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United States Department of Agriculture

Agricultural Research Service

Title: The Simultaneous Heat and Water (Shaw) Model: a Research Tool for Management Decisions

Authors
item Flerchinger, Gerald
item Hardegree, Stuart
item Johnson, Greg - USDA NRCS

Submitted to: Federal Interagency Hydrologic Modeling Conference
Publication Type: Proceedings
Publication Acceptance Date: November 7, 1997
Publication Date: N/A

Interpretive Summary: As computer simulation models become increasingly sophisticated, their ability to address complex problems is enhanced. Unfortunately, complex models are typically associated with complex input requirements and difficult interpretation of model results. Thus, as research models become more complex, the gap widens between models developed by researchers and models that a natural resource manager can use as a practical tool to make informed decisions. However, input requirements can be simplified through development of a user-friendly interface to aid the user in applying the model. The detailed physics in the SHAW model coupled with its user-interface (ModShell for Model Shell) make it a useful tool to address many potential applications, including such complex problems as: runoff related to seasonally frozen soils; surface energy and water balance; percolation to ground water; evapotranspiration and water use by competing plant; and near-surface temperature and water conditions for such processes as seedling germination and insect population dynamics. This ability enables natural resource managers to evaluate various management scenarios to make better-informed decisions which can lead to considerable cost savings. Two such applications of the SHAW model as a decision aid tool are presented in this paper.

Technical Abstract: The Simultaneous Heat and Water (SHAW) Model, originally developed to simulate soil freezing and thawing simulates heat, water and solute transfer near the soil surface. The flexibility and detailed physics incorporated into the SHAW model give it the ability to accurately simulate temperature, water and solute conditions from a myriad of applications including such complex problems as: runoff related to seasonally frozen soils; surface energy and water balance; percolation to ground water; evapotranspiration and plant water use by competing plants; and near-surface temperature and water conditions for such processes as seedling germination, plant establishment, and insect population dynamics. This ability enables natural resource managers to evaluate various management scenarios to make better-informed decisions which can lead to considerable cost savings. Two such applications of the SHAW model as a decision aid tool are presented in this paper. The first application used the SHAW model to simulate temperature and water conditions at the soil surface to assess the effects of climatic variability on establishment of native grass species after wildfire. In the second application, the model provided information to assess the potential risk posed by the migration of contaminants from an abandoned landfill site; the soil water balance, percolation to ground water, and contaminant transport were simulated at the site.

Last Modified: 10/19/2014
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