Flood producing mechanisms identification in southern British Columbia, Canada

The causes of peak flows in two climatically different mountainous-forested basins of British Columbia have been identified. The U.B.C. watershed mode l was used to identify the causes of peak flows, since this model separatel y calculates the runoff components, i.e. rainfall, snowmelt and glacier run off The results showed that the flood flows in the maritime basin of Upper Campbell are mainly generated by rainfall during the fall months and winter rain-on-snow events. Rainfall runoff constitutes the largest percentage of peak flow for all types of events. On the other hand, the flood flows in t he inland basin of Illecillewaet are mainly produced by spring rain and sno wmelt events, snowmelt events alone and summer events when runoff from the glacier melt contributes to peak discharge. However, snowmelt runoff is the dominant component of peak hows. Based on these findings, flood frequency analysis showed that considering the flow component frequency distributions marginally improves the probability distribution flows in the two examined watersheds. (C) 2000 Elsevier Science B.V. All rights reserved.