Laserfiche WebLink
Water & Sewer Authority of Cabarrus County <br />Water and Wastewater System Master Plan <br /> <br />Safe Yield Update and Regional Drought Operations <br /> <br /> Table 7 <br /> Lake Howell, Seasonal Drought Operating Curve Data <br /> Crest Eievation= 650 feet with a usable volume of 5.3 billion gallons Simulated Data <br /> <br /> Stage 2 ] Stage 3 [ Siage 4 Stage 2 [ §'t~ge 3 Stage 4 Stage 2 Stage 3 Stage 4 Stage Volume % Vol <br /> <br />May 70.0% 60.0% 50.0% 3707 3178 2648 645.5 643.9 642.2 647.7 4458 84 2% <br />Jun 70.0% 60.0% 50.0% 3707 3178 2648 645.5 643.9 642.2 647.5 4372 82.6% <br />Jul 70.0% 55 0% 45.0% 3707 2913 2383 645 5 643.1 641.3 647.0 4212 79.5% <br />Aug 70 0% 50.0% 40.0% 3707 2648 2119 645.5 642.2 640.4 646.7 4118 77.8% <br />Sep 70 0% 45.0% 35.0% 3707 2383 1854 645.5 641.3 639.5 646.3 3983 75.2% <br />Oct 70.0% 40.0% 30.0% 3707 2119 1589 645.5 640.4 638.4 645.9 3844 72.6% <br />Nov 70.0% 40 0% 30.0% 3707 2119 1589 645.5 640.4 638 4 645.7 3782 71 4% <br />Dec 70.0% 40.0% 30.0% 3707 2119 1589 645.5 640 4 638.4 646.3 3972 75.0% <br />Jan 70.0% 45.0% 35.0% 3707 2383 1854 645.5 641,3 639.5 646.7 4125 77.9% <br />Feb 70.0% 50 0% 40.0% 3707 2648 2119 645 5 642.2 640.4 647.4 4347 82 I% <br />Mar 70 0% 55 0% 45 0% 3707 2913 2383 645.5 643.1 641.3 647.9 4532 85.69o <br />Apr 70 0% 60 0% 50 0% 3707 3178 2648 645.5 643.9 642.2 648.0 4553 86 0% <br />May 70.0% 60 0% 50.0% 3707 3178 2648 645.5 643 9 642.2 647.7 4458 84 2% <br /> <br />2.4.4 Frequency Analysis. <br />As mentioned previously, an effective drought monitoring program must not trigger the <br />need for water restrictions so prematurely or frequently that the overall drought <br />contingency plan becomes ineffective. With this in mind, this evaluation examined the <br />frequency of drought stage triggering over the entire simulated record. Conservation <br />measures resulting in reduced demand, and reduced downstream releases are simulated, <br />corresponding to drought stage. The resulting simulation of Lake Howell pool elevation <br />is shown on Figure 16. Under these conditions, a Stage 2 drought condition would be <br />called in 3 droughts over the 103 year record, or a frequency of once ?ery 33 years <br />(Table 8). Stage 3 and 4 restrictions would be implemented in only one drought over the <br />103-year record. That drought event is the 1998-2002 occurrence. <br /> <br />Normal <br /> <br />Table 8 <br /> <br />Frequency of Entering Droug[ <br /> Sta_.g~.l Stye2 <br /> <br />Stage By Events (103-yr) <br /> Stage 3 I Stage 4 <br /> 0 I 1 <br /> <br />Another consideration is the cumulative amount of time that the water customers would <br />experience the various stages of drought restrictions. These are expressed in two <br />different ways in Table 9. First, the percentage of months of the entire period (103 years) <br />of simulation is shown. Then the number of months that each Stage would be expected <br /> <br />PN 096873.0800 2 1 ~'~, <br />January 23, 2004 BLACK & VEATCH <br /> ~l~w ~ International Company <br /> <br /> <br />