HR: 1340h
AN: H23A-1012    [Abstracts]
TI: How Streambed Temperatures can Contribute to the Determination of Aquifer Heterogeneity
AU: Kalbus, E
EM: edda.kalbus@ufz.de
AF: UFZ - Helmholtz Centre for Environmental Research, Department of Hydrogeology, Permoserstrasse 15, Leipzig, 04318, Germany
AU: * Schmidt, C
EM: christian.schmidt@ufz.de
AF: UFZ - Helmholtz Centre for Environmental Research, Department of Hydrogeology, Permoserstrasse 15, Leipzig, 04318, Germany
AU: Reinstorf, F
EM: frido.reinstorf@ufz.de
AF: UFZ - Helmholtz Centre for Environmental Research, Department of Hydrogeology, Permoserstrasse 15, Leipzig, 04318, Germany
AU: Schirmer, M
EM: mario.schirmer@ufz.de
AF: UFZ - Helmholtz Centre for Environmental Research, Department of Hydrogeology, Permoserstrasse 15, Leipzig, 04318, Germany
AB: The groundwater discharge to a stream may show small-scale heterogeneities caused by the structure of the connected aquifer. Traditional subsurface investigation techniques are often not capable of providing data in sufficient resolution to capture these small-scale variations in aquifer properties. In the streambed, the spatial pattern of the groundwater discharge can be investigated by temperature measurements. We hypothesize that the heterogeneity of the hydraulic conductivity (K) of an aquifer can be inferred from measured streambed temperatures. At a 220 m long section of a small stream in Germany, streambed temperatures were mapped with high resolution. A groundwater flow and heat transport model of the stream-aquifer system was set up including stochastically generated K fields. Direct-push injection logs and slug tests were performed in the connected aquifer to obtain the mean, variance and correlation lengths of K. Yet, the model results showed that the simulated streambed temperatures did not cover the range of measured temperatures. We concluded that the calculated variance of K was too low to cause the observed heterogeneities of the streambed temperatures and therefore generated new K fields with varying variances. From the model results we analyzed the relation between the variances of K and the simulated distribution of streambed temperatures. The required variance of K to reproduce the range of measured streambed temperatures could then be determined from this relation. From realizations of K fields generated with the adjusted variance, several could be selected that induced a range of groundwater fluxes and streambed temperatures in the model similar to the measured range. With the selected realizations the spatial distribution of groundwater fluxes in relation to the streambed area could also be well reproduced. Accordingly, these K fields are reliable input data for further modeling applications. This study showed that subsurface characterization methods based on heat constitute a valuable supplement to traditional exploration techniques.
DE: 1830 Groundwater/surface water interaction
DE: 1832 Groundwater transport
DE: 1835 Hydrogeophysics
DE: 1847 Modeling
DE: 1869 Stochastic hydrology
SC: Hydrology [H]
MN: 2007 Fall Meeting