MODFLOW-OWHM: One Water Hydrologic Flow Model
The One-Water Hydrologic Flow Model (MF-OWHM) (Hanson and others, 2014) is a MODFLOW-based integrated hydrologic flow model (IHM) that is the most complete version, to date, of the MODFLOW family of hydrologic simulators needed for the analysis of a broad range of conjunctive-use issues. Conjunctive use is the combined use of groundwater and surface water. MF-OWHM allows the simulation, analysis, and management of nearly all components of human and natural water movement and its use in a physically-based supply-and-demand framework.
MF-OWHM is based on the Farm Process for MODFLOW-2005 (MF-FMP2, Schmid and Hanson, 2009) that is now combined with Local Grid Refinement (LGR, Mehl and Hill, 2013) for embedded models to allow use of the Farm Process (FMP) and Streamflow Routing (SFR) within embedded grids. MF-OWHM also now includes new features such as the Surface-water Routing Process (SWR, Hughes and others, 2012), Seawater Intrusion (SWI, Bakker and others, 2013), and Riparian Evapotranspiration (RIP-ET, Maddock III and others, 2012). MF-OWHM contains all the previously available solvers and the new solvers such as Newton-Raphson (NWT, Niswonger and others, 2011) and the nonlinear preconditioned conjugate gradient (PCGN, Naff and Banta, 2008).
What makes MF-OWHM unique is that it allows the simulation of head-dependent flows, flow-dependent flows, and deformation dependent flows that collectively affect conjunctive use of water resources. The supply-constrained and demand-driven framework combined with the linkages between packages and processes provides relations of water use and movement, and helps to prevent mass loss to an open system thus facilitating the accounting for "all of the water everywhere and all of the time."