build your hugel with this in mind, keep it low 18 to 24 inches maximum, filling up hill and sowing first deep root grasses like rye, wheat, millet and such. Then even deep rooted vegetables. Carrots will grow a root network up to 7 feet wide and as deep as 17 feet! Look it up. Nest add deep rooted bushes like seaberry, Fig, Grape and others and nitogen fixing trees with deep roots like American Red Bud and Honey locust. Then you will have a stable hugel (hill)/Swale. If you want something as tall as I see in your pictures and diagrams, make a tall raised bed as I do using cinder block as the walls and then put in the layering of various organic matter like limbs and other compostable each layer with dirt.
If you want a swale to hold on a hill without using wood or even with wood, scalp the sod first and layer it upside down as your build upward and it will hold. This is how I have built swales all my life in the East Tennessee mountains, only we did not know to call them swales, just erosion barriers and water diverters.
"In all things consider the lilies in the field, and birds of the air" though to many a biblical fantasy, Nature is there to provide for them AND to TEACH us!
