Using hydroclimatic extremes to guide future hydrologic predictions
Abstract. There are growing numbers of studies on climate change impacts on forest hydrology but limited attempts have been made to use current hydroclimatic extremes to constrain future climatic conditions. Here we used historical wet and dry years as a proxy for expected future extremes in a boreal headwater catchment. Hydrologic model ling assessments showed that runoff could be underestimated by at least 35 % when dry year parameterization was used for wet year conditions. Uncertainty analysis showed that behavioural parameter sets from wet and dry year separated mainly on precipitation related parameters and to a lesser extent on parameter sets related to landscape processes. While inherent uncertainty in climate models still drives the overall uncertainty in runoff projections, hydrologic model calibration for climate impact studies should be based on years that best approximate future conditions to constrain uncertainty in projecting future conditions.