The busier downtown areas are built on the hillside, where flooding is less likely (*but still possible, I've seen water on main street before*), and the river basin is populated mainly by farmers. The city of Duvall has made many efforts to improve flood conditions. Woodinville-Duvall Rd. was rebuilt after the terrible flood of 2006, when most of the residents of Duvall were housebound (or shelter-bound) and without power and other services for two weeks. The rebuild of the road included a much higher bridge, however, you still have to cross the valley to leave town. The city of Duvall is surrounded by rivers on three sides, The Snohomish, The Skykomish, and the Snoqulamie. Generally, when any portion of the river system floods here, it floods the entire basin. This includes Duvall and the neighboring towns of Monroe, Carnation, Fall City, and Snoqualmie. The valley in Duvall is quite expansive, and when it floods, it looks like an unimaginable amount of water as it devours the entire valley. Sometimes seagulls show up to prey on the fish (I'm guessing that's why they're there).
Duvall is known for being a safe place that is "out there". A cursory glance at a map will show you that the area is, indeed, pretty isolated. This town is one of the few remaining that towns that you could sleep with all your doors unlocked and your car open with the key in the ignition, not that I'd recommend that anywhere. Duvall is home to many local farms, and has a surprising number of (family-oriented) recreational activities considering the size of the town.
The landscape is lush and green. The valley is open (that's the floodplain) and the hills are heavily forested in a way that only western Washington can offer.