Upscaling in Computational Hydrology: Chasing after the “Holy Grail”

Dr. James Craig
Friday, April 26, 2019 · 1:00 pm
ESB 5104
Presenter: Dr. James Craig, CRC in Hydrologic Modelling and Analysis
Date: Friday, April 26
Time: 1pm
Location: ESB 5104
Biography of the presenter:
Dr. James Craig, Ph.D., P.Eng., is a Canada Research Chair in Hydrologic Modelling and Analysis and an Associate Professor in Civil and Environmental Engineering at the University of Waterloo. Dr. Craig is an expert in hydrological model development, lead author of the Raven hydrological modelling framework, and an award-winning University instructor.  Dr. Craig’s expertise is in numerical and analytical modelling of environmental systems, with a focus on surface water hydrology, regional scale groundwater flow, and subsurface heat and pollutant transport simulation. 
Title of talk: Upscaling in Computational Hydrology: Chasing after the “Holy Grail”
Scale issues are ever-present in the modelling of hydrologic processes. While hydrologists have a fairly refined understanding of the drivers of changing soil moisture, snow melt, and evaporative demand at the scale of a single soil plot, snow pillow, or plant, determining how these ‘point-scale processes’ integrate over a hillside, farm, or watershed is elusive. Explicitly modelling all of the detail is nigh impossible. This is due the naturally occurring heterogeneity in any environment, the difficulty of practically characterizing heterogeneous internal properties and states, and our inability to measure integrated fluxes anywhere but at stream gauges. Computational hydrologists have developed a number of approaches for addressing this combined lack of system knowledge at scales of interest via ‘upscaling’ approaches which attempt to represent the net behavior of a system driven by point-scale physics over a heterogeneous domain, in effect replacing the complications of a heterogeneous world with new physical relations which describe the dependence of bulk fluxes upon bulk storage and (often) statistical descriptions of internal heterogeneity.
This talk provides an overview of intentional and inadvertent upscaling approaches in hydrology, describes the challenges in chasing after this ‘Holy Grail’ of hydrology, and discusses a few unique approaches for upscaling using (a) analytical Monte Carlo techniques and (b) data-mining of complex numerical models.