Draft 2025 Urban Water Management Plan

2025 Orange County Water Demand Projection Model

Future climate projections based on many CMIP6 models indicate a general increase in water demands over the forecast period ( Figure 5-3 ). Note that the models shown are applied to a total baseline demand scenario prior to member agency review and final numbers were published.

520,000

510,000

Dry Warm

500,000

490,000

480,000

Wet Cool

470,000

460,000

450,000

Baseline

DryWarm: CNRM-ESM2 - 1_585

DryWarm: MIROC6_585

DryWarm: KACE-1-0-G_370

DryCool: MRI-ESM2-0_370

DryCool: CESM2-LENS_370

DryCool: MPI-ESM1-2-HR_370

DryCool: GFDL-ESM4_370

WetWarm: HadGEM3-GC31-LL_585

WetWarm: ACCESS-CM2_585

WetWarm: ACCESS-CM2_370

WetWarm: TaiESM1_370

WetCool: EC-Earth3-Veg_370

WetCool: FGOALS-g3_370

DryWarm: KACE-1-0-G_585

WetCool: FGOALS-g3_585

Figure 5-3: CMIP6 Climate Change Futures

CMIP6 data from the 15 model runs that were determined to be a good fit for California were substituted for baseline weather conditions in the demand model, and the resulting total Orange County demand was used to define a dry warm (high demand) scenario and a wet cool (lower demand) scenario to provide a range of possible climate impacted outcomes. Both scenarios predict increasing temperatures, and as a result, water demands that are higher than baseline demands.

5-4

Appendix G - 67

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