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From streambed temperature measurements to spatial‐temporal flux quantification: using the LPML method to study groundwater–surface water interaction
Author(s) -
Anibas Christian,
Schneidewind Uwe,
Vandersteen Gerd,
Joris Ingeborg,
Seuntjens Piet,
Batelaan Okke
Publication year - 2015
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.10588
Subject(s) - environmental science , biogeochemical cycle , hyporheic zone , groundwater , hydrology (agriculture) , spatial variability , tracer , surface water , aquifer , streams , flux (metallurgy) , groundwater discharge , temporal scales , atmospheric sciences , soil science , groundwater flow , geology , environmental chemistry , chemistry , environmental engineering , geotechnical engineering , mathematics , computer network , ecology , computer science , biology , nuclear physics , statistics , physics , organic chemistry
Knowledge on groundwater–surface water interaction and especially on exchange fluxes between streams and aquifers is an important prerequisite for the study of transport and fate of contaminants and nutrients in the hyporheic zone. One possibility to quantify groundwater–surface water exchange fluxes is by using heat as an environmlental tracer. Modern field equipment including multilevel temperature sticks and the novel open‐source analysis tool LPML make this technique ever more attractive. The recently developed LPML method solves the one‐dimensional fluid flow and heat transport equation by combining a local polynomial method with a maximum likelihood estimator. In this study, we apply the LPML method on field data to quantify the spatial and temporal variability of vertical fluxes and their uncertainties from temperature–time series measured in a Belgian lowland stream. Over several months, temperature data were collected with multilevel temperature sticks at the streambed top and at six depths for a small stream section. Long‐term estimates show a range from gaining fluxes of −291 mm day −1 to loosing fluxes of 12 mm day −1 ; average seasonal fluxes ranged from −138 mm day −1 in winter to −16 mm day −1 in summer. With our analyses, we could determine a high spatial and temporal variability of vertical exchange fluxes for the investigated stream section. Such spatial and temporal variability should be taken into account in biogeochemical cycling of carbon, nutrients and metals and in fate analysis of contaminant plumes. In general, the stream section was gaining during most of the observation period. Two short‐term high stream stage events, seemingly caused by blockage of the stream outlet, led to a change in flow direction from gaining to losing conditions. We also found more discharge occurring at the outer stream bank than at the inner one indicating a local flow‐through system. With the conducted analyses, we were able to advance our understanding of the regional groundwater flow system. Copyright © 2015 John Wiley & Sons, Ltd.