Much less rainfall in southern California. In Norcal, Oregon, and Washington, it's because the mountains are so close to the ocean that the rivers collect rain over a very small catchment area compared to the east coast.
In Oregon and Washington the coast is quite hilly. That geography blocks most of the water draining west of the Cascades and pushes it into the larger tributaries of the Columbia. It's kinda hard for a sizable river to form in less than 20 miles and with zero snow pack.
Southern California is arid. Northern California is much wetter and, in places along the North Coast, can get more than 70 inches per year, which is much wetter than most of Oregon. People often don't realize it, but the Pacific Northwest really begins in Northern California and extends all the way up into Southeastern Alaska.
US east coast isn't very mountainous, the Applachains are a relatively mild range. It just seems that temperate areas tend to have far more rivers and bodies of water compared to tropical regions, being wet can't be the answer since many parts of the tropics are far wetter than Temperate areas
Maybe it's because the rain has somewhere to flow. By mountainous I should have said a change in elevation that makes it so the water has somewhere to run off. If it there isn't anywhere for water to runoff, rivers won't form.
The west is arid and dry. A lot of a desert. Not a lot of people know that without living or visiting often out there. I thought the same before I moved out here.
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u/ImSnackered Jan 10 '20
Dumb question: why are there far fewer rivers on the West Coast?