USGS Hydrologic modeling software

United States Geological Survey (USGS) models are widely used to predict the responses of hydrological systems to changing stresses, such as increasing precipitation or groundwater pumping rates, as well as to predict the fate and movement of solutes and contaminants in water, characteristics of great importance for agricultural production. Within the software is the single water hydrological flow model (MF-OWHM) which is an integrated hydrological flow model. MF-OWHM is designed for the analysis of a wide range of joint use problems, MF-OWHM enables the simulation, analysis and management of human and natural water movement within a physically based supply and demand framework. Another software is the MODPATH Observation Process (MODPATH-OBS) which is a program developed to calculate simulated equivalents to carry observations derived from simulated particle tracking with or without field measurements for a variety of common field situations or hydrological environments. The method can be used for steady-state and transient flow simulations. There is also the Cascade Routing Tool (CRT) which is a computer application for watershed models that includes the coupled surface and groundwater flow model and the precipitation and runoff modeling system ( PRMS, for its acronym in English). CRT generates output to define cascading surface and subsurface flow trajectories for grid-based model domains. Finally there is INFIL3.0, which is perhaps the most important for agriculture since it is a deterministic water balance model based on grids and distributed parameters that calculates the temporal and spatial distribution of daily net water infiltration through the lower limit of the root zone. The bottom of the root zone is the maximum estimated depth below the soil surface affected by evapotranspiration. In many field applications, net infiltration below the bottom of the root zone can be assumed to be equivalent to net recharge of an aquifer from the underlying water table. The daily water balance simulated by INFIL3.0 includes precipitation in the form of rain or snow; snowfall accumulation, sublimation and melting; infiltration into the root zone; evapotranspiration from the root zone; drainage and redistribution of water content within the root zone profile; surface water runoff to and from adjacent grid cells; and net infiltration through the bottom of the root zone.