Publication Details

Category Text Publication
Reference Category Journals
DOI 10.1002/2016WR018677
Title (Primary) The effect of losing and gaining flow conditions on hyporheic exchange in heterogeneous streambeds
Author Fox, A.; Laube, G.; Schmidt, C.; Fleckenstein, J.H.; Arnon, S.
Source Titel Water Resources Research
Year 2016
Department HDG
Volume 52
Issue 9
Page From 7460
Page To 7477
Language englisch
Keywords hyporheic exchange flux; heterogeneous streambeds; stream-aquifer interaction; losing stream; gaining stream
UFZ wide themes RU2;
Abstract Bed form-induced hyporheic exchange flux (qH) is increasingly viewed as a key process controlling water fluxes and biogeochemical processes in river networks. Despite the fact that streambeds are inherently heterogeneous, the majority of bed form flume-scale studies were done on homogeneous systems. We conducted salt and dye tracer experiments to study the effects of losing and gaining flow conditions on qH using a laboratory recirculating flume system packed with a heterogeneous streambed, and equipped with a drainage system that enabled us to apply losing or gaining fluxes. We found that when either losing or gaining fluxes increased (regardless of whether the flux was upward or downward), qH followed an exponential decline, the volume of the hyporheic flow cell drastically reduced, and the mean residence times declined moderately. A numerical flow model for the heterogeneous streambed was set up and fitted against the experimental data in order to test whether an equivalent homogeneous case exists. The measured qH were accurately predicted with the heterogeneous model, while it was underestimated using a homogeneous model characterized by the geometric mean of the hydraulic conductivity. It was also shown that in order to produce the results of the heterogeneous model with an equivalent hydraulic conductivity, the latter had to be increased as the losing or gaining fluxes increase. The results strongly suggest that it is critical to adequately account for the heterogeneous streambed structure in order to accurately predict the effect of vertical exchange fluxes between the stream and groundwater on hyporheic exchange.
Persistent UFZ Identifier
Fox, A., Laube, G., Schmidt, C., Fleckenstein, J.H., Arnon, S. (2016):
The effect of losing and gaining flow conditions on hyporheic exchange in heterogeneous streambeds
Water Resour. Res. 52 (9), 7460 - 7477 10.1002/2016WR018677