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<br />/'\,...., ') 0 ."1l <br />'..J... ..:)....,.:i: <br /> <br />TEMPERATURE 0 c <br />0510152025&l <br />1.00000 <br /> <br />.999 <br /> <br />>- <br />I- <br />in <br />z <br />w <br />o <br /> <br />.998 <br /> <br /> <br />Figure 2. VarlatlOD or water deDslty. <br /> <br />.997 <br /> <br />.996 <br /> <br />.995 <br /> <br />the center of gravity when the water is in any given <br />state of stratification and the center of gravity when <br />the water is isothermal (which is the minimum <br />energy required to completely mix the stratified <br />water). The actual energy required to accomplish <br />such mixing has been found to be on the order of <br />100 limes this theoretical minimum (Symons. <br />1969). <br /> <br />Typical temperature profiles for Lake Powell <br />at various seasons are shown in Figure 3. The <br />temperature profile is almost vertical (isothermal) <br />in February. but the strength of the thermocline <br />increases until in August, there is a difference of <br />200C between the surface and the bottom. During <br />the fall months the thermocline decreases due to <br />the loss of stored energy when the air is colder than <br />the water. <br /> <br />The thermocline on smaller Utah reservoirs is <br />not this pronounced but is stiH very significant on <br />most impoundments over SO feet in depth. <br />Porcupine Reservoir. for example, with a depth of <br />140 feet had a thermocline of I30C during July of <br />1974. <br /> <br />00 <br /> <br />TEMPERATURE (0 C ) <br />5 10 15 <br /> <br />30 <br /> <br /> <br /> 100 <br /> FEB.8,1972 <br /> 200 I MAY 3, 1972 <br /> :~ AUG. 9,1972 <br />:I: I NOV. 14,1972 <br />l- I <br />lL 300 I <br />I <br />l<J I <br />0 I <br /> I <br /> I <br /> 400 I <br /> I <br /> <br />500 <br /> <br />/MAX DEPTH = 561' I <br />DRAWDOWN AVG. = 80 ! <br /> <br />600 <br /> <br />Figure 3. Lake PoweU temperatDre prom... <br /> <br />3 <br />