Temporal geophysical investigation of J-hook induced changes to the hyporheic zone in a fine-grained streambed

In combination with a saline tracer, temporal Electrical Resistivity Imaging (ERI) is an effective tool to analyze the structure of the hyporheic zone. A saline solution was added to the streambed upstream of a J-hook rock vane in a fine-grained stream (Cow Creek, Stillwater, OK) in order to assess the effect of an in-stream rehabilitation structure on hyporheic flow. Three transects were employed, one longitudinal and two transverse, across and downstream of the J-hook. Wells were used to monitor electrical conductivity of the hyporheic zone. The results indicate that the in-stream rehabilitation structures promote and increase hyporheic flow, even streams with fine-grained sediments. Furthermore, hyporheic zones in fine-grained sediments are as active as those in coarse-grained systems. In the temporal ER data, a flow path exists beneath the J-hook; this is evident in all three datasets. A possible effect from hyporheic flow through fine sediments could be increased pollutant retention, due to the ease of surface water pollutants permeating low-K zones beneath these streambeds.