FLOOD04800

• County: El Paso
• Community: Colorado Springs
• Stream Name: Cottonwood Creek
• Basin: Arkansas
• Title: Engineering Study of Cottonwood Creek Drainage Basin
• Date: 8/7/1979
• Prepared For: Colorado Springs
• Prepared By: Lincoln Devore
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Much of the upper basin thus tends to reduce flow in the main streams.

Conversely, the basin contains a number of swampy areas. This is

particularly true of the western portion of the basin. In these areas,

the sands and silts are closely underlain by less pervious soils -

clays, dense silts or sandstone. The topography of these areas is

usually such that water can enter more rapidly than it can leave,

The less permeable material lies relatively flat, at the general

formation dip, while the upper terrain is eroded at a steeper slope.
The surface soils in the western,

closely studied, portion of the basin were mapped by three methods.

Records of test borings drilled throughout this part of the basin

were studied and plotted. The surface soils were studied in a field

reconnaissance, and study of air photographs flown in 1942 and in

1978. The results were plotted over the entire basin since soil type

and condition have considerable effect on the final runoff. This

plot was compared with soil types mapped by the SCS in its survey

of El Paso County surface soils. The correlation was fair. The

SCS survey is rather generalized and with far too much dependence

on air photo interpretation for good, spot correlation. In this

basin, the correlation was found to be better than usual.

The overall geology of the basin and

the soil types noted near the surface in the area will produce runoff

which is relatively low for the basin area, Infiltration is relatively

high throughout the basin, but particularly in the north and east.

The western portion of the basin, being considered more fully devel-

oped, will produce higher local runoff.

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