Coastal regions experience a wide range of water hazards (e.g. flooding, inundation, drought) and stresses which affect a large number of populations globally. Coastal regions are also among the most dynamic areas and it is generally difficult to simulate the complex interactions of the hydrologic system. In this research, 1km-resolution domain covering the Delaware (46,680 km²) and Susquehanna (71,223 km²) river basins, located at the mid-Atlantic region, is built to examine the role of groundwater surface water interaction in the river systems of these coastal basins. We apply the integrated hydrologic model ParFlow-CLM to simulate water and energy fluxes from the bedrock to the top of the canopy. Here we present the development of the model, as well as an analysis of the primary controls of groundwater configuration and groundwater surface water exchanges in this system based on a steady state analysis. We compare our integrated hydrologic approach to another integrated hydrologic model Amanzi-ATS and to E3SM land surface model in order to evaluate the sensitivity of groundwater-surface water interactions to model configuration. This work is the start of a larger model intercomparison project for coastal domains through the Department of Energy Integrated Coastal Modeling Project. In addition to our preliminary comparisons we will present our plans for transient model intercomparison to better understand drought propagation and hydrologic response to extreme events in the mid-Atlantic coastal region.