CLIMATE CHANGE IMPACTS AND FLOOD RISK ANALYSIS IN MACKENZIE RIVER BASIN: A MODELING BASED COMPARATIVE STUDY CONSIDERING AND NOT CONSIDERING TRENDS IN HYDROLOGIC VARIABLE

摘要

An attempt has been taken here primarily to evaluate climate change impacts in a substantial as well as the principal portion (Liard River basin) within the Mackenzie River basin of North-West Canada and then to accomplish flood risk analysis for the same area. After selecting the representative stations for the basin and collecting data for 'extreme annual flow', trend analysis is accomplished to determine climate change effect on this hydrologic variable. The results showed that most of the stations didn't have any statistically significant trend, while only one station showed to have significant increasing trend and two stations showed significant decreasing trends in flow data with time. These outcomes tend to indicate that climate change might not have that much significant effect on 'extreme annual flow' in the basin. Then, Monte Carlo simulation is applied to perform risk analyses for the individual stations and for a set of combined data mainly for two options: without considering any trend in flow data, and considering significant trends in flow data. Risk has been evaluated for the 50 years return period flood and interpreted by a term 'Threshold Flood Flow' defined as the minimum 'extreme annual flow' required to cause flood in a particular year. Results from the individual stations proclaim that flood risk seems to be less in magnitude with decreasing trend and high in magnitude with increasing trend in data, both compared to the risk estimated in no trend case. Results from the combined data set seem to proclaim that flood risk is actually slightly decreasing in Mackenzie River basin day by day.