Laserfiche WebLink
<br />. <br />. <br />. <br />,. <br />,. <br />i. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />~-I <br />.""", PI, <br />. <br />. <br />. <br />.Co"'1/ <br />. <br />.OWl Z. <br /> <br />~M1. <br />.0 <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />i. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br /> <br />Vallecito Dam Operation <br /> <br />To model the Los Pmos River watershed below Vallecito Dam using HEC-l, the <br />Albuquerque District considered a release of 3,100 cfs from Vallecito Reservoir to represent the <br />maximum outlet release from the dam with the conservation pool full. This amount was agreed upon <br />by the Corps of Engineers, the USBR, the Colorado Water Conservation Board, and La Plata County. <br /> <br />Hydrologic Analysis Results <br /> <br />. <br /> <br />Table 3 lists the frequency discharge peaks generated for selected locations along the Los <br />Pinos River. Figures I through 4 show the four frequency hydro graphs of the Los Pmos River for <br />each of the locations listed in Table 3. <br /> <br /> TABLE 3 <br /> DISCHARGE FREQUENCY PEAKS <br /> 10.00/... 2.00/... 1.00/... 0.20/... <br /> Drainage Chance Chance Chance Chance <br />LOCA nON Area Flood Flood Flood Flood <br /> (sqmi) Discharge Discharge Discharge Discharge <br /> (cfs) (cfs) (cfs) (cfs) <br />~~!~~ ~;: a~~ Creek 14 3700 4500 5000 6700 <br />7g~ !~~s ~~~ ~~"" Colwnbus, CO 32 4600 6500 7800 11700 <br />7<?,slr~~s l},iver at ,B~"{ Creek 58 5400 8300 10200 16100 <br />ll.. ~, e-n"1.. <br />Los PUlos River at Bayfield, CO 70 5800 9200 11500 18600 <br /> <br />The HEC-I model, as developed by the Albuquerque District, includes several combination <br />points where tributary inflow hydro graphs are added to the Los Pmos River hydro graph. At the fust <br />combination point (COM-I), downstream from Vallecito Dam, three subbasin inflow hydro graphs <br />are combined, including Red Creek. Red Creek joins the Los Pmos River approximately 11,400 feet <br />downstream from the dam while COM-l is approximately 30,000 feet downstream from the dam. <br />Several bridges are located between these two locations, therefore it was necessary to add the Red <br />Creek flow upstream of these bridges. To facilitate the analysis, it was decided that a distribution <br />of flows based on drainage area ratios would be acceptable. The tributary area of the Red Creek <br />subbasin in the HEC-I model includes approximately 59% from Red Creek and 41% of tributary <br />area consisting of several minor arroyos that drain the adjacent hills. Consequently, 59% of the peak <br />flow was added to the Los Pinos at the Red Creek confluence and the remaining 41 % was added to <br />the Los Piiios at COM-I. <br /> <br />5 <br />