FLOOD06193

• County: Alamosa
• Community: Alamosa County
• Stream Name: Rock Creek, Gato Creek, Zapata Creek
• Basin: Rio Grande
• Title: Report on Hydrologic Investigations FIS Alamosa County
• Date: 12/1/1975
• Prepared For: Alamosa County
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Floodplain Report/Masterplan

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There was no distinct separation between the two curves. The results

were not considered indicative of flooding potential of the basin.

Insufficient streamflow record and the location of the gage were con-

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sidered responsible for these results, Since results were not indicative

of ,the entire area and were ~nreliable, flow frequency parameters were

developed from "Manual 'for Estimating Flood Characteristics of Natural-

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Flow Streams in Colorado" by the u.S. Geological Survey. Equations for

computing the lOa-year and la-year floods as developed for the Southern

Plateau Region of Colorado were used and are as follows:

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Q ~ 59.7 AO.709
10
Q ~ l03 AO.710
100

where Q is the lO-year peak flow, Q is the lOa-year peak flow, and
10 100
A is the drainage area in square miles,

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There is no streamflow record for Zapata Creek and tributaries, It was

therefore necessary to do,a regional frequency study to develop basic

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discharge frequency relationships, Since flows from the North Zapata

Creek, Middle Zapata Creek, South Zapata Creek, and tributaries are pre_

dominantly caused by spring snowmelt runoff, sixteen stream gaging

stations reflecting snowmelt runoff in the Rio Grande Basin were selected

for frequency analysis, Discharge frequency relationships for each sta-

tion were computed by methods outlined in WRC Bulletin 15,' The lOa-year

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