Hello! I have 2 problems. #1 At my house, the back of the property is about 30 feet higher than the front of the property. In the back of the property, there is a rock/cliff-face. When it rains, water rolls down here and rolls to the front of the property where there is a retaining wall. It then rolls off of there and onto the sidewalk, and then into a drain. The problem is, is that over time, the water has made a channel down the middle of the front yard. The channel is about 2 inches deep and 4 inches wide. It is just bare dirt. When I put grass seed on it, the next time it rains or the sprinklers come on, the seed is just washed down to the front. #2 On the other side of the house, the same thing happens but has a different effect. The grass is okay, but the space in between the mulch bed that goes down the property line and the grass fills with water during moderate to heavy rain and blows out all the mulch forcefully off the front retaining wall onto the pavement. What can I do about this? Thanks.