Software & Algorithms
SUTRA 4.0, AKA 'SUTRA-ICE'
SUTRA (Saturated-Unsaturated Transport) is a U.S. Geological Survey hybrid finite element-finite difference code of coupled groundwater flow and energy or solute transport. The next update (version 4.0) will include many new pre-programmed functions and will also allow for ground freeze-thaw. I have been actively involved in the development, benchmarking, and application of this version of the code and am a coauthor of the forthcoming U.S. Geological Survey report. The work is spearheaded by Drs. Cliff Voss and Alden Provost with the Survey and Dr. Jeffrey McKenzie (McGill University). The model will have many exciting applications in Canadian hydrogeology as our permafrost groundwater systems evolve in a warming climate. SUTRA is part of the international cold regions groundwater modeling benchmark initiative known as InterFrost.
Flux-LM (Flux in Layered Media) is a spreadsheet-based tool for quantifying vertical groundwater fluxes in homogenous or heterogeneous (up to four layers) porous media. It fits an analytical solution to temperature profiles using Excel Solver, with the optimal fit obtained by adjusting the Darcy flux. The original paper detailed shallow streambed and aquifer-scale applications, and subsequent work has applied this in deep-ocean seabed thermal profiles. An updated version of the tool for download is available on FigShare.
FAST (Flexible Analytical Solution using Temperature) is a Python program that runs a superimposed analytical solution to investigate the effects of climate change on groundwater temperature. The solution and code can be employed to project future groundwater warming or to trace vertical groundwater flow rates from the evolution of a subsurface temperature profile over the past few decades. FAST was a joint effort with Dr. Dylan Irvine, and the manual and updated code can be found on his site. FAST has been applied in Japan, Australia, and the Netherlands.
Spreadsheet for Seasonal and Decadal Groundwater Temperature Calculations
Shallow aquifers respond thermally to seasonal and multi-decadal changes in climate. These effects can be predicted using simple analytical solutions. Our 2015 open-access paper in Hydrology and Earth System Sciences includes an electronic supplement with a spreadsheet that automates a number of these solutions.
Soil Freeze-Thaw Algorithms
I have been active in the development and verification of algorithms for predicting seasonal freeze-thaw in cold regions. The frost depth in seasonally frozen soils and the thaw depth in permafrost are critical controls in geotechnical engineering and cold-regions hydrology. Developing parsimonious approaches to accurately quantify these depths is essential for computationally efficient large-scale hydrological modeling. Our past work has considered the effects of sensible heat and layered soils on freeze-thaw penetration.