FLOOD05505

• County: Gunnison
• Community: Gunnison County
• Stream Name: Gunnison River, Tomachi Creek
• Basin: Gunnison
• Title: Floodplain Information Report
• Date: 12/1/1976
• Prepared For: Gunnison County
• Prepared By: ECI
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

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The variation of the quantity of the peak flood ~ithin the
study reach wll.$ studied. From this analysis, it ",as concluded that the
runoff yield during periods of peak flow from the low IyinK areas is
small. This result supports the conculston that snowmelt from upper
elev1lUona is the "'''jor contributor CCl chepesk flows.

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A detailed analysis of the precipitation data was conducted to
determine its impact on peak flows. Examination of precipitation data
revealed that frequently s number of stations did not record any pre-

"ipiratinn during the peak runoff periods.

Further, that precipitation

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was not widespread over large areas du~ing the same periods. Only
during the years 1960, 1964 and 1973 appreciable precipitation over
widespread areas was recorded upstream of the study area. These periods
of high and widespread precipitatioa did not produce high frequency peak
runoff at Gunnison and Tomichi Creek runoff measuring stations located
in the study area.

Generally speaking, the mOre productive streams of Western
Colorado have experienced large peak runoff rates during years of high
temperature combined with snow packs with high water content. An
exception to this has been the San Juan Mountains areaS where rainstorms
have known to produce peak flowa.

A detailed description of the hydrologic analysis and the re-
~ults ohtained thcrcfro~ is included in thc Tcch~icnl ~ddcndum.

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