River Engineering for Highway Encroachments FHWA HDS-6

Richardson, E. V.; Lagasse, Peter F.

doi:10.1061/41147(392)109

Cited by 28 publications

(35 citation statements)

References 19 publications

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“…A consistent finding of all experimental studies on falling apron development reviewed (Central Board of Irrigation, 1939;Skrebkov et al, 1991;Thiel, 2002;Van der Hoeven, 2002) is that the cover layer that forms on an eroding slope is only a single rock particle thick. This notion is in contrast to most riprap design schemes that require filters beneath the rock covers to prevent underlying fine soils from moving through the protective layer.…”

Section: Discussionmentioning

confidence: 66%

“…calculated water velocities and depths, and the shear stresses that they produce on stream channel beds and banks) and the channel scour depths that result, the consequences of failure, and the cost of overdesigning the apron to achieve the desired factor of safety. Skrebkov et al (1991) suggest that f s ¼ 1.5 at a minimum. We propose that the safety factors recommended by the USACE (Biedenharn et al, 1997, page A-32;and USACE, 1994, pages 3-11), which are presented in Table I, be used.…”

Section: Apron Volume Safety Factormentioning

confidence: 95%

“…Ideas on which the model is based were drawn primarily from the concise narratives of falling apron processes observed during scale-model experiments carried out at the CWPRS (Central Board of Irrigation, 1939, pages 92-108), along with the accompanying sketches, which are similarly clear and informative. Additional intuitive understanding of apron launching was provided by the experimental findings of Van der Hoeven (2002) and Thiel (2002), which are summarized by Verhagen et al (2003), and by those of Skrebkov et al (1991).…”

Section: Kinematic Model Of Falling Apron Behaviourmentioning

confidence: 96%

“…Based on experimental laboratory studies, Skrebkov et al (1991) found that when stones from the apron are undermined, they begin to slide down the bank, wobbling and turning as they move, but they do not roll. They note that the protected banks form with a 2:1 slope with a more or less continuous rock cover along the bank that gradually moves from the end of the falling apron towards the toe of the slope.…”

Section: Experimental Studiesmentioning

confidence: 98%

“…Brown and Clyde, 1989; U.S. Army Corps of Engineers (USACE), 1994; Przedwojski et al, 1995;Biedenharn et al, 1997;Garg, 2002;Richardson et al, 2001;Schiereck, 2001;CIRIA, CUR, CETMEF, 2007] scarcely differs from the general principles presented by Bell (1890) and Spring (1903), and applied by Gales (1920Gales ( , 1938. Quantities of stone needed to provide adequate protective covers on eroding banks are calculated based on a volume conservation principal that implies at best an unclear understanding of the physical processes that take place after stone is launched and moves down a slope.…”

Section: Introductionmentioning

confidence: 97%

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River bank stabilization using rock riprap falling aprons

Froehlich¹

2008

River Research & Apps

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A rational mathematical model is presented that provides a sensible and realistic description of the physical processes that take place as a horizontal rock riprap apron (generally known as a 'falling apron') launches in stages and then gradually covers and protects an eroding river bank. The model is a simplified kinematic description of complex riprap cover development that does not reference directly the forces that lead to stream bank erosion or apron deployment. The formulation accounts for the regularly repeated processes of slope erosion followed by rock settlement that take place along a receding stream bank. Ideas used to develop the model are based on published results of small-scale experiments of falling apron behaviour, and on experience that has influenced current design practices. The model is uncomplicated and can be applied without difficulty to evaluate the adequacy of apron thickness, the amount of stone lost during deployment, the effect of rock riprap properties, and the lateral extent of bank erosion before complete slope coverage is established. However, application is limited to river reaches that are not highly curved.

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Section: Discussionmentioning

confidence: 66%

Section: Apron Volume Safety Factormentioning

confidence: 95%

Section: Kinematic Model Of Falling Apron Behaviourmentioning

confidence: 96%

Section: Experimental Studiesmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 97%

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River bank stabilization using rock riprap falling aprons

Froehlich¹

2008

River Research & Apps

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Impacts of river bank stabilization using riprap on fish habitat in two contrasting environments

Massey

Biron

Choné

2016

Earth Surf Processes Landf

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Riverbank stabilization using rock riprap is commonly used for protecting road and bridge structures from fluvial erosion. However, little is known about how streams adjust to such perturbation or how this can affect fish habitat in different fluvial environments, particularly for non-salmonid species in small streams. The objective of this study is to assess impacts of riprap on fish habitat quantity and quality through a pairwise comparison of 27 stabilized and non-stabilized stream reaches in two physiographic regions, the Saint Lawrence Lowlands and the Appalachian highlands of Montérégie-Est (Quebec, Canada). Both quantitative (Hydro-morphological Index of Diversity, HMID) and qualitative (Qualitative Habitat Evaluation Index, QHEI) fish habitat assessment techniques are applied in order to compare results between methods. For each stream reach depth and velocity were measured to calculate HMID. In-stream cover (woody debris, overhanging vegetation, undercut banks, aquatic macrophytes) and habitat units (pools, riffles, runs, glides) were also documented and used to determine QHEI. Results show that overall bank stabilization using riprap at bridge and stream crossings alters fish habitat characteristics. Loss of in-stream covers and riparian vegetation lower QHEI scores at stabilized reaches, especially in more pristine Appalachian streams, but has less impact on already altered straightened Lowlands streams. In this latter context, some positive alterations of fish habitat were observed in riprapped reaches due to the coarsening of the substrate and an induced increase of slope. The two metrics (HMID and QHEI) revealed similar differences between stabilized and non-stabilized sites for Lowlands sites, but their level of agreement was much less in the Appalachian streams, suggesting caution when interpreting habitat quality results based on a single metric.

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Water level induced changes of habitat quality determine fish community composition in restored and modified riverbanks of a large alpine river

Pander

Nagel

Ingermann

et al. 2021

Internat Rev Hydrobiol

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Bank habitats provide important functions for riverine fish. Yet, they have been heavily modified by land use, technical flood protection measures, and hydropower installations. Fish species requiring specific habitats to complete their life cycle have strongly declined and therefore become target species of river restoration measures.This study compared abiotic conditions and fish community composition of three bank habitat types in a large alpine river, comprising different degrees of alteration compared to the natural state (concrete profile, bank riprap, and naturally restored riverbank). Significant differences in abiotic habitat characteristics such as bed material, water depth, turbidity, submerged vegetation, and temperature were detected between the three bank habitat types and sampling seasons. These water leveldependent structural changes had the strongest effect on fish community composition as detected by distance-based linear modeling. Small specimens between 3 and 13 cm TL and juveniles were most abundant in the restored areas, except for Lota lota, which was most abundant in the man-made bank riprap. Target species of conservation were mostly detected in restored areas, particularly the critical young life stages of Chondrostoma nasus, Barbus barbus, and Thymallus thymallus. Water level strongly determined accessibility and suitability of bank habitats, with shallow, gravel-dominated habitats comprising flat bank angles being most beneficial for these species. The findings of this study provide evidence for the success of bank habitat restoration in structurally impacted alpine rivers on target species of conservation. Fluctuating water levels and discharges typical for alpine rivers should be better considered in restoration planning, particularly in light of climate change, affecting the timing and amplitude of discharge in these systems.

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River Engineering for Highway Encroachments FHWA HDS-6

Cited by 28 publications

References 19 publications

River bank stabilization using rock riprap falling aprons

River bank stabilization using rock riprap falling aprons

Impacts of river bank stabilization using riprap on fish habitat in two contrasting environments

Water level induced changes of habitat quality determine fish community composition in restored and modified riverbanks of a large alpine river

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