TY  - JOUR
A1  - Munz, Matthias
A1  - Oswald, Sascha Eric
A1  - Schmidt, Christian
T1  - Analysis of riverbed temperatures to determine the geometry of subsurface water flow around in-stream geomorphological structures
JF  - Journal of hydrology
N2  - The analytical evaluation of diurnal temperature variation in riverbed sediments provides detailed information on exchange fluxes between rivers and groundwater. The underlying assumption of the stationary, one-dimensional vertical flow field is frequently violated in natural systems where subsurface water flow often has a significant horizontal component. In this paper, we present a new methodology for identifying the geometry of the subsurface flow field using vertical temperature profiles. The statistical analyses are based on model optimisation and selection and are used to evaluate the shape of vertical amplitude ratio profiles. The method was applied to multiple profiles measured around in-stream geomorphological structures in a losing reach of a gravel bed river. The predominant subsurface flow field was systematically categorised in purely vertical and horizontal (hyporheic, parafluvial) components. The results highlight that river groundwater exchange flux at the head, crest and tail of geomorphological structures significantly deviated from the one-dimensional vertical flow, due to a significant horizontal component. The geometry of the subsurface water flow depended on the position around the geomorphological structures and on the river level. The methodology presented in this paper features great potential for characterising the spatial patterns and temporal dynamics of complex subsurface flow geometries by using measured temperature time series in vertical profiles. (C) 2016 Elsevier B.V. All rights reserved.
KW  - Temperature time series
KW  - Amplitude ratio
KW  - River-groundwater exchange
KW  - Hyporheic zone
KW  - In-stream geomorphological structures
KW  - River restoration
Y1  - 2016
U6  - https://doi.org/10.1016/j.jhydrol.2016.05.012
SN  - 0022-1694
SN  - 1879-2707
VL  - 539
SP  - 74
EP  - 87
PB  - Elsevier
CY  - Amsterdam
ER  -