A framework for parameter estimation using sharp-interface seawater intrusion models

Sharp-interface seawater intrusion models present shorter run times than variable density codes, which makes them practical for regional, decision-support groundwater modeling. Although parameter estimation and uncertainty analyses are essential steps model-based decision making, their implementation in has remained limited. Few guidelines available it is unclear observations should be used, what processing they require weighting strategy used. A framework been developed using a regional sharp-interface model applied to real-world example the Magdalen Islands (Quebec, Canada). This included assimilation of head collected from shallow wells, deep open wells pumping as well freshwater-seawater interface derived TDEM (time-domain electromagnetic) ERT (electrical resistivity tomography) geophysical surveys. was MODFLOW-SWI2 fast allowed numerous parameters, including heterogeneous hydraulic conductivity field with pilot points. Following PEST, several forecasts, i.e. volume freshwater elevation near municipal examined first-order second moment (FOSM) approach data worth analysis carried out. While presented low signal-to-noise ratio, effective reduce forecasts. Interface observations, particularly were most useful predictive uncertainties. Head biased could not suitably reproduced by model. The here relatively straightforward implemented more systematically. study also provides recommendations guide future collection strategies coastal aquifers.