EFFICIENCY IN LAND MANAGEMENT – MAKING USE OF EXISTING GROUNDWATER MODELS TO EVALUATE PLANNED DEVELOPMENTS

There is often a need to evaluate the effects of a project’s groundwater pumping into the future, and development of a new computer simulation is generally cost and time prohibitive. Also, in a land management agency such as the Forest Service, Bureau of Land Management, or Fish and Wildlife Service, there is generally no resource base for obtaining new and detailed hydrogeological data. However, there are often acceptable models which have been developed by other agencies, such as the US Geological Survey (USGS) which may be put to good use. Potential candidate models must be subjected to careful scrutiny to determine whether or not they are appropriate for the intended use. USGS models are often useful because they are often designed with uniform grids, are designed for water supply evaluation, and are generally well researched over the entire model domain. Models with telescoped grids, refined for a specific area of concern, are often less useful because of their cursory information in outer areas that were unimportant to the model’s purpose. Models utilized for evaluating a specific dewatering project or other pumping scenario are often in this category. Useful models in the examples here include the Great Basin Model of Prudic (USGS, 1995), the Tucson Active Management Area groundwater model (ADWR, 2006), and the Redwall-Muav, Coconino, and Alluvial Basin model (USGS, 2011). An inappropriate model used in a water development project near Grants, NM is also shown for comparison. In this model, the area utilized has a very coarse grid, and the hydrogeologic information is sparse. While use of existing models is often convenient and potentially saves time, some investigation into model philosophy and construction should be done to assure that the model is appropriate.