Logistic behavior of flux governed by stream-aquifer properties on groundwater-surface water interaction along the streambed

Interaction of groundwater (GW) and surface water (SW), is a complex phenomenon, governed by the hydrological and hydrogeological properties the streambed and the aquifer beneath. Understanding of these interactions is important for both qualitative and quantitative estimation of different processes occurring in the combined ecosystem. This study identifies critical stream-aquifer parameters and attempts to quantify their influence on the flux exchange.

This study models a 2-D, steady-state and homogenous GW-SW model using numerical modelling tool OpenGeoSys (V6). The conceptual setup includes two components - streambed and the aquifer, with six parameters (hydraulic conductivity, thickness and width of each component). The constant head boundary is used to represent stream and no-flow boundary for the aquifer bottom. The study followed a scenario-based numerical modelling approach by simulating different scenarios to capture the effect of the individual parameters. The current work simulates around two thousand simulations for developing the relationship between exchanging flux and stream-aquifer parameters.

The result identified the ratio of streambed conductance () to the aquifer conductance ( is required for the flux estimation. Further analysis indicated that the flux follows a logistic growth. A dimensionless form of this logistic curve is obtained by normalising the flux with the maximum flux obtained from the given set of parameters. The results highlighted the significance of the aquifer parameters for defining the maximum flux. The study could further be extended to a 3D setup and the empirical relation could be verified using the available field data.