An extreme analysis for the 2010 precipitation event at the South of Saskatchewan Prairie

After a prolonged drought period in the early 2000s, the Canadian prairie experienced a remarkably
wet year in 2010. Five stations near the edge of the Saskatchewan boreal forest recorded historically
high cumulative precipitation (from April to September). The exceptional wet year causes the public
concerns on flood controls and land use management in the region. Using the Canadian National
Climate Data Achieve, characteristics of six-month cumulative precipitation sums over
Saskatchewan prairie are investigated by the Generalised Extreme Value (GEV) Theory. Based on
the unconstrained GEV distribution, the 2010 event is outside the estimated 95% confidence
intervals for the five Canadian prairie stations. On the contrary, the exceptional high 2010 cumulative
perception sums for the five stations are still bounded by the estimated confidence bounds if the
GEV distribution is constrained to the Gumbel distribution (i.e. setting the shape factor of the GEV
distribution to be zero). These results demonstrate that the classical extreme analysis is useful for
planning unprecedented extreme events in the Canadian Prairie, if the GEV distribution is
constrained to the Gumbel distribution with the estimated uncertainty bounds based on the order
statistics.