Groundwater driven streams are thermally stable,
maintaining cool temperatures during summer months, which is particularly
important for thermally intolerant species such as trout. In addition,
groundwater fed streams show slow response to precipitation events, maintaining
a fairly stable discharge. Runoff driven streams show a "flashy"
response to storm events, with peak discharges far above mean discharge.
Between storm events, runoff driven streams are dominated by low flows.
A two dimensional graphical representation of
rate of groundwater delivery to the stream (based on the Darcy Equation,
which estimates groundwater flow based on hydraulic conductivity of the
soils, head pressure, cross sectional area, and gradient.) Again, the darker
pink/red areas are areas which have greater rates of groundwater delivery.
Lacustrine Clay and Silt
End Coarse Till
End Fine Till
Surficial geology of the catchment after Farrand's
quaternary geology maps. The main branch of the Au Sable between Mio Dam
and Alcona Dam flows exclusively through glacial outwash, with tributaries
originating in lacustrine deposits, ice contact/outwash, fine till, medium
till, and coarse till. The coarse material in the Au Sable basin
is very porous, so water infiltration into the soil is high. Porosity
and infiltration are factors which drive the groundwater system.
types in the basin
Au Sable River, tributaries, and impoundments
Outdoor Recreation Development
Aspen/Birch Dominated Hardwood Forest
Upland Pine Coniferous Forest
Forested Wetland--Mixed Forest
Au Sable River, associated tributaries, lakes, and impoundments