On the value of surface saturated area dynamics mapped with thermal infrared imagery for modeling the hillslope-riparian-stream continuum

Abstract

The highly dynamic processes within a hillslope-riparian-stream (HRS) continuum are known to affect streamflow generation, but are yet not fully understood. Within this study, we simulated a headwater HRS continuum in western Luxembourg with an integrated hydrologic surface subsurface model (HydroGeoSphere). The model was setup with thorough consideration of catchment-specific attributes and we performed a multicriteria model evaluation (4 years) with special focus on the temporally varying spatial patterns of surface saturation. We used a portable thermal infrared (TIR) camera to map surface saturation with a high spatial resolution and collected 20 panoramic snapshots of the riparian zone (approx. 10 m 3 20 m) under different hydrologic conditions. Qualitative and quantitative comparison of the processed TIR panoramas and the corresponding model output panoramas revealed a good agreement between spatiotemporal dynamic model and field surface saturation patterns. A double logarithmic linear relationship between surface saturation extent and discharge was similar for modeled and observed data. This provided confidence in the capability of an integrated hydrologic surface subsurface model to represent temporal and spatial water flux dynamics at small (HRS continuum) scales. However, model scenarios with different parameterizations of the riparian zone showed that discharge and surface saturation were controlled by different parameters and hardly influenced each other. Surface saturation only affected very fast runoff responses with a small volumetric contribution to stream discharge, indicating that the dynamic surface saturation in the riparian zone does not necessarily imply a major control on runoff generation.

Diel fluctuations of viscosity-driven riparian inflow affect streamflow DOC concentration

“…We valid index of higher terrestrial and SUVA-254 rapidly increased. (Glaser et al, 2016;Klaus et al, 2015). was induced by terrestrial DOC input that eventually led to a For the days with diel fluctuations we reject our first hypothesis that the instream processes.…”

“…For the combinations that included discharge, we generally observed weaker and more heterogeneous relationships (Figure 3 c,e,f and he Weierbach catchment, we are convinced that SUVAidentifying terrestrial DOC in diel DOC fluctuations. Several studies already demonstrated that SUVA (Catalán et al, 2013;Fasching et al, 2016;Lee et al, 2016;Weishaar et al catchment for rising SUVA-254 values serving as a valid index Immediately after rain events, discharge, DOC concentrations and SUVA surface or near-surface runoff processes (Glaser et al, 2016;Klaus et al, 2015) the increase in DOC concentrations was induced by terrestrial DOC input that s on processes controlling diel DOC fluctuations. For the days with diel fluctu generally observed both DOC and SUVA-254 maxima in the afternoon.…”

“…During the observation period, no substantial snowfall was observed. The annual rainfall runoff ratio was around 50% with higher discharge volumes in winter than in summer (Glaser et al, 2016;Martínez-Carreras et al, 2015;Pfister et al, 2017;Schwab et al, 2016).…”

Exploring Streamwater Mixing Dynamics via Handheld Thermal Infrared Imagery

“…To date, airborne and ground-based TIR imagery have been successfully used to describe longitudinal profiles of river temperature [27][28][29][30], to provide information on soil moisture and surface saturation patterns [31,32], to detect ground water exfiltration along the hillslope-riparian-stream continuum and inferring connectivity dynamics of water exfiltrating to the stream [33][34][35][36][37]. Furthermore, information obtained through TIR imagery has been used as a data source for hydrological model validation [32,38]. Thus far, the potential for handheld TIR imagery to assess water mixing dynamics in small streams has not been fully assessed [23,25,35,39], with the vast majority of the studies relying on airborne TIR observations or reporting only some marginal observations specifically on water mixing.…”

How runoff components affect the export of DOC and nitrate: a long-term and high-frequency analysis

“…The Weierbach catchment shows a dynamic combination of fast and delayed rainfall-runoff reactions, thus high-frequency monitoring has the potential for capturing the entire range of runoff processes, the resulting runoff components and related (Glaser et al, 2016;Klaus et al, 2015;Martínez-Carreras et al, 2016a;Pfister et al, 2017;Schwab et al, 2016). 15 The DOC and nitrate concentrations in the Weierbach creek were measured in-situ with the UV-Vis spectrometer spectro::lyser (s::can Messtechnik GmbH).…”