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Date of Award

Fall 2012

Degree Type

Thesis

Degree Name

Master of Applied Science (MASc)

Department

Civil Engineering

Supervisor

Paulin Coulibaly

Language

English

Abstract

The thesis aims to investigate the impact of climate change on the hydrology of four semi-urban watersheds in southern Ontario. The study is mainly concerned with future changes in climate variables and flow regimes. The study also assesses future changes in the frequency and magnitude of peak and low flows. The hydrologic effects of climate change were assessed using a couple of climate and hydrological models. Three regional climate models (RCMs), namely, Canadian Regional Climate Model (CRCM), United States Regional Climate Model 3 (RCM3), United Kingdom Hadley Regional Model 3 (HRM3) were used to extract raw climate variables. The raw RCM data were corrected using a bias correction method. The method performance statistics and the nonparametric test results revealed that the bias corrected climate variables followed the patterns of the observed climate variables for all weather stations. Future climate scenario was then simulated and analyses show increases in annual precipitation about 5-8% and increases in mean annual daily mean temperature about 2.6-3.2 oC. Three hydrological models (namely HBV, MAC-HBV, and SAC-SMA) were used for flow simulation. The models' validation results show a good agreement with the observed flow with a Nash Sutcliffe efficiency around 0.49-0.75 and a correlation coefficient of around 0.7-0.8 for all sub-basins. The three hydrologic models coupled with the bias corrected RCMs data were used to simulate current and future flow. For future period (2050s), the models predicted increasing winter flow and decreasing spring, summer and autumn flows. Mean annual flow shows slight to moderate changes. Significant increases in peak and low flow magnitude are predicted for higher return periods (20-100 years). Overall, the effects of projected future changes in precipitation and temperature clearly govern the significant changes in seasonal and annual flows, peak and low flow magnitudes and frequencies. Using three hydrologic and three climate models projections, a comprehensive picture of probable hydrologic impact of climate change was assessed in the study area. The wide range of predicted changes will have significant implications for future water resources development in the selected semi-urban watersheds.

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