I think one area where engineering/landscaping/permaculture can intersect is
in bioengineering, i.e. the use of trees and other vegetation to stabilize
slopes and prevent erosion. Engineers doing earthworks along highways
should become more aware of the possible use of bioengineering solutions.
The use of vegetation to stabilize slopes can cost much less than hard
engineering solutions like retaining walls. I would like to see this kind
of work become more professional in nature so there can be designers and
contractors who are specialized in this. In the tropics bamboo and vetevier
grass are often used to prevent landslides on steep slopes, but someone with
more knowledge of the succession of trees can plant a more diverse system
which will reach a stable state and give protection from erosion a lot more
quickly. I think this is an area that needs a lot more research and
development.