Chapter 2. Hydrology
31
Table 4. Precipitation and runoff characteristics for ecosystem provinces in the western U.S.
Dominant
Map
moisture Importance of
Vegetation
Physiographic
Character of
source
unit*
snowfall
density
province
Soil order
runoff
perennial yet
242
winter
spring runoff
high
Puget Lowland
Andisol
flashy
perennial yet
high except
Cascades
Andisol
M242
winter
high
flashy
above tree
level
high except
Coast Ranges/
Inceptisol/
largely
M261
winter
high
above tree
Sierras
Andisol
perennial yet
level
flashy
Entisol/
ephemeral to
262
winter
spring runoff
moderate
Central Valley
Alfisol
south; debris
flows
Alfisol/
ephemeral to
261
winter
limited
moderate
Coast Ranges
Mollisol
south
Entisol/
ephemeral to
M262
winter
moderate
high
Coast Ranges
Alfisol
south
summer/
Aridisol/
322
low
low
Basin & Range
ephemeral
fall
Entisol
winter/
lowmoderate
Basin & Range/
Aridisol/
341
moderate
ephemeral
summer
in mountains
Col. Plateau
Entisol
winter/
Basin & Range/
Alfisol/
ephemeral w/
M341
moderate
moderate
summer
Col. Plateau
Mollisol
spring runoff
Columbia
Aridisol/
ephemeral w/
342
winter
moderate
low
Plateau
Mollisol
spring runoff
Rocky Mtn/
ephemeral w/
332
winter
moderate
moderate
Mollisol
Great Plains
spring runoff
ephemeral w/
Rocky Mtn/
Mollisol
331
winter
moderate
moderate
spring runoff
Great Plains
Northern Rocky
perennial yet
M333
winter
high
high
Inceptisol
Mountain
flashy
winter/
Southern Rocky
Alfisol/
ephemeral w/
M331
high
moderate
summer
Mountain
Mollisol
spring runoff
winter/
Colorado
Aridisol/
313
moderate
low
ephemeral
summer
Plateau
Entisol
winter/
Basin and
Alfisol/
M313
moderate
moderate
ephemeral
summer
Range
Inceptisol
winter/
Great Plains/
Aridisol/
321
low
low
ephemeral
summer
Basin & Range
Entisol
winter/
315
low
low
Great Plains
Mollisol
ephemeral
summer
* same as in Table 2
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