Overwash processes along a gravel beach in south‐east Ireland

Carter, R. W. G.; Orford, Julian D.

doi:10.1002/esp.3290060503

Cited by 35 publications

(11 citation statements)

References 8 publications

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“…is small. Sediment is deposited on the dune crest or in the throat of an existing washover (CARTER and ORFORD, 1981;FISHER, LEATHERMAN, and PERRY, 1974;LEATHERMAN, 1976a;ORFORD, JENNINGS, and PETHICK, 2003) and hence the crest ofthe throat or herm is raised, which may eventually halt further overwash. The term crest accumulation was first used to define overwash processes by ORFORD, JENNINGS, and PKTHICK (2003).…”

Section: Runup Overwashmentioning

confidence: 97%

“…Current proflle change models have only been calibrated and tested for sandy beacbes. Overwasb is also an important process on gravel and sbingle barriers {e.g., BRADBURY and POWKI.L, 1992;CARTER and ORFORD, 1981), and although understanding of overwash processes has been advanced as a result of studies on such barriers, tbere remains scope to develop profile change models for coarse sediment beaches.…”

Section: Future Model Developmentmentioning

confidence: 99%

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State of Knowledge on Measurement and Modeling of Coastal Overwash

Donnelly¹,

Kraus²,

Larson³

2006

Journal of Coastal Research

224

192

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N., and LARSON, M. 2006. State of knowledge on measurement and modeling of coastal ovorwash. Journal of Coastal Research, 22(41,, ISSN 0749-0208.A critical review is presented on the state of knowledge and calculation capability for coastal overwash. Overwash and overwash deposits Iwashover) accompanying hurricanes and severe storms can devastate coastal communities and habitat, hut in many areas tbese processes are essential for maintaining the integiity of harrier islands while creating new hahitat. This review covers general studies of overwash processes, studies from a geological perspective, physical modeling, field studies including measurements of wa.'ihovers and related hydraulics, and the state of numerical modeling capahility to predict overwash. Although significant literature exists describing individual overwasb events and locations experiencing frequent overwash, complete bydrodynamic and morphologic documentation of an overwasb event is lacking. A limited numher of algorithms or models exist to quantify overwash occurrence, deposited sand volume, and upper beacb profile evolution. Existing models of overwash occurrence and one-dimensional heacb profile evolution bave heen shown to perform successfully against availahle data, and areas of improvement are identified. Models must be made capable of simulating the various wasbover morpbologies that have been pn)duced by different hydrodynamics, overwash spreading hased on dune topography, friction and percolation, and interaction between swasb bores. Comprebensive laboratory and field data sets to acbieve these aims are still lacking.

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Section: Runup Overwashmentioning

confidence: 97%

Section: Future Model Developmentmentioning

confidence: 99%

State of Knowledge on Measurement and Modeling of Coastal Overwash

Donnelly¹,

Kraus²,

Larson³

2006

Journal of Coastal Research

224

192

View full text Add to dashboard Cite

show abstract

“…The presence of the upfan-sloping foresets of facies F in a position more landward of the facies E beachface deposits indicates that these foresets accumulated during storm-generated surges that overtopped the beach berm and prograded into a back-beach low (e.g. Carter & Orford, 1981;Orford & Carter, 1982;Blair, 1999). The 30±35°dip on some of these facies F foresets (Fig.…”

Section: Reconstructed Sedimentary Processesmentioning

confidence: 99%

Sedimentology of the debris‐flow‐dominated Warm Spring Canyon alluvial fan, Death Valley, California

Blair¹

1999

Sedimentology

150

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Facies analysis of widely distributed exposures of the 32á6 km 2 and 8á1-kmlong Warm Spring Canyon fan, central Death Valley, shows that it has been built principally by debris-¯ow deposits. These deposits were derived from a mature Panamint Range catchment mostly underlain by Precambrian mudrock, quartzite and dolomite. Stacked, clast-rich and matrix-supported debris-¯ow lobes of slightly bouldery, muddy, pebble±cobble gravel in beds 20±150 cm thick dominate the fan from apex to toe, accounting for 75±98% of most exposures. Interstrati®ed with the debris¯ows are less abundant (2±25% of cuts), thinner (5±30 cm) and more discontinuous beds of clast-supported and imbricated, pebble±cobble gravel deposited by overland¯ows and gully¯ows. This facies formed by the sur®cial ®ne-fraction water winnowing of the debris ows primarily during recessional¯ood stage of the debris-¯ow events. Two other facies associations make up a small part of the fan. The incised-channel tract consists of a 250-m-wide clast-supported ribbon of irregularly to thickly bedded, boulder, pebble, cobble gravel nested within debris-¯ow deposits. This channel ®ll is oriented generally perpendicular to the Panamint range front. It formed by extensive erosion and winnowing of debris¯ows deposited within the incised channel, into which all water discharge from the catchment is funnelled. The limited presence of this facies only straddling the present incised channel indicates that this channel overall has maintained a consistent position on the fan except for slight lateral shifts, some caused by strike-slip offset. Fault offset temporarily closed the upper incised channel, causing recessional debris-¯ow mud to be ponded behind the dam. The other local facies assemblage consists of subrounded to rounded, moderately sorted pebble gravel in low-angle cross-beds that slope both basinwards and fanwards. This gravel was deposited in beachface, backshore and shoreface barrier-spit environments that developed where Lake Manly impinged on the Warm Spring fan during late Pleistocene time. These deposits straddle headcuts into, and were derived from, erosion of the debris-¯ow deposits. Wave energy sorted ®ner sediment from the shore zone, concentrated coarser sediment and rounded the coarse to very coarse pebble fraction by selective reworking.

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“…Dissipative forces, including infiltration, cause the deposition of locally derived sediment (eroded from dune front, beach and nearshore) on the crest or directly behind it. In coarse-grained barriers, sediment may even be deposited in an incipient or reactivated throat, creating a temporary plug before a further rise in water level allows larger waves to erode it (Carter and Orford, 1981). Sediment deposited on the backside of higher ridges may be redistributed by avalanching, particularly where backbarrier water levels are high .…”

Section: Overwash Regimementioning

confidence: 99%

“…Here, velocities exceed 2 m s -1 , a function of the steep water gradient between the sea and the flooded lows together with the strong flow constriction (e.g., Suter et al, 1982). Swash reflection from the dunes next to a gap also contributes to accelerated flow, and to turbulence that results in further deepening of the throat (Carter and Orford, 1981). Friction and percolation on the backside of throats are instrumental in the deposition of washover fans by sediment-laden water that is no longer constrained.…”

Section: Overwash Regimementioning

confidence: 99%