2025 Orange County Water Demand Projection Model
During the model fitting process, historical precipitation values were found to generate a better fit than departures from normal weather precipitation. Additionally, irrigation use is better defined by agency- declared stages than by State declarations. Irrigation is much more responsive to temperature and precipitation than the other sectors, as expected.
3.6.2
Historical Model Performance
Visual inspection and performance metrics showed good model performance, matching the seasonal cycles and quantities with high overall accuracy. Figure 3-5 shows the model performance for an example agency.
6000
5000
4000
3000
2000
1000
Observed
Modeled
0
Figure 3-5: Modeled vs Historical Water Use per Account for Irrigation for an Agency
3.7 Price Elasticity The sensitivity of the quantity of water demand to a change in its price is known as the price elasticity. The sector-specific results showed average price elasticities across the year, but the demand models allow the elasticity to vary by time of year. As water use becomes more discretionary in the summer, the estimated price elasticity (the response to price changes) tends to increase. Comparison of the four elasticity values in Figure 3-6 reveals that multifamily demand is the least price-responsive (i.e., the least elastic of the demand sectors). The other sectors show a blend in terms of when the price signal starts mattering more. For single-family use, price changes have a large impact in late spring and early summer. Prices for CII and irrigation have the biggest impact in the summer (irrigation price elasticity approaches a coefficient of -0.25, which means that a 1% increase in the volumetric price of water leads to a 0.25% decrease in water use per account). The average regional response to price varies for a given sector over the calendar year.
3-14
Appendix G - 51
Powered by FlippingBook