Assessing hyporheic exchange and associated travel times by hydraulic, chemical, and isotopic monitoring at the Steinlach Test Site, Germany

作者：Osenbrueck Karsten; Woehling Thomas; Lemke Dennis; Rohrbach Nina; Schwientek Marc; Leven Carsten; Alvarez Cristina Castillo; Taubald Heinrich; Cirpka Olaf A

来源：Environmental Earth Sciences, 2013, 69(2): 359-372.

DOI：10.1007/s12665-012-2155-4

• Hyporheic zone
• Stream-groundwater interaction
• Travel time distribution
• Deconvolution
• Monitoring

First results of a multi-disciplinary hyporheic monitoring study are presented from the newly established Steinlach Test Site in Southern Germany. The site is located in a bend of the River Steinlach (mean discharge of 1.8 mA(3)/s) underlain by an alluvial sandy gravel aquifer connected to the stream. The overall objective is a better understanding of hyporheic exchange processes at the site and their interrelations with microbial community dynamics and biochemical reactions at the stream-groundwater interface. The present paper focuses on the distribution of lateral hyporheic exchange fluxes and their associated travel times at the Steinlach Test Site. Water level dynamics in various piezometers correspond to the different domains of hydraulic conductivity in the shallow aquifer and confirms hyporheic exchange of infiltrated stream water across the test site. Hydrochemical compositions as well as increased damping of continuous time series of electrical conductivity (EC) and temperature at the respective piezometers confirmed the inferred distribution of hyporheic flowpaths. Mean travel times ranging from 0.5 days close to the stream to more than 8 days in the upstream part of the test site could be estimated from deconvolution of EC and delta O-18-H2O data. The travel times agree well with the presumed flowpaths. Mg/Ca ratios as well as model fits to the EC and delta O-18 data indicate the presence of an additional water component in the western part of the test site which most likely consists of hillslope water or groundwater. Based on the mean travel times, the total lateral hyporheic exchange flux at the site was estimated to be of the order of 1-2 L/s.

• 出版日期2013-5