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<br />tributary basin is narrow, composed of highly erodible clay loam
<br />soils, and hydraulically steep, The ground elevations range from
<br />approximately 5,500 feet in the northwestern portion of the city
<br />to 5,300 feet in the southeastern portion, Ground cover in the
<br />undeveloped portion of the basin is predominately buffalo grass,
<br />with willow and cottonwood trees, Niver Creek and Tributary L of
<br />Niver Creek share the above characteristics with the exception of
<br />the specific ground elevations,
<br />
<br />The major geologic units found adjacent to the flood plain areas
<br />in Federal Heights are post-piney alluvium and Piney Creek alluvium,
<br />The soils found in the flood plain areas are Arvada loam, ulm loam,
<br />sansil-shingle complex, and loamy alluvial,
<br />
<br />Federal Heights is located in a' semiarid high plain climatic region
<br />modified by the proximity of the Rocky Mountains. Because Colorado
<br />is situated in the central portion of a large landmass and is far
<br />removed from coastal moisture, the major influence on the climate
<br />is the State's continental location, In general, the climate is
<br />characterized by meager precipitation, a distinct summer season,
<br />and a marked winter season, when precipitation is mostly snow,
<br />
<br />The annual precipitation in Federal Heights is approximately 15
<br />inches, which includes an average snowfall of approximately 58
<br />inches, Average daily temperatures range from 300F in January to
<br />730F in July, with a daily temperature fluctuation of 25 to 30
<br />degrees,
<br />
<br />2,3 Principal Flood Problems
<br />
<br />Severe flood runoff is transported through Federal Heights as both
<br />overland shallow flow and as channel flow, The steep slope of the
<br />land, the close proximity of mopile homes to Tributary M of Niver
<br />Creek, and the presence of several culverts that are inadequate to
<br />convey major storm runoff combine to create flooding problems,
<br />
<br />The runoff upstream of Zuni Street is overland flow that can overtop
<br />roads and inundate mobile home trailers, The average slope is 3,5
<br />percent I therefore, excessive velocities occur,
<br />
<br />Downstream of Zuni Street, the runoff flows through culverts and
<br />well-defined channelsl however, there is some overland flow, Roads
<br />and trailer homes can be inundated, The average slope in this
<br />area is 1.5 percent,
<br />
<br />On June 13, 1984, severe rainfall runoff caused considerable damage
<br />to mobile home trailers, to private property, and to the channel,
<br />One fatality was directly attributable to the shallow overland
<br />flow, Unofficial estimates gave the peak dicharge from the storm
<br />as 800 to 1,000 cubic feet per second (cfs) at Pecos Streetl this
<br />was the result of a 4,2-inOO rainfall, which fell within 3 hours,
<br />
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