The Little Plover River groundwater flow model simulates three-dimensional groundwater movement in and around Wisconsin’s Little Plover River basin under steady-state and transient conditions. The groundwater flow model uses the U.S. Geological Survey’s MODFLOW-NWT modeling code. This model explicitly includes all high-capacity wells in the model domain and simulates seasonal variations in recharge and well pumping. The model represents the Little Plover River, and other significant streams and drainage ditches in the model domain, as fully connected to the groundwater system, computes stream base flow resulting from groundwater discharge, and routes the flow along the stream channel. A separate soil-water-balance (SWB) model was used to develop a groundwater recharge array as input for the groundwater flow model. The SWB model uses topography, soils, land use, and climatic data to estimate recharge as deep drainage from the soil zone. The SWB model explicitly includes recharge originating as irrigation water, and computes irrigation using techniques similar to those used by local irrigation operators.

he groundwater flow model was calibrated to monthly stress periods with time steps ranging from 1 to 16 days. The groundwater model was calibrated to water-level and streamflow data collected during 2013 and 2014 by adjusting model parameters (primarily hydraulic conductivity, storage, and recharge) until the model produced a conditionally optimal fit between field observations and model output, subject to consistency with previous published geologic studies. Calibration was performed under both steady and transient conditions and used a sophisticated parameter-estimation procedure (PEST) for the calibration process and to identify important model parameters.
With respect to the Little Plover River the two most important parameters are the global recharge multiplier and the hydraulic conductivity of the stream bed. The calibrated model produces water level and mass balance results that are consistent with field observations and with previous studies of the area. This USGS data release contains all of the input and output for the simulations described in the published report which can be found in the main directory of this data release.