Ground Water-Surface Water Interface (GWSWI) Modeling: Recent Advances and Future Challenges

Ground water-surface water interface (GWSWI) represents the interconnection of ground water and surface water in the hydrologic continuum. Interactions between these two water masses result in unique gradients and/or transitions of contaminant concentration profiles, biological populations, chemistry, flow, mixing characteristics, redox potential, dissolved oxygen, organic content, and thermal properties across GWSWI. In addition, many unique biogeochemical processes occur in this zone that can have significant impact on the fate and transport of contaminants across the GWSWI. Prediction of the distribution and concentrations of contaminants across the GWSWI is challenging, but is essential for evaluating human health and environmental risk, including remedial alternatives at contaminated sites. The objective of this paper is to review and assess existing modeling capabilities to recognize (a) the need for development of new modeling tools, (b) knowledge gaps, and (c) challenges required to address contaminant transport within GWSWI. Currently, the most important needs for future model development are, (a) linkage between ground water and surface water models; (b) integration of process-level models within the framework of large-scale models; and (c) understanding ground water-surface water interactions within a spatial and temporal framework.