Trends in snowcourse and streamflow data in British Columbia and the Yukon

In this study, records for nine snowcourse and eighteen streamflow stations in British Columbia and the Yukon are analyzed for trends which may be associated with climate change. The longest record is 72 years and the shortest is 26 years.Streamflow and snowcourse data have properties such as non-normal distribution, missing record and external interventions which impede statistical analysis. In particular, interventions (changes) may significantly affect the stochastic manner in which a series behaves. Such changes generate trends. For these reasons the analysis of such data is conducted using various smoothing techniques and test statistics, generally termed exploratory data analysis.From a visual examination of the output of the smoothing techniques, it appears that there is a tendency over the last thirty years for a decrease in snow water equivalent and streamflow in the southern portion of British Columbia and an increase in the north. But a more rigorous statistical analysis shows only a small percentage of the records have statistically significant trends.