Summary of the work that generated the associated data: Hydroelectric dams often create highly dynamic downstream flows that promote surface water-groundwater (SW-GW) interactions including bank storage, the temporary storage of river water in the riverbank. Previous research on SW-GW exchanges in dammed rivers have been local studies conducted within the bed or the bank, limiting the understanding of these exchanges which occur over potentially hundreds of kilometers. This study evaluates how dam releases affect SW-GW exchange continuously over a 100 km distance. This is accomplished by longitudinally routing water releases through a synthetic river and modeling bed and bank fluid and solute exchange across transverse transects spaced along the reach. Peak and square dam release hydrograph shapes with three magnitudes (0.5, 1.0, and 1.5 m) were considered. The effect of four ambient groundwater flow conditions (very slightly losing, neutral, and two gaining from the perspective of the river) were evaluated for each dam release scenario. Both types of dam release shapes cause SW-GW interaction over the entire 100 km distance, and our results show square type releases cause bank storage exchange well beyond this distance. Strongly gaining conditions reduce the amount of exchange and allow flushing of river-sourced solute out of the bank after the dam pulse has passed. Both neutral and losing conditions have larger fluid and solute flux into the bank and limit the amount of solute that returns to the river. Our results support that river corridors downstream of dams have increased river-aquifer connectivity, and that this enhanced connectivity can extend at least 100 km downstream.

This page has the following data:
-Copy of Comsol model that was used to generate bank storage exchange fluid flux and solute area (hyporheic zone size) results
-Data file of dam release boundary conditions used for the HEC-RAS routing model
-Time series of river hydrograph (depth) response at 1 km resolution. The data provided is for the results to the six dam release scenarios considered in this study exported from HEC-RAS models. Time is on x-axis and distance along river on y axis. The dam is located at river kilometer (rkm) 200 and descending distance indicates further downstream distance.
-All model output results from Comsol models - these include time series of both fluid flux rates across the river-channel boundary and the size of the hyporheic zone based on percentage of river water in the subsurface.