Integrated surface and subsurface hydrologic models (ISSHM) aim to simulate all components of the water cycle that affect surface water and groundwater. The first generation of ISSHMs focused on the simulation of surface water and groundwater fluxes, but current developments include the incorporation of water fluxes between the soil and atmosphere, as well as the coupled simulation of water, energy and mass fluxes. Because ISSHMs attempt to account for all components of the water cycle, they represent powerful tools to support water resources management and address pressing worldwide issues such as increased water use, water pollution, droughts and floods.
Several challenges are associated with the development and application of ISSHMs, such as upscaling or downscaling issues, data availability, model calibration and computational efficiency. Current applications cover a very wide range of spatial and temporal scales and data availability at these various scales can be an issue. The representation of physical processes occurring at scales smaller than the discretization scale, such as water and mass exchange in streambeds, is also a current topic of research. Furthermore, automated calibration and uncertainty analysis of large-scale ISSHMs have seldom been undertaken because of their high computational cost. On the other hand, current research focuses on using non-traditional data and observation types to help inform ISSHMs and improve calibration. This session seeks presentations that address current challenges and current developments of ISSMHs related to coupled processes (water, energy, mass transport) as well as linkages with soil and atmospheric models. We also seek examples of novel applications to demonstrate the potential of ISSHMs to help process understanding and guide water management.