ENHANCING INTEGRATED WATER MANAGEMENT IN THE LOWER PLATTE RIVER BASIN THROUGH SUB-REGIONAL GROUNDWATER MODELING WITH MODFLOW-6 AND AEM GEOLOGIC DATA

Nebraska Department of Natural Resources (NeDNR) works with local Natural Resources Districts (NRDs) to manage regional water supplies in the near and long-term. Nebraska’s integrated water management involves local, regional, and state water managers and employs the best available science to analyze the impacts of water use and evaluate the effectiveness of water management activities. Across the State of Nebraska, NeDNR has focused on modeling groundwater at the regional scale. This approach is effective across non-glaciated areas of Nebraska. In the eastern portions of the Lower Platte River Basin, the highly complex geology resulting from repeated glaciation events is difficult to model at the regional scale while also representing the local geologic complexity using MODFLOW-2005. However, MODFLOW-6’s enhanced solver, more flexible framework, coupled model utility, and grid refinement capabilities have been critical to integrating recent airborne electromagnetic (AEM) surveys into sub-regional models with finer, more observation-based geologic representation. NeDNR is working with Lower Elkhorn NRD (LENRD) to finalize and test such a sub-regional model and is working to develop additional sub-regional models in other areas of interest. This new groundwater modeling framework will provide NeDNR, the NRDs, and local water managers a more detailed assessment of available water supplies, impacts of water use, and an improved understanding of the Lower Platte River Basin hydrologic system.