FLOOD09770

• Designation Number: 493
• County: Yuma
• Community: Yuma
• Stream Name: Republican
• Basin: Republican
• Title: Floodplain Information Report - Phase A Report - Yuma
• Date: 4/1/1976
• Designation Date: 3/1/1999
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Land usage is varied depending upon the soil type and availability
of supplemental water. The more hummocky or sandy areas are generally retained

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in native or somewhat improved dryland grasses for grazing. The cultivated
areas are cropped to small grains, corn, sorghum, and some alfalfa. With
the improvements in the center pivot sprinkler systems and the development

of relatively high yielding wells from the underlying aquifer that has

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occurred in the past five to eight years, a significant increase in

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irrigated land has been achieved in the general Washington-Yuma County

area. The increase in sprinkler irrigation has not materially affected

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the hydrological characteristics of the basin due to the controlled water

application rates and the relatively high infiltration rates typical of

the basin soils.

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The soil mantle infiltration rates utilized in this study are based
upon the tests and data accumulated by the U. S. Soil Conservation Service.
The soil survey for Washington County was completed and published in 1947.
The Yuma County soils survey has been essentially completed but to date
has not been published. However, the data for definition of the hydrological

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soil groups were made available to Hydro-Triad, Ltd. for this study.

Aerial photos supplied by Yuma County Land Use Adminis~ration and the

U.S.G.S. at ~kron have been used to supplement field surveys of vegetal

ground cover and land use.

The current land uses combined with the hydrological soil groups

were basically utilized as outlined in the S.C.S. National Engineering

Handbook, Section 4, Hydrology, to arrive at the runoff curve numbers (eN)

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