Appendix
A.
Highly
Erodible Soils
Big
Darby
Creek
Headwaters Soils – Map A-1
The erodibility of soils in this watershed are largely
controlled by the Powell Moraine in
Union
County
and slope in parts of
Champaign
and
Logan
Counties. The line of highly erodible soils
(red areas) that sweep through
Union
County
marks the edge of the Powell Moraine and steeper slopes approaching
Big
Darby
Creek. The soils associated with the
Powell Moraine are composed of clayey soils that are more susceptible to
erosion. The soils in
Champaign
and
Logan
County
have considerable amounts of highly erodible soils largely associated with
steeper slopes than the other parts of this subwatershed.
Approximately 14.2 percent of soils, the most of four subwatersheds, are
highly erodible.
Middle Big
Darby
Creek
Soils – Map A-2
Soils in this small watershed, approximately 50,000 acres,
are in the heart of the
Darby
Plains
soils which have less clay than those in
Union
County. Slope near
Big
Darby
Creek
is the major factor contributing to the few highly erodible soils in this
subwatershed. Over 77 percent of the
soils in this watershed are not highly erodible.
Little
Darby
Creek
Watershed – Map A-3
This watershed begins in the sloping regions of
Champaign
County
and then flows through the flat portion of
Madison
County
into the
Big
Darby
Creek
in western
Franklin
County. The soils in the Little Darby
Creek Watershed in
Champaign
County
have a considerable amount of highly erodible soils because of steep slopes.
The remainder of the highly erodible soils in the county remain within
the sloping regions of the stream corridor.
Lower Big
Darby
Creek
Soils – Map A-4
The
Lower
Big
Darby
Creek
soils begin to slope more than those in the central portion of the watershed.
Slope is the major limiting factor for the erodibility of soils in this
watershed. About 45 percent of soils
in this watershed are considered either highly erodible or potentially erodible.
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