ClimateChange Assessment Guide.pdf - University of Waterloo

Appendix E E-51Subwatershed 19 Case StudySubwatershed 19 is a‘Moderate’ StressSubwatershed .Figure 7-1: Tier Two groundwater Stress Assessment (CVC, 2009).The Tier Two Subwatershed Stress Assessment conducted in this study identified Subwatersheds 10, 11, and 19 ashaving the potential for moderate or significant hydrologic stress under current and future water demand conditions.Within these subwatersheds, Acton and Georgetown, within the Regional Municipality of Halton, and the Town ofOrangeville are required to complete a Tier Three Water Quantity Risk Assessment to meet their requirements underthe Clean Water Act. The objective of this case study is to demonstrate how the results of the subwatershed stress assessment might beaffected after considering the potential impacts of climate change. The climate change impact assessment considersa total of 12 climate scenarios (11 future climates plus the current climate) as described earlier in this case study,each of which estimates an average annual groundwater recharge rate as needed to complete percent water demandfor each subwatershed. The surface water flow model was run to estimate groundwater recharge for each of the 12scenarios. Table 7-3 lists each of the climate scenarios considered, with groundwater supply recalculated for each ofthe scenarios. Groundwater reserve and consumptive demand were assumed to be constant, at current levels inorder to calculate a new percent water demand for each of the 12 climate scenarios.