2025 Orange County Water Demand Projection Model
Consecutive dry-year scaling factors are derived using the historical minimums of the precipitation and historical maximum of the temperature variable from the historical weather data set.
Equation 6-4 shows the 2 nd consecutive dry year scaling factor.
𝐹𝑎𝑐𝑡𝑜𝑟 = 𝑀𝐴𝑋𝑇12 .ଶଽ × 𝑃𝑅𝐶𝑃24ି .଼ ଷଶ =1.1195
Equation 6-4
Equation 6-5 shows the 3 rd consecutive dry year scaling factor.
𝐹𝑎𝑐𝑡𝑜𝑟 = 𝑀𝐴𝑋𝑇12 .ଶଽ × 𝑃𝑅𝐶𝑃24ି .଼ ଷଶ × 𝑃𝑅𝐶𝑃36ି . =1.1265
Equation 6-5
Equation 6-6 shows the 4 th consecutive dry year scaling factor.
𝐹𝑎𝑐𝑡𝑜𝑟 = 𝑀𝐴𝑋𝑇12 .ଶଽ × 𝑃𝑅𝐶𝑃24ି .଼ ଷଶ × 𝑃𝑅𝐶𝑃36ି . × 𝑃𝑅𝐶𝑃48ି .ଶଽ =1.1478 Equation 6-6
Equation 6-7 shows the 5 th consecutive dry year scaling factor.
𝐹𝑎𝑐𝑡𝑜𝑟 = 𝑀𝐴𝑋𝑇12 .ଶଽ × 𝑃𝑅𝐶𝑃24ି .଼ ଷଶ × 𝑃𝑅𝐶𝑃36ି . × 𝑃𝑅𝐶𝑃48ି .ଶଽ × 𝑃𝑅𝐶𝑃60ି .ଶଽ = 1.1673 Equation 6-7 These scaling factors are used to supplement the results of the single hot/dry year scenario. There is a 5- year sequence for any year in the forecast: single hot/dry year, followed by the second dry year, followed by the third consecutive dry year, and so on. Under these assumptions, the second consecutive dry year would result in water use that is about 12 percent higher than under normal precipitation conditions. The estimate of water use for the third consecutive dry year would be incrementally higher, or about 13 percent greater than normal. By the end of the fifth consecutive dry year, the estimated potential would grow to about 17 percent higher than the normal year baseline. The consecutive dry year scenarios are calculated based on the total baseline forecast and thus implicitly account for differences in growth occurring among Orange County’s water use sectors and agencies. As indicated by the magnitudes of the scaling factors described above, this implies increasingly higher demands as conditions become drier. It is possible that demands would be restricted through demand management actions prior to reaching these levels if such conditions were to occur.
6.1.3
All UWMP Scenarios
All UWMP scenarios are shown in Figure 6-1 , along with the baseline, high demand, and low demand scenarios discussed in the previous sections.
6-4
Appendix G - 73
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