This document summarizes a presentation on developing a dimensionally-reduced model for coupled river-subsurface flow modeling. It describes: 1) The need for an integrated model to simulate flow in a mountainous catchment with steep slopes and deep bedrock. 2) A new model that reduces the dimensionality of the 3D Richards equation to simplify simulations while remaining physically-based. 3) Validation of the reduced model against a full 3D Richards model on a 2D cross-section, showing good agreement in water table elevations. 4) Plans to test the coupled reduced model on the instrumented Strengbach catchment to better characterize flow pathways and residence times.