FLOOD08228

• County: Boulder
• Community: Boulder
• Stream Name: Boulder Creek
• Basin: South Platte
• Title: Urban Drainage and Flood Control District
• Date: 3/1/1990
• Prepared For: Boulder Creek
• Prepared By: Goerge V. Sabol
• Floodplain - Doc Type: Flood Mitigation/Flood Warning/Watershed Restoration

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Rainfall Losses

Hydrologic Design Manual
for Maricopa County

Table 4.5
Published Values of Uniform Loss Rates

Hydrologic Soli Uniform Loss Rate, Inches/hour
Group Musgrave (1955) USBR (1975)1 USBR (1988)'
(1) (2) (3) (4)
A 0.30 - 0.45 0.40 0.30 - 0.50
B 0.15.0.30 0.24 0.15 - 0.30
C I). oS- o.ee-: 0.15 0.12 I),Oj"- 0 g .95- 0./4

J) C7 - O,t7~- I),,, 8
1 Design of Smaff Dams, Second Edition. 1975. Appendix A
2 Design of Smaff Dams. Third Edition, 1988

0-0,00

~';' Procedure for Estimating Loss Rates
j:2:~{.*1>::,~
MfMitf.
415:11 Green and Ampt Method
A. When soils data are available:

1. Determine the soil texture classification. Soils reports such as those of the
Soil Conservation Service can be used if available, or laboratory analysis
of appropriate soil samples from the drainage area can be used if adequate
documentation on the sampling and laboratory procedure is provided and
approved,

2. Estimate the hydraulic conductivity (XKSAT) for bare ground from Table
4.2 if general soil texture classification is available or from Figure 4.3 if
adequate soil texture data is available from an approved sampling pro-
gram.

3. H desired, adjust the value ofXKSA T for the influences of vegetation cover
using Figure 4.10. .

4. Estimate the wetting front capillary suction parameter (PSIFl from Table
4.2 if general soil texture classification is available or from Figure 4.4 if
adequate soil texture data is available from an approved sampling pro-
gram.

5. Estimate the value of DTHETA from Table 4.2 if general soil texture
classification is available or from either Figure 4.8 or 4.9 if adequate soil
texture data is available from an approved sampling program. The value
of DTIiETA must be selected based on the appropriate antecedent soil
moisture condition: "Dry" for nonirrigated lands such as desert and
rangeland; "Normal" for soil that would be expected to be near soil
moisture field capacity such as irrigated lawn, turf, and permanent pas-
ture; and, "Saturated" for irrigated agricu1turalland.

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