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Sharif, Hamed

University of British Columbia

Identifying the level of simplicity/complexity of catchment functional behavior, among large sample of catchments, and exploring the mechanistic causes and drivers of such behavior, could inform developing a generalizable theory of catchment functional dynamic of stormflow generation. This thesis proposes a top-down data-driven framework that informs the level of functional simplicity/complexity of catchment’s stormflow generation, using available observations of streamflow and precipitation across hundreds of rain-dominated catchments spanned globally. The degree to which the relation between event-scale water input and stormflow volume in a given catchment can be explained by a simple linear relationship is being used to classify catchments into three behavioral classes, namely, simple, intermediate and complex catchments. I then developed a conceptual hydrological model for each study catchment to simulate the time-series of shallow and deep flowpaths. The simulated flowpaths are coupled with spectral analysis to explore the mechanistic causes of the celerity response characteristics of simple catchments. The climatic and topographic drivers of functional simplicity/complexity are explored. The results suggest the prevalence of simple functional dynamic of stormflow generation among the study catchments, particularly during dormant season, with a strong (mostly one-line) linear relationship (R²≥0.75) between water input and stormflow volume. Such functional simplicity is associated with a strong coherency between water input and shallow flowpath time-series, suggesting that the water input driven perturbations during stormflow events are being translated through shallow flowpath to streamflow using a time-invariant transfer function. Indeed, regardless of the time of occurrence of the stormflow event and water input characteristics (e.g., intensity, duration, volume), a typical simple catchment embraces a unique, linear and time-invariant functional dynamic, during dormant and/or growing seasons. With some exceptions, simple functional dynamic occurs in landscapes with wet and out-of-phase climate and steep topography. Quantitative and conceptual understanding of the constitutive relationships among event-scale water input volume, stormflow volume, storage deficit volume, and the rate of event-driven perturbation decay (and propagation) are provided. The results can be considered as the fundamental first step in understanding the mechanistic causes and drivers of functional complexity, informing the development of a generalizable theory on catchment functional dynamic of stormflow generation.

Text

2025-02-28

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/87423

Geological Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/