Assessing the Potential Impact of Climate Change on Surface Hydrology of Prince Edward Island

Abstract

This study used the HBV hydrological model to assess the potential impact of climate change on five watersheds on Prince Edward Island, Canada. The model was successfully constructed and calibrated using a 2000 run Monte Carlo simulation. One parameter set was found to produce satisfactory simulations for three of the six catchments, suggesting that the physical characteristics of the watersheds are similar. Six climate scenarios comprising three emission scenarios and four global coupled models were used as model input to assess potential climate change impacts on the hydrological system for the period 1985 - 2044. Overall, most components of the hydrological system showed little to moderate change. Mean annual drainage increases by 8% in the most likely scenario, but increases up to 23% in wetter scenarios. Seasonally, the increased flow is shown to occur in the winter (+38%), while spring melt flows drop by 12% and summer flows show little change (+7%). Fall flows increase in wetter scenarios (up to +33%) but drop in drier ones (‑12%). Annual flow indicators (Q10, Q50, Q90) remain stable in the base-case scenario, but show small, steady increases in all other scenarios. Assessment of summer drought severity shows that there is little change to both the 7Q10 and 60Q50 droughts. Analysis of the annual water balance components showed some larger changes. While the runoff coefficient is steady around 0.6 and evapotranspiration shows a minor increase in all scenarios, net recharge to deep groundwater decreases by at least 15% and up to 60% in the base-case scenario. Winter snowpack volumes also decrease between -40% and -71% in the last decade of simulation in all scenarios. Overall, change values between historic and future periods from the six simulations agree in direction for nearly all results, and show only moderate variation (generally less than 30 percentage points) in magnitude. This indicates that the impact of climate change on the hydrological system in Prince Edward Island is relatively well constrained.