Agenda - Council - 07/28/2015 - Laserfiche WebLink

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DATE: March 18, 2015 TO: Water Supply Planning Unit, Metropolitan Council FROM: Anneka Munsell, Environmental Scientist SUBJECT: Metro Model 3 Application: Evaluating 2040 Water Demand Metro Model 3 (MM3) was developed and calibrated to help the Metropolitan Council evaluate the effects of current and future groundwater withdrawals and land use on groundwater levels and the base flows of streams at a regional scale. These types of model predictions are useful for interpreting hydrogeologic data, informing future data collection, and for evaluating alternatives to enhance sustainable use of water resources in the metropolitan area. Metro Model 3 is also available for others to use as starting point for more subregional or localized analyses. For example, with refinement, it can be used for well impact evaluations, capture zone analysis, evaluation of surface water impacts, or to explore the impact of land use changes on recharge. Benefits of this revision of the Metro Model include: • Incorporation of new information, • Implementation of newer and better -supported software, • Enhanced methods to understand parameter sensitivities and uncertainty in model predictions, • Improved representation of Quaternary unconsolidated sediments and their influence on the groundwater -flow system, • The ability to simulate seasonal effects of climatic and pumping stresses, and • An expanded model domain (Barr, Metropolitan Council 2014). Objectives and Application Metro Model 3 was designed to help address a broad range of regional planning questions and to be as flexible as practical in order to accommodate new questions or scenarios, while still incorporating the best available data. Some examples of questions the model is intended to help address include: • Given projected water demands, what impacts may be expected on groundwater levels and groundwater -dependent surface -water features? • What combinations of source aquifers, well locations, and withdrawal rates can be used to achieve sustainable water consumption? • How will projected water demand affect groundwater levels in each aquifer across the metropolitan area? In its current design, MM3 successfully answers these questions. However, interpretation of the model results must recognize that any model is a simplification of a complex system and accuracy is limited by naturally variable geologic conditions and human error in measurements. For more information on MM3