Regionalization of Runoff Variability of Alberta, Canada, by Wavelet, Independent Component, Empirical Orthogonal Function, and Geographical Information System Analyses

Abstract

Statistical methods of wavelet, independent component analysis (ICA), and empirical orthogonal function (EOF) analysis were used together with geographical information systems (GIS) to regionalize runoff variability, establish baseline predisturbance hydrologic regimes, and account for runoff heterogeneity across Alberta, Canada as part of an effort to develop future adaptive forest management practices for Alberta. Both ICA and EOF identified three hydrologic clusters from 59 stations of catchment runoff data. However, ICA identified hydrologic clusters that agree better with the five ecoregions of Alberta than that of EOF. These are the Rocky Mountains and foothills, where runoff was characterized by a fairly consistent temporal variability and dominated by a strong annual cycle, southern Alberta/central Alberta, where temporal heterogeneity and a weak annual cycle dominated the runoff variability, and in southwestern Alberta, where the runoff variability was characterized by annual, 4–7, and 11-year cycles. Apparently stagnation moraine dominate hydrologic responses of most catchments in the grasslands and part of the boreal forests of western, central, and eastern Alberta. Empirical equations developed showed that stagnation moraine explained 64% of the runoff variability of selected catchments and that runoff was significantly diminished when stagnation moraines covered at least 74% of the catchment area. The identification of three spatially heterogeneous hydrologic clusters in Alberta, a province that is defined by four spatially homogeneous precipitation regimes indicates the necessity to develop forest management practices that will be suitable to manage Alberta’s forests.