FLOOD03016

• County: El Paso
• Community: Colorado Springs
• Stream Name: Arkansas River and Tributaries
• Basin: Arkansas
• Title: Areawide Urban Runoff Control Manual
• Date: 9/28/1979
• Prepared For: Pikes Peak Area Council of Governments
• Prepared By: Gilbert Meyer & Sams
• Floodplain - Doc Type: Miscellaneous

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PART V

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il

EROSION AND SEDIMENT CONTROL

A. Water Erosion

(-
I

Estimates of long term average annual soil losses from sheet
and rill erosion can be made through the use of the Universal
Soil-Loss Equation (USLE) as outlined in the Soil Conservation
Service publication, Erosion and Sediment Control in Urbanizing
areas of Colorado:

A = R(or El) x K x LS x C

where:

A = soil loss, tons/acre/year

R = average annual erosion index for the specific
geographic region (see Figure V-I)

EI

= the erosion index for a portion of the year -
- -determined as a percentage of R from Figure V-2

K = the soil erodibility factor based on particle
size distribution, organic matter content,
structure and permeability. Values of K for
soils in El Paso and Teller Counties are listed
in Appendix A.

LS

= the factor that accounts for length and percent
slope - See Table V-I

C = the soil cover factor - See Tables V-2 and V-3

This manual incorporates the SCS document described above
as the major technical element in determining needs and control
of water erosion. That document must be used in conjunction with
this runoff control manual. The Appendix contains other valuable
reference information.

In addition to the evaluation of long term mean soil loss
from sheet and rill erosion, sediment load carried downstream to
some point of interest is most commonly evaluated by use of a
sediment delivery ratio. This relationship defines the general
proportion of sediment conveyed via a drainage course downstream
after all local depressions have been ~illed in a given drainage
area. The relationship is shown in Figure V-3.

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