Sensitivity of Hydrologic Systems to Climate Change

If climate change occurs, it could seriously impact water resources in Canada. In this paper I examine the change in flood probabilities in a study watershed in central Alberta in response to increases resulting from global warming in the mean and standard deviations of rainfall depths of storms of various durations. A 25% increase in the mean and a 50% increase in the standard deviation of storm rainfalls were selected based on the assumption that climates typical of southern Alberta, Montana and Colorado would extend northward to central Alberta. Lumped and semi-distributed modelling of the study watershed was used in a Monte Carlo simulation of floods resulting from the new climatic scenario. Simulation results show that modest increases in storm rainfall could result in large changes in flood magnitudes. Consequences of such flow increases on the capacity of a small dam spillway are illustrated.