ClimateChange Assessment Guide.pdf - University of Waterloo

E-44Guide for Assessment of Hydrological Effects of Climate Change in Ontario Potential groundwater impacts from climate change are particularly significant within Subwatershed 19, as localmunicipalities obtain their drinking water from groundwater sources. Understanding the range of potential impactscan aid municipalities in their long-term water supply planning and in developing effective source water protectionstrategies.Monthly simulated groundwater recharge, estimated by the HSP-F model, for each climate change scenario was inputinto the MODFLOW model. The range in simulated groundwater recharge predicted by the nine GCM scenarios(2041-2070) is represented by the 5 th , 25 th , median, 75 th and 95 th percentiles of future monthly recharge rates includedin Figure 6-8. The monthly groundwater recharge for the baseline climate (1961-1990) is also included. Similar to themonthly streamflow, the median monthly recharge under climate change conditions is generally higher in the wintermonths, lower in spring and early summer, and similar for late summer and fall. Figure 6-8:HSP-F monthly recharge statistics with GCM climate change scenarios.Using the estimates of monthly groundwater recharge, the MODFLOW model was run transiently from 1961-1990 foreach climate change scenario, as well as the baseline climate scenario. Monthly estimates of groundwater dischargewere output, and are presented in Figure 6-9 as annual total groundwater discharge. The climate change projectionsshow a large range in annual groundwater discharge; however, five out of nine scenarios remain within 10% of thecurrent climate.