Simulating coupled surface–subsurface flows with ParFlow v3.5.0: capabilities, applications, and ongoing development of an open-source, massively parallel, integrated hydrologic model

• Published in: Geoscientific Model Development Vol. 13; no. 3; pp. 1373 - 1397
• Main Authors: Kuffour, Benjamin N. O, Engdahl, Nicholas B, Woodward, Carol S, Condon, Laura E, Kollet, Stefan, Maxwell, Reed M
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 23-03-2020; European Geosciences Union; Copernicus Publications
• Subjects: Approximation; Aquatic reptiles; Atmospheric models; Computer simulation; Connectors; Couplings; Finite difference method; Finite volume method; Flow simulation; GEOSCIENCES; Groundwater; Groundwater flow; Hydraulic flow; Hydraulics; Hydrologic models; Hydrology; Kinematic waves; Laboratories; Multigrid methods; Multiprocessing; Nonlinear systems; Overland flow; Permeability; Saturated flow; Shallow water; Shallow water equations; Subsurface flow; Surface flow; Surface runoff; Surface water; Technology; Technology application; Three dimensional flow; Time; Two dimensional flow; Watershed management; Watersheds; United States > US; Colorado
• ISSN: 1991-9603; 1991-959X; 1991-962X; 1991-9603; 1991-962X
• DOI: 10.5194/gmd-13-1373-2020

Surface flow and subsurface flow constitute a naturally linked hydrologic
continuum that has not traditionally been simulated in an integrated
fashion. Recognizing the interactions between these systems has encouraged
the development of integrated hydrologic models (IHMs) capable of treating
surface and subsurface systems as a single integrated resource. IHMs are
dynamically evolving with improvements in technology, and the extent of their
current capabilities are often only known to the developers and not general
users. This article provides an overview of the core functionality,
capability, applications, and ongoing development of one open-source IHM,
ParFlow. ParFlow is a parallel, integrated, hydrologic model that simulates
surface and subsurface flows. ParFlow solves the Richards equation for
three-dimensional variably saturated groundwater flow and the
two-dimensional kinematic wave approximation of the shallow water equations
for overland flow. The model employs a conservative centered finite-difference scheme and a conservative finite-volume method for subsurface
flow and transport, respectively. ParFlow uses multigrid-preconditioned
Krylov and Newton–Krylov methods to solve the linear and nonlinear systems
within each time step of the flow simulations. The code has demonstrated
very efficient parallel solution capabilities. ParFlow has been coupled to
geochemical reaction, land surface (e.g., the Common Land Model), and atmospheric
models to study the interactions among the subsurface, land surface, and
atmosphere systems across different spatial scales. This overview focuses on
the current capabilities of the code, the core simulation engine, and the
primary couplings of the subsurface model to other codes, taking a
high-level perspective.