Runoff Generation, Overland Flow and Erosion on Hillslopes

Wainwright, John; Bracken, Louise

doi:10.1002/9780470710777.ch11

Cited by 14 publications

(7 citation statements)

References 216 publications

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“…Runoff processes can change dramatically the allocation of water resources, supplying plants with water from remote areas [Kirkby and Chorley, 1967;Descroix et al, 2007;Lehmann et al, 2007;Thompson et al, 2010aThompson et al, , 2010b. Hortonian (infiltration excess) runoff is one of the major runoff-generation mechanisms in these environments [Lange and Leibundgut, 2003;Wainwright and Bracken, 2011], especially under short but intensive rainfall events. Infiltration and overland flow, as the two major components of the hydrological response, are dynamically coupled in space and time, as well as shaped by both rainfall and surface characteristics.…”

Section: Introductionmentioning

confidence: 99%

The role of soil-surface sealing, microtopography, and vegetation patches in rainfall-runoff processes in semiarid areas

et al. 2013

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[1] The hydrological response of semiarid watersheds to short but intense rainfall events is complex due to feedbacks among water fluxes, vegetation patches, topography, and soil properties. This paper seeks to quantify the combined impact of soil-surface sealing, microtopography, and vegetation patches on surface hydrologic processes on a semiarid hillslope. A modeling approach using a two-layer conceptual infiltration model and twodimensional surface runoff model was developed to study rainfall-runoff relationships. This combined model is applicable to heterogeneous areas with spatially varying soil properties, landscape, and land-cover characteristics. Data from a semiarid site in southern Israel was used to evaluate the model and analyze fundamental hydrologic mechanisms. Our results indicate that seal layer, microtopography, and vegetation play important roles in dry land runoff processes: seal layer controls runoff generation; vegetation patches affect overland flow by enhancing local infiltration rates; microtopography has a small impact on the total amount of runoff, but shapes the spatial pattern of overland flow. The presence of vegetation patches amplifies the effect of microtopography by increasing spatial variability of infiltration and runoff. Results also show that water resource allocation favors vegetation patches through surface runoff, with maximum local cumulative infiltration one order of magnitude higher than the amount of water available from rainfall. This suggests a sophisticated system of water resource distribution in semiarid ecosystems through complex interactions among environmental factors.Citation: Chen, L., S. Sela, T. Svoray, and S. Assouline (2013), The role of soil-surface sealing, microtopography, and vegetation patches in rainfall-runoff processes in semiarid areas, Water Resour. Res., 49,[5585][5586][5587][5588][5589][5590][5591][5592][5593][5594][5595][5596][5597][5598][5599]

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Section: Introductionmentioning

confidence: 99%

The role of soil-surface sealing, microtopography, and vegetation patches in rainfall-runoff processes in semiarid areas

et al. 2013

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“…Hydrological connexions via overland and subsurface flows have become conceptualized as a function of water volume (supplied by rainfall and runon, depleted by infiltration, evaporation, transpiration and transmission losses) and rate of transfer (a function of pathway, hillslope length and flow resistance) (Bracken et al, 2013). These processes interact with flow resistance, varying as a function of flow depth, which establishes a feedback between rainfall, infiltration and flow routing which produces the nonlinearity seen in river hydrographs and scale-dependence of runoff coefficients (Wainwright and Bracken, 2011). …”

Section: Existing Conceptual Framework Of Sediment Connectivitymentioning

confidence: 99%

Sediment connectivity: a framework for understanding sediment transfer at multiple scales

Bracken

Turnbull

Wainwright

et al. 2014

Earth Surf Processes Landf

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(2015) 'Sediment connectivity : a framework for understanding sediment transfer at multiple scales.', Earth surface processes and landforms., 40 (2). pp. 177-188. Further information on publisher's website:http://dx.doi.org/10.1002/esp.3635Publisher's copyright statement: This is the accepted version of the following article: Bracken L. J., Turnbull L., Wainwright J. and Bogaart P. (2015), Sediment connectivity: a framework for understanding sediment transfer at multiple scales, Earth Surface Processes and Landforms, 40 (2): 177188, which has been published in nal form at http://dx.doi.org/10.1002/esp.3635. This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. ABSTRACTA major challenge for geomorphologists is to scale up small-magnitude processes to produce landscape form, yet existing approaches have been found to be severely limited. New ways to scale erosion and transfer of sediment are thus needed. This paper evaluates the concept of sediment connectivity as a framework for understanding processes involved in sediment transfer across multiple scales. We propose that the concept of sediment connectivity can be used to explain the connected transfer of sediment from a source to a sink in a catchment, and movement of sediment between different zones within a catchment: over hillslopes, between hillslopes and channels, and within channels. Using fluvial systems as an example we explore four scenarios of sediment-connectivity which represent end-members of behaviour from fully linked to fully unlinked hydrological and sediment connectivity. Sediment-travel distance -when combined with an entrainment parameter reflecting the frequency-magnitude response of the system -maps onto these end-members, providing a coherent conceptual model for the upscaling of erosion predictions. This conceptual model could be readily expanded to other process domains to provide a more comprehensive underpinning of landscape-evolution models. Thus, further research on the controls and dynamics of travel distances under different modes of transport is fundamental.

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“…Unlike more humid environments, the seasonal (or permanent) moisture deficit of drylands means that many river flows are ephemeral; when floods occur, they can be torrential and flashy. When surface hydrological connections between surface runoff source areas and river channels are eventually established, nonlinearities are introduced in rainfall-runoff relationships as source areas begin to contribute towards river discharge (Bracken & Croke, 2007;Smith, Bracken, & Cox, 2010;Wainwright & Bracken, 2011). When surface hydrological connections between surface runoff source areas and river channels are eventually established, nonlinearities are introduced in rainfall-runoff relationships as source areas begin to contribute towards river discharge (Bracken & Croke, 2007;Smith, Bracken, & Cox, 2010;Wainwright & Bracken, 2011).…”

Section: Introductionmentioning

confidence: 99%

“…Modelling the development of such floods is challenging because large surface runoff generating areas may be initially isolated from the channel network by downslope infiltration (Ambroise, 2004). When surface hydrological connections between surface runoff source areas and river channels are eventually established, nonlinearities are introduced in rainfall-runoff relationships as source areas begin to contribute towards river discharge (Bracken & Croke, 2007;Smith, Bracken, & Cox, 2010;Wainwright & Bracken, 2011). A number of definitions of hydrological connectivity have emerged in the literature (see Ali & Roy, 2009); however, in a general sense, hydrological connectivity can be defined as, "the passage of water from one part of the landscape to another … expected to generate some catchment runoff response" (Bracken & Croke, 2007, p. 1).…”

Section: Introductionmentioning

confidence: 99%

A new approach for measuring surface hydrological connectivity

Wolstenholme

Smith

Baird

et al. 2019

Hydrological Processes

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The development of surface hydrological connectivity is a key determinant of flood magnitude in drylands. Thresholds in runoff response may be reached when isolated runoff-generating areas connect with each other to form continuous links to river channels, enabling these areas to contribute to flood hydrographs. Such threshold behaviour explains observed nonlinearities and scale dependencies of dryland rainfall-runoff relationships and complicates attempts at flood prediction. However, field methods for measuring the propensity of a surface to transmit water downslope are lacking, and conventional techniques of infiltration measurement are often inappropriate for use on non-agricultural drylands. Here, we argue for a reconceptualization of the dryland surface runoff process, suggesting that the downslope transfer of water should be considered alongside surface infiltration; that is, there is a need for the "aggregated" measurement of infiltration and overland flow hydraulics.Surface application of a set volume of water at a standardized rate generates runoff that travels downslope; the distance it travels downslope is determined by infiltration along the flow, integration of flow paths, and flow resistance. We demonstrate the potential of such a combined measurement system coupled with structure-frommotion photogrammetry to identify surface controls on runoff generation and transfer on dryland hillslopes, with vegetation, slope, surface stone cover, and surface roughness all having a significant effect. The measurement system has been used on slopes up to 37 compared with the flat surface typically required for infiltration methods. On average, the field workflow takes~10-15 min, considerably quicker than rainfall simulation. A wider variety of surfaces can be sampled with relative ease, as the method is not restricted to stone and vegetation-free land. We argue that this aggregated measurement represents surface connectivity and dryland runoff response better than standard hydrological approaches and can be applied on a much greater variety of dryland surfaces.

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Runoff Generation, Overland Flow and Erosion on Hillslopes

Cited by 14 publications

References 216 publications

The role of soil-surface sealing, microtopography, and vegetation patches in rainfall-runoff processes in semiarid areas

The role of soil-surface sealing, microtopography, and vegetation patches in rainfall-runoff processes in semiarid areas

Sediment connectivity: a framework for understanding sediment transfer at multiple scales

A new approach for measuring surface hydrological connectivity

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