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historic records (such as mean and standard any monthly deficits)under stream flows reduced to <br /> deviation), and also provide a much greater at least 75% of average for a minimum of three <br /> combination of above and below-normal stream years. Using the CRDSS, it will soon be possible to <br /> flows. The synthetic record allows the water supply facilitate development of site-specific stream flow <br /> system to be tested against a wide range of sequences for west slope streams for design <br /> conditions that may not have been observed in the droughts expected to recur on a 25-, 50-, and 100- <br /> historic record but are nevertheless possible in the year cycle. This capability will be expanded to <br /> future. This provides a more reliable estimate of include other river basins as additional river <br /> system yields than can be obtained from evaluation decision support systems are developed. <br /> • of the historic data alone, and a more extensive <br /> ▪ number of drought events against which the design The CWCB is working with the Colorado Climate <br /> • drought can be compared and its severity more Center at CSU and Henz Meteorological Services to <br /> accurately determined. determine regional drought characteristics from <br /> existing climate records based on research for the <br /> In the design of the Colorado River Decision Climate Center's recent report on "Historical Dry <br /> Support System (CRDSS), one hundred data sets of and Wet Periods in Colorado." <br /> 100 years each characterizing drought for seven key <br /> stream gage locations on the west slope were <br /> developed. A preliminary analysis of the results Water management in the west is constantly <br /> show, for the west slope river basins, that the 100- evolving to sustain the needs of people living in <br /> year drought sequence has an average yield between an arid region. Colorado has adapted to this dry <br /> 71- and 83-percent of the long-term mean annual climate through experience, creativity, planning, <br /> flow and an average duration that lasts between 2.4 and diligence. Over the past decade, we have <br /> and 2.6 years. The average maximum 100-year enjoyed the benefit of being in a wet period. But <br /> drought sequence has an average yield between 68- the threat of severe, sustained drought looms over <br /> and 80-percent of the long-term mean annual flow Colorado and its vibrant economy. Growing <br /> and an average duration that lasts between 7.4 and population increases our vulnerability to the impacts <br /> 8.3 years. This task is still in progress, but the of drought. We may suddenly find ourselves back <br /> preliminary results based on synthetic stream flows in the days of fighting for our own survival and a <br /> provide a reasonable standard for local water subsistence economy if we take these water- <br /> providers to examine their water supply systems. plentiful years for granted. <br /> 100-year(P=0.01)Drought Characteristics <br /> 100% <br /> 00% <br /> 00% <br /> 'e <br /> 0D% •., <br /> i°c SO% <br /> a 2 •W1109fer Maim <br /> 40% <br /> •0mJiuI ar BILK U0h - - <br /> YahbaM<% - -_ <br /> Cn 30% ■IJtlYl/sle,artar - —' -- <br /> •coomb...em® <br /> 20% ■RmtueraWBre03o - a <br /> •Guntaustr 0MdJYL006 <br /> 10%. <br /> « 0% <br /> 0 1 2 3 4 _ <br /> 4•8•2017e0110tDtn 1 Ye,, <br /> Frederick Remington's 1903 painting "Fight for the Water <br /> Hole"reproduced with permission from the Houston Museum <br /> of Fine Arts. <br /> The CWCB recommends water providers, <br /> especially those that are experiencing strong <br /> population growth, start by determining how their <br /> systems would perform (calculate the magnitude of <br /> 7 <br />