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<br />. <br /> <br />. <br /> <br />. <br /> <br />., ') <br />ft. r. ",'') , '. <br />U'U0a~'" <br /> <br />PART IX. VIRGIN STREAMFLOW ESTIMATE AT CONFLUENCE OF <br />WEST, MIDDLE, AND EAST MANCOS RIVERS 1952-1980 <br /> <br />Basin Characteristics <br /> <br /> <br />The virgin flow for the upper Mancos River at the gaging stations for <br /> <br />1952 through 1980 was estimated through use of the La Plata River at Hesperus <br /> <br /> <br />virgin flow figures. The upper Mancos and La Plata drainage areas are adjacent <br /> <br />and have similar hydrological characteristics. <br /> <br />West, Middle & East <br />Mancos River <br /> <br />La Plata River <br />at Hesperus <br /> <br />Drainage basin (sq-mi) <br /> <br />66 <br /> <br />37 <br /> <br />Mean basin elevation (ft) <br /> <br />10,500 <br /> <br />9,500 <br /> <br />Average annual virgin flow <br />1938-1951 (ac-ft) <br /> <br />47,000 <br /> <br />35,600 <br /> <br />Average annual virgin flow <br />per square-mile (ac-ft) <br /> <br />710 <br /> <br />960 <br /> <br />Annual con-elation coefficient <br />Mancos vs. La Plata <br /> <br />.97 <br /> <br />Standard deviation en-or for <br />Mancos flow (ac-ft) <br /> <br />5,000 <br /> <br />ReRression Analysis <br /> <br /> <br />The monthly flow patterns for the Mancos and La Plata rivers were found <br /> <br /> <br />to be almost identical. A comparison of the monthly flows for the two rivers <br /> <br /> <br />is presented in Table 9. The 1938 through 1951 period of record includes one <br /> <br /> <br />year of very high streamflow (1941) in which the recorded flow for the La Plata <br /> <br /> <br />River was considerably greater than at any other time during the 50 years the <br /> <br /> <br />gage has been in operation. The recorded La Plata River flow in 1941 was 76,090 <br /> <br /> <br />acre-feet, but the highest annual flow during 1951 through 1980 was 55,660 <br /> <br /> <br />acre-feet. Heavy rains during September and October 1941 resulted in extremely <br /> <br /> <br />high flows on the Mancos and La Plata rivers during the autumn months, a condi- <br /> <br />-26- <br /> <br />" <br />