Hyporheic exchange studies in H.J. Andrews Watersheds 01 and 03, summer 2010

A series of hyporheic exchange studies were conducted in watersheds 01 and 03 during the summer of 2010 using saline tracers coupled with electrical resistivity to image the temporal and spatial extent of the hyporheic zone during baseflow recession. A series of four 48-hr tracer tests were conducted in each watershed on a rotational schedule with each tracer test starting approximately 2 weeks following the start of the previous test in each watershed. Each tracer injection was targeted to enrich the stream electrical conductivity by ~100 uS/cm. Electrical resistivity surveys were conducted on up to 6 transects of electrodes (12 electrodes per transect) in each watershed for each test. Resistivity surveys were collected, on a high temporal frequency ranging from continuous to every 4 hrs, for pre-injection, injection, and post-injection until conductivity measurements in the shallow groundwater well network returned to pre-injection magnitudes. During each injection conductivity magnitudes were measured in the stream and each accessible groundwater well in the watershed using a handheld conductivity meter on a frequency ranging from near continuous (~15-30 min), during tracer start-up and shutoff, to every 2-6 hrs depending on position within the tracer test. Hydraulic head data was collected approximately every 15 minutes by downwell pressure transducers from a select set of groundwater wells in each watershed for nearly the full summer 2010.

These data were published in a series of papers outlined below.