The flow of surface water runoff on the north side of our property is, for the most part, “sheet wash” drainage. Basically, the surface water runoff follows a relative flat plane (slightly tilted down to the southwest) until it meets a natural drainage depression, higher elevation or another drainage plane sloped in an opposing direction. Natural drainage channels commonly occur where two planes meet; the intersection of two planes creates a line. In our case, that line is a predictable drainage pattern north of our home that travels southwest toward a small creek that empties into the Chickahominy River (west of us about a 1/4 mile).
The soil surrounding the house has been built up over time to move surface water away from the house and foundation; runoff from the roof especially. Also, the soil behind the house (west of the patio) was disturbed during construction of our addition. The backyard was graded relatively flat subsequent to construction. The resulting drainage pattern is clearly visible now that a recent snow is melting; see the photos below.