Beginner Gardening: Drainage, 1 by sissyo

sissyo wrote:
We get the drainage from several houses above us & our yard slopes particularly on the lower end. It starts to level off about 1 house below us. The builder also graded our lot so the water flows away from our house so we have drainage from both directions. I can not impend the flow according to city rules. I put in evergreens along the fence for privacy. We created a ditch with rocks & lined both sides with 4x4's. I then tried to level the flower bed on the house side of the ditch. My problems is it keeps washing my mulch & top soil down hill. On the lower end it actually washes the dirt from under the shrubs I have planted. I have already spent a great deal of money but I still have the problem. I am at a loss as to what to do. I have included a picture I made in 2007 just after we finished planting the beds.