A threshold condition for soil‐water transport

Torres, Raymond

doi:10.1002/hyp.5060

Cited by 26 publications

(25 citation statements)

References 29 publications

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“…Sidle et al (1995) showed that hollows or zero-order basins, which produced little or no runoff during dry conditions, contributed significantly to total catchment runoff once an antecedent moisture threshold was reached. These findings were consistent with later observations by Torres (2002), who speculated on the presence of a threshold value in the relationship between soil moisture and pressure head, above which rapid pressure head reactions occurred in the unsaturated zone, leading to quick soil-water redistribution and fast discharge responses. Furthermore, in two recent papers Detty and McGuire (2010a, b) identified a clear threshold relationship between the sum of antecedent wetness and gross precipitation and storm runoff: below the threshold total runoff was minimal whereas above it total runoff was linearly correlated with the combination of antecedent soil moisture and rainfall.…”

Section: Introductionsupporting

confidence: 93%

The influence of soil moisture on threshold runoff generation processes in an alpine headwater catchment

Penna

Meerveld

Gobbi

et al. 2011

Hydrol. Earth Syst. Sci.

378

303

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Abstract. This study investigates the role of soil moisture on the threshold runoff response in a small headwater catchment in the Italian Alps that is characterised by steep hillslopes and a distinct riparian zone. This study focuses on: (i) the threshold soil moisture-runoff relationship and the influence of catchment topography on this relation; (ii) the temporal dynamics of soil moisture, streamflow and groundwater that characterize the catchment's response to rainfall during dry and wet periods; and (iii) the combined effect of antecedent wetness conditions and rainfall amount on hillslope and riparian runoff. Our results highlight the strong control exerted by soil moisture on runoff in this catchment: a sharp threshold exists in the relationship between soil water content and runoff coefficient, streamflow, and hillslope-averaged depth to water table. Low runoff ratios were likely related to the response of the riparian zone, which was almost always close to saturation. High runoff ratios occurred during wet antecedent conditions, when the soil moisture threshold was exceeded. In these cases, subsurface flow was activated on hillslopes, which became a major contributor to runoff. Antecedent wetness conditions also controlled the catchment's response time: during dry periods, streamflow reacted and peaked prior to hillslope soil moisture whereas during wet conditions the opposite occurred. This difference resulted in a hysteretic behaviour in the soil moisture-streamflow relationship. Finally, the influence of antecedent moisture conditions on runoff was also evident in the relation between cumulative rainfall and total stormflow. Small storms during dry conditions produced low stormflow amounts, likely mainly from overland flow from the near saturated riparian zone. Conversely, for rainfall events during wet conditions, higher stormflow values were observed and hillslopes must have contributed to streamflow.

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Section: Introductionsupporting

confidence: 93%

The influence of soil moisture on threshold runoff generation processes in an alpine headwater catchment

Penna

Meerveld

Gobbi

et al. 2011

Hydrol. Earth Syst. Sci.

378

303

View full text Add to dashboard Cite

show abstract

“…How the perturbation (irrigation) was exactly transmitted through the flow domain at our site remains unclear. For example, the celerity at our site could have been produced by a pressure wave response that gave rise to rapid soil water redistribution (as per Torres, 2002). On the other hand, McGuire and McDonnell (2010) indicated that advective preferential flow transport was the most plausible mechanism for observed rapid soil moisture responses in the unsaturated zone at this study site.…”

Section: Celerities and Velocities At The Hillslope Scalementioning

confidence: 74%

A sprinkling experiment to quantify celerity–velocity differences at the hillslope scale

Verseveld

Barnard

Graham³

et al. 2017

Hydrol. Earth Syst. Sci.

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Abstract. Few studies have quantified the differences between celerity and velocity of hillslope water flow and explained the processes that control these differences. Here, we asses these differences by combining a 24-day hillslope sprinkling experiment with a spatially explicit hydrologic model analysis. We focused our work on Watershed 10 at the H. J. Andrews Experimental Forest in western Oregon. Celerities estimated from wetting front arrival times were generally much faster than average vertical velocities of δ 2 H. In the model analysis, this was consistent with an identifiable effective porosity (fraction of total porosity available for mass transfer) parameter, indicating that subsurface mixing was controlled by an immobile soil fraction, resulting in the attenuation of the δ 2 H input signal in lateral subsurface flow. In addition to the immobile soil fraction, exfiltrating deep groundwater that mixed with lateral subsurface flow captured at the experimental hillslope trench caused further reduction in the δ 2 H input signal. Finally, our results suggest that soil depth variability played a significant role in the celerityvelocity responses. Deeper upslope soils damped the δ 2 H input signal, while a shallow soil near the trench controlled the δ 2 H peak in lateral subsurface flow response. Simulated exit time and residence time distributions with our hillslope hydrologic model showed that water captured at the trench did not represent the entire modeled hillslope domain; the exit time distribution for lateral subsurface flow captured at the trench showed more early time weighting.

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“…testing whether Equation (3) is valid for CB1 type applications). If, as suggested by Torres (2002), models like InHM are incapable of simulating hydrologic response for certain situations where the Darcy-Buckingham continuum assumptions break down, it is clear, from the effort reported here, that much better temporal resolution is needed for discharge, pressure head, and soil water content observations for conclusive data-based assessments. The temporal scale for the type of response that potentially occurred at CB1 would be on the order of minutes to a precision of, for example, millimeters for pressure head.…”

Section: Discussionmentioning

confidence: 91%

Rapid simulated hydrologic response within the variably saturated near surface

Ebel

Loague

2007

Hydrological Processes

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Column and field experiments have shown that the hydrologic response to increases in rainfall rates can be more rapid than expected from simple estimates. Physics-based hydrologic response simulation, with the Integrated Hydrology Model (InHM), is used here to investigate rapid hydrologic response, within the variably saturated near surface, to temporal variations in applied flux at the surface boundary. The factors controlling the speed of wetting front propagation are discussed within the Darcy-Buckingham conceptual framework, including kinematic wave approximations. The Coos Bay boundary-value problem is employed to examine simulated discharge, pressure head, and saturation responses to a large increase in applied surface flux. The results presented here suggest that physics-based simulations are capable of representing rapid hydrologic response within the variably saturated near surface. The new InHM simulations indicate that the temporal discretization and measurement precision needed to capture the rapid subsurface response to a spike increase in surface flux, necessary for both data-based analyses and evaluation of physics-based models, are smaller than the capabilities of the instrumentation deployed at the Coos Bay experimental catchment.

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A threshold condition for soil‐water transport

Cited by 26 publications

References 29 publications

The influence of soil moisture on threshold runoff generation processes in an alpine headwater catchment

The influence of soil moisture on threshold runoff generation processes in an alpine headwater catchment

A sprinkling experiment to quantify celerity–velocity differences at the hillslope scale

Rapid simulated hydrologic response within the variably saturated near surface

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