The Adaptive Hydraulics (AdH) software suite is a flagship, DoD-wide, high fidelity, finite element resource for 2D and 3D shallow water (SW) modeling, overland flow, groundwater and transport applications. It supports a host of features vital to most hydraulic and transport-engineering applications, including for example, spatial and temporal adaption, surface wave and wind-wave stress coupling, flow through hydraulic structures (weirs, flap gate, etc.) and vessel flow interactions. The AdH suite is also internally linked to a number of process-oriented libraries for cohesive/non-cohesive sediment transport, meteorological forcing and friction and turbulence applications. Recently, the AdH framework was redesigned to allow for monolithic coupling of the software’s internal models. The coupling mechanism is both conservative and easy to implement from a front-end perspective. In this talk we specifically present the coupling formulation between AdH’s 2D and 3D SW and transport models along with verification and validation results. The primary motive behind 2D/3D SW coupling is (1) to improve the efficiency of 3D baroclinic applications by approximating some part of the global domain as 2D and (2) to incorporate wetting and drying regions into 3D SW domains.