WSPC05293 - Laserfiche WebLink

Home Browse Search

,KUI.1 U~t:.r'H Kt:.l.JIUN 0 Ut:.H r.t:Jt:J:)/t:Jt:Jo ~~L-~~~~~~~ ~~.~~_ .' . . . IU '::;I-bbbqq(,,+ L.:... o:J,,). . ':'-;0.. 1 B: 5'? 000219 Etl'~ti on Snowt'aIl and Snowmelt · Temperature Increases wlll shirt the tlmJng of runoff, causin~ B diit!nct Increase in winter runoff and a decrease In spring runoff. Higher elevatlOns that receIve IArg~ amounts of snow will by most affected by predIcted ir:crea.s~s In temperature. Under scenarios of clImate chango, these regions will not only receive less snow, but thai snow will produce leu runoff because evaporation wJlllncrease. I I Temperature Increases wllI also cause a decre~ in winter snowfall and snowpack, an increase In winter rain. and a faster and earlier spring snO\lffilelt. Such a shift in timing of runoff would have dramatic adverse effects on the recreatIonal sklindustry and on the natural erosystems of the region. i I These temperature.driven changes could Increase the potential for winter and sprllli flooding In some part! of tho region, I I Tne results suggest that Increases in temperature of as little as 20C \Iiould shift peak runoff In the Upper Colorado River Basin to the mOnth of May rather than June.' I . i Effecls on Salinity and Waler Quallty I · A 20 percent reduction in current annual river flow would cause all iccrease in sallnit)' In the Colorado River of 15 10 20 percent, I I High salinity levels, already a crltical concern for the lower Cclorado basin (afTectlll8: California, ArIzona, Nevada, and Mcxko)J would be greatly worsened by anYi decre!l~es In runoff, Even if runoff increem hy 20 percent, sallnlt)' limits will be~ exceeded continuously for long period.. . I Eff~ts 01\ Reseli'olr Levels and Hydroelectrlclly Generation . i · Hydroelectricity production and reservoir storage are extremely sensitive to changes,' in runoFF, In the Upper Colorado Basin. a reduction in flow of 10 percent causes average annual storage to decrease by 30 percent and power production to drop by 26 percent. If flows were to drop by 20 porcellt, power production In the Upper Colorado Basin decreases by 49 percent and storage in the reservoirs drops 63 percent. Such impacts would greatly affect tourism and water recreation, and other i sources of electricity would have to roplace the lost hydropower. I ln the Lower Colorado Basin, a 20 percent reduction In average annual flow would I cause mean annual reductiOn! in water stored in the reservoirs of as much as 70 I percent and reductions In hydroelectric power generatfon of 60 perceot. . . . . A decrease in runoff of 20 percent would leave Lake Mead essentially empty 25 percent oE the time, and the minimum water level needed for power generatton would never be reached, , I If average runoff increases by 5 percent, overall power generation jumps by 1 : thousand glgawlltt-hours (GWh) per yetlf. or 11 percent, while stornse increases by I 14 percent. rn the + 10 percent runoff scenario, POwer generation increases by 21 : percent and storage volumes in reservoirs ~o up 28 percent.