Hillslope threshold response to rainfall: (1) A field based forensic approach

Graham, C. B.; Woods, Ross; McDonnell, Jeffrey J.

doi:10.1016/j.jhydrol.2009.12.015

Cited by 171 publications

(177 citation statements)

References 38 publications

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“…Similarly high preferential flow velocities are reported for the well-studied MaiMai hillslope, with initial breakthrough velocities between 6.7×10 −3 and 3.3 × 10 −2 m s −1 , being at least 2 orders of magnitude higher than matrix flow, which ranges between 3.8 × 10 −6 and 1.04 × 10 −4 m s −1 (Graham et al, 2010). Various studies report a concentration of lateral preferential flow at a more or less impermeable bedrock interface for other sites (e.g., Graham et al, 2010;Tromp-Van Meerveld and McDonnell, 2006), which has also been hypothesized for the Colpach River catchment (e.g., Fenicia et al, 2014). However, none of the piezometers showed a significant reaction, despite being installed at the depths with the highest observed soil moisture responses.…”

Section: Irrigation Experimentssupporting

confidence: 72%

“…The order of magnitude of the response velocities agreed with the in situ measurements of hydraulic conductivity (up to 10 −3 m s −1 and higher), but clearly ex-ceeded the potential of matrix flow for the silty matrix material (Jackisch et al, 2017). Similarly high preferential flow velocities are reported for the well-studied MaiMai hillslope, with initial breakthrough velocities between 6.7×10 −3 and 3.3 × 10 −2 m s −1 , being at least 2 orders of magnitude higher than matrix flow, which ranges between 3.8 × 10 −6 and 1.04 × 10 −4 m s −1 (Graham et al, 2010). Various studies report a concentration of lateral preferential flow at a more or less impermeable bedrock interface for other sites (e.g., Graham et al, 2010;Tromp-Van Meerveld and McDonnell, 2006), which has also been hypothesized for the Colpach River catchment (e.g., Fenicia et al, 2014).…”

Section: Irrigation Experimentssupporting

confidence: 70%

“…Hillslope-scale excavations yield information on spatial extent and characteristics of preferential flow paths in 3-D (Anderson et al, 2009;Graham et al, 2010), but are highly destructive and lack the temporal component. Hillslope-scale tracer experiments in contrast resolve temporal dynamics and velocities (Wienhofer et al, 2009;McGuire and McDonnell, 2010) but lack the spatial information.…”

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confidence: 99%

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Form and function in hillslope hydrology: characterization of subsurface flow based on response observations

Angermann

Jackisch

Allroggen

et al. 2017

Hydrol. Earth Syst. Sci.

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Abstract. The phrase form and function was established in architecture and biology and refers to the idea that form and functionality are closely correlated, influence each other, and co-evolve. We suggest transferring this idea to hydrological systems to separate and analyze their two main characteristics: their form, which is equivalent to the spatial structure and static properties, and their function, equivalent to internal responses and hydrological behavior. While this approach is not particularly new to hydrological field research, we want to employ this concept to explicitly pursue the question of what information is most advantageous to understand a hydrological system. We applied this concept to subsurface flow within a hillslope, with a methodological focus on function: we conducted observations during a natural storm event and followed this with a hillslope-scale irrigation experiment. The results are used to infer hydrological processes of the monitored system. Based on these findings, the explanatory power and conclusiveness of the data are discussed. The measurements included basic hydrological monitoring methods, like piezometers, soil moisture, and discharge measurements. These were accompanied by isotope sampling and a novel application of 2-D time-lapse GPR (ground-penetrating radar). The main finding regarding the processes in the hillslope was that preferential flow paths were established quickly, despite unsaturated conditions. These flow paths also caused a detectable signal in the catchment response following a natural rainfall event, showing that these processes are relevant also at the catchment scale. Thus, we conclude that response observations (dynamics and patterns, i.e., indicators of function) were well suited to describing processes at the observational scale. Especially the use of 2-D time-lapse GPR measurements, providing detailed subsurface response patterns, as well as the combination of stream-centered and hillslope-centered approaches, allowed us to link processes and put them in a larger context. Transfer to other scales beyond observational scale and generalizations, however, rely on the knowledge of structures (form) and remain speculative. The complementary approach with a methodological focus on form (i.e., structure exploration) is presented and discussed in the companion paper by Jackisch et al. (2017).

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Section: Irrigation Experimentssupporting

confidence: 72%

Section: Irrigation Experimentssupporting

confidence: 70%

mentioning

confidence: 99%

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Form and function in hillslope hydrology: characterization of subsurface flow based on response observations

Angermann

Jackisch

Allroggen

et al. 2017

Hydrol. Earth Syst. Sci.

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“…Assuming slow development processes of a talus-derived rock glacier, preexisting water flow paths or newly evolving ones will probably prevent sedimentation of fine-grained sediments or wash them out, therefore leaving a channel network of unknown extent between patchily distributed sediment accumulations of lower hydraulic conductivity. Graham et al (2010) showed at excavations of a hillslope watershed that a network of preferential flow paths occurred at the soil-bedrock boundary, which was controlled by the bedrock topography. Scenario vi shows that with such a channel network even a single-layered model can reproduce the discharge dynamics of the SEQ reasonably well, and the fit of the simulated hydrograph could be even further optimized by adjusting the number and extent of the channels.…”

Section: Discussionmentioning

confidence: 99%

“…Another explanation might be the existence of preferential flow paths. Preferential flow paths related to cracks in the soil and roots of plants have been observed at hillslopes (e.g., Graham et al 2010). Similarly, rapid localized flow through solution conduits is well known from karst aquifers (e.g., Worthington 2009).…”

Section: Introductionmentioning

confidence: 95%

Investigating groundwater flow components in an Alpine relict rock glacier (Austria) using a numerical model

Pauritsch¹,

Wagner

Winkler

et al. 2016

Hydrogeol J

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Relict rock glaciers are complex hydrogeological systems that might act as relevant groundwater storages; therefore, the discharge behavior of these alpine landforms needs to be better understood. Hydrogeological and geophysical investigations at a relict rock glacier in the Niedere Tauern Range (Austria) reveal a slow and fast flow component that appear to be related to the heterogeneous structure of the aquifer. A numerical groundwater flow model was used to indicate the influence of important internal structures such as layering, preferential flow paths and aquifer-base topography. Discharge dynamics can be reproduced reasonably by both introducing layers of strongly different hydraulic conductivities or by a network of highly conductive channels within a low-conductivity zone. Moreover, the topography of the aquifer base influences the discharge dynamics, which can be observed particularly in simply structured aquifers. Hydraulic conductivity differences of three orders of magnitude are required to account for the observed discharge behavior: a highly conductive layer and/or channel network controlling the fast and flashy spring responses to recharge events, as opposed to less conductive sediment accumulations sustaining the long-term base flow. The results show that the hydraulic behavior of this relict rock glacier and likely that of others can be adequately represented by two aquifer components. However, the attempt to characterize the two components by inverse modeling results in ambiguity of internal structures when solely discharge data are available.

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Subsurface lateral preferential flow network revealed by time‐lapse ground‐penetrating radar in a hillslope

Guo

Chen

Lin

2014

Water Resources Research

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Subsurface lateral preferential flow (LPF) has been observed to contribute substantially to hillslope and catchment runoff. However, the complex nature of LPF and the lack of an appropriate investigation method have hindered direct LPF observation in the field. Thus, the initiation, persistence, and dynamics of LPF networks remain poorly understood. This study explored the application of time-lapse ground-penetrating radar (GPR) together with an artificial infiltration to shed light on the nature of LPF and its dynamics in a hillslope. Based on our enhanced field experimental setup and carefully refined GPR data postprocessing algorithms, we developed a new protocol to reconstruct LPF networks with centimeter resolution. This is the first time that a detailed LPF network and its dynamics have been revealed noninvasively along a hillslope. Real-time soil water monitoring and field soil investigation confirmed the locations of LPF mapped by time-lapse GPR surveys. Our results indicated the following: (1) Increased spatial variations of radar signals after infiltration suggested heterogeneous soil water changes within the studied soil, which reflected the generation and dynamics of LPF; (2) Two types of LPF networks were identified, the network at the location of soil permeability contrasts and that formed via a series of connected preferential flow paths; and (3) The formation and distribution of LPF networks were influenced by antecedent soil water condition. Overall, this study demonstrates clearly that carefully designed time-lapse GPR surveys with enhanced data postprocessing offer a practical and nondestructive way of mapping LPF networks in the field, thereby providing a potentially significant enhancement in our ability to study complex subsurface flow processes across the landscape.

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Hillslope threshold response to rainfall: (1) A field based forensic approach

Cited by 171 publications

References 38 publications

Form and function in hillslope hydrology: characterization of subsurface flow based on response observations

Form and function in hillslope hydrology: characterization of subsurface flow based on response observations

Investigating groundwater flow components in an Alpine relict rock glacier (Austria) using a numerical model

Subsurface lateral preferential flow network revealed by time‐lapse ground‐penetrating radar in a hillslope

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