FLOOD07461 - Laserfiche WebLink

Home Browse Search

-},:.'. Hydrology for Yuma County, Colorado, and Wray, Colorado Flood Plain Information Reports 1. Purpose. This report presents hydrologic data for use in the Yuma County, Colorado, Flood Plain Information Report and the Wray, Colorado, Flood Plain Information Report. Peak flows and hydrographs have been developed for the 10, 100, and 500 year flows just downstream of Wray and at the Colorado-Nebraska State line. 2. Basin Description. Yuma County is located in the northeast portion of Colorado approximately 135 air miles east-northeast of Denver. The city of Wray is located within Yuma County in the North Fork Republican River Basin. The North Fork Republican River is the principal stream in the county and Chief Creek is its major contributing tributary stream. A map of the stream and its contributing drainage area is shown on Chart 1. Elevations in the North Fork Republican River basin range from about 3,338 feet above N.G.V.D. at the Colorado-Nebraska State line to about 3,860 feet above N.G.V.D. at the upper boundary of the contributing drainage area. The elevation at Wray is approximately 3,520 feet above N.G.V.D. The basin is comprised largely of sandhills having an ill defined drainage pattern and a wide range of terrain slopes. The basin is somewhat irregular in shape with the major axis oriented in a southwest- northeast-easterly direction. Although the total drainage area at U.S. Highway 385 on the west edge of Wray is 1,216 square miles, only 50 square miles actually contribute to surface runofr'- The ultimate drainage .area at the Colorado-Nebraska State line is lc~QO square miles with~_square miles actually contributing to runoff. A tributary stream, Chief Creek, joins the North Fork Republican River about one mile upstream of Wray. A small lake, Stalker Lake, is located about two miles above Wray on Chief Creek and is maintained as a fish preserve by the Colorado Fish and Game Commission. The lake has little influence in the control of floodflows due to its unregulated spillway. The watershed is predominately crop and pasture land with less than two square miles urbanized. Few artificial ponds have been built in this basin since most of the water for irrigation is obtained by either pumping from wells or by taking water from several irrigation canals which run parallel to the river at different locations throughout the river's length. 3. Climatology. The climate of the area is generally semiarid. The Gulf of Mexico is the primary source of moisture. This region of Colorado normally has hot surmners and long cold winters. Sunnner precipitation in the form of localized, highly intense, short duration thunderstorms accounts for much of the total annual precipitation. Normal annual precipitation over the study basin averages 18.5 inches per year.