Laserfiche WebLink
<br />OJ1824 <br /> <br />Lakes Mohave and Havasu Reach <br /> <br />The upstream and downstream stations for this reach are the Colo- <br />rado River below Hoover and Parker Dams, respectively. Because <br />there are no available data below Davis Dam, the reservoir effects <br />of both Lake Mohave and Havasu had to be combined. <br /> <br />Initial modeling attempts took into account volumetric changes of <br />the reservoirs and bank storage, but did not, treat evaporation <br />explicitly. As a consequence, evaporation was included in the <br />computed ungaged inputs. Model runs treated this stretch as a <br />river reach, assuming that the reservoirs were at a constant level. <br />This approach was unsuccessful, primarily because there was no <br />"dampening" or "forgiving" effect of the reservoir to fluctuations <br />and errors in the ungaged inputs. The failure to simulate reSer- <br />voir operations was believed to be of minor importance. Introduc- <br />tion of the reservoirs effectively reduced the downstream variance <br />in quality to more realistic levels. <br /> <br />Because of limitations in the utility programs used with the model, <br />the estimated historical evaporation from each reservoir was first <br />computed using the area-capacity relationships of Table I in con- <br />junction with the mean Lake Mead evaporation rates of Table II and <br />the historic end-of-month contents, Tables C-17 and C-18, and <br />Figures C-18 and C-19. The estimated evaporation amounts are <br />shown in Figures C-20 and C-21, and in Tables C-19 and C-20. <br /> <br />Inspection of Figure C-19 reveals a distinct change in the pattern <br />of reservoir volumes for Lake Bavasu, commencing in 1957. Although <br />this could be attributed to an altered operating policy after Lake <br />Mead reached low levels in 1956, it is apparently due to silting. <br />The reservoir was resurveyed in April, 1957, and the area-capacity <br />relations updated. Data were not adjusted to reflect this effect. <br />The resultant error is tolerated and considered acceptable. <br /> <br />It is noted that Davis Dam began storing water to create Lake <br />Hohave in 1950, and that the gross storage is three times greater <br />than that of Lake Havasu. The combined volumes, used in computing <br />the ungaged inputs, are shown in Figure C-22. <br /> <br />The Metropolitan Water District pumps water directly from Lake <br />Havasu and was considered in computing the ungaged flows. His- <br />toric pumping is indicated by Figure C-23 and Table C-21. Since <br />present modified data are used for the mainstem streams, ~'/D <br />should also be represented at present levels. For flow, this is <br />the 1970 historic values. The corresponding salinity loads were <br /> <br />14 <br />