Multiple timescales of streambed flux variability in two perennial mountain-front streams

Streambed fluxes are highly variable through time and space, having a range of implications for stream‐aquifer processes. This study investigated streambed fluxes over a 3‐year study period to characterize short‐ and long‐term variations and related implications for seepage recharge and hyporheic exchange. Time series of streambed fluxes were estimated through Darcy‐based methods using water level and temperature inputs from shallow (<1.5 m) nested streambed piezometers installed in two mountain‐front streams in Colorado, USA. Three predominant temporal scales of variability were characterized: sub‐daily (<1 day), daily (>1 day; <1 year), and interannual (>1 year). Temporal variability was quantified using the median absolute deviation (MAD), a statistical measure that is resistant to extreme values associated with short‐duration events. Sub‐daily variability (MADS‐D) was related to ET, temperature‐induced changes in hydraulic conductivity, and variable stream stage, and ...