ClimateChange Assessment Guide.pdf - University of Waterloo

E-42Guide for Assessment of Hydrological Effects of Climate Change in OntarioHigh flow statistics are important for reservoir storage and dam operation, as well as channel design. High flows canbe represented by the maximum daily flow experienced each year, and are shown in Figure 6-5. Overall, there is atrend of increasing high flows, which is to be expected with the majority of future climates having higher precipitationamounts. A single year (1974) shows a significant decrease. Reductions in high flows would be associated with areduced snowmelt occurring in spring, due to more frequent snowmelt events occurring throughout the warmer winter.Several years show no appreciable difference in high flows between the baseline climate and the nine future climates. Figure 6-5:HSP-F maximum daily streamflow with GCM climate change scenarios.The climate change assessment for Subwatershed 19 also considers additional future climates, generated by thedownscaling methods as outlined in Section 5. Mean annual streamflow under the baseline climate (1961-1990) andthe SDSM downscaled scenarios are shown on Figure 6-6. The GCM scenarios associated with SDSM climates arealso shown for comparison. SDSM climates do not match the sequence of events of the current climate, as changefield climates do. Therefore while the two GCM change field climates in this figure closely follow the pattern of thecurrent climate, the SDSM climates do not. For this reason these climates should be compared in terms of thechanges in extremes rather than changes in any particular year. In this regard, the SDSM climates produced thelowest low flows and the highest annual average in any year (i.e., 1980).