Snowmelt-induced diel fluxes through the hyporheic zone

[1] Snowmelt processes result in diel fluctuations in streamflow and stream stage that propagate into riparian aquifers and cause a daily pumping of the hyporheic zone. This diel pumping was observed in stream stage and water table records collected in Tuolumne Meadows, Yosemite National Park, California. A model was developed using Fourier analysis to represent the stream stage fluctuations and a solution to the 1-D, linearized Boussinesq equation for groundwater flow. The modeling demonstrates that a substantial volume of water is pumped in and out of the aquifer via this process on a daily basis. In addition, since the snowmelt-induced groundwater fluctuations exhibit both reduced amplitudes and increased time lags at distances away from the stream, the model can be used to estimate the hydraulic parameters of the riparian aquifer. Snowmelt-induced hyporheic pumping may have implications for biogeochemical processes in the hyporheic zone and may provide important ecosystem services related to water filtration, thermal buffering, nutrient cycling, and water quality. Consideration should be given to recognizing, quantifying, and monitoring snowmelt-induced pumping of the hyporheic zone and the ecosystem services it provides since climate and land use changes may alter the magnitude of this process in the future.