Hydrologic processes occurring near the land surface, such as precipitation, infiltration, evaporation, transpiration, and runoff, have been historically modeled separately from regional groundwater flow processes. This has been mainly due to large differences in time scales associated with flow within these flow domains. Watershed-runoff models simulate near-surface hydrology in great detail, but greatly simplify or completely neglect subsurface flow. Similarly, regional groundwater models often simplify near-surface hydrologic processes by specifying groundwater recharge based on external calculations independent of groundwater levels. Modeling flow through the unsaturated zone has been a major obstacle to coupling watershed-runoff and regional groundwater flow models. There has recently been considerable effort spent in coupling these independent models, to develop integrated modeling tools that could fully characterize interactions among surface, vadose zone, and groundwater flow.

In this session, contributions are invited that focus on applying and developing new modeling tools that enable evaluation of interactions in complex systems involving surface water, vadose zone water, and groundwater. Contributions may also include studies related to transport of nutrients and various contaminants.