Comparison of One and Three Dimensional MODFLOW Subsidence Results

One dimensional subsidence models are often used due to lack of available input data.  While these are useful screening level models, integration of subsidence modeling into a three dimensional flow model should be considered, particularly if a flow model already exists.  MODFLOW SUB-WT and SUB packages rely on the Terzaghi theory of one-dimensional consolidation to calculate subsidence.  Although these calculations are based in the vertical dimension, use of these packages impacts the water balance and subsequent results of groundwater flow models. This presentation will provide details on the differences in model results between one and three dimensional subsidence modeling using the MODFLOW SUB-WT package.