The Salt Marshes of the Dovey Estuary

Yapp, R. H.; Johns, D M; Jones, Owen

doi:10.2307/2255448

Cited by 55 publications

(29 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Further tidal channel development occurs as headward erosion and elongation caused by tidal energy (Knighton, 1992;Shi et al, 1995). A less prominent model is that vegetation colonization of the tideflats occurs first and produces hummocks that direct and concentrate ebb tide flow; as the marsh aggrades the incipient channels deepen (Yapp et al, 1917). Recently, two additional models of tidal channel development have been suggested.…”

Section: Discussionmentioning

confidence: 99%

A conceptual model of depositional, rather than erosional, tidal channel development in the rapidly prograding Skagit River Delta (Washington, USA)

Hood

2006

Earth Surf Processes Landf

View full text Add to dashboard Cite

The origin and growth of blind tidal channels is generally considered to be an erosional process. This paper describes a contrasting depositional model for blind tidal channel origin and development in the Skagit River delta, Washington, USA. Chronological sequences of historical maps and photos spanning the last century show that as sediments accumulated at the river mouth, vegetation colonization created marsh islands that splintered the river into distributaries. The marsh islands coalesced when intervening distributary channels gradually narrowed and finally closed at the upstream end to form a blind tidal channel, or at mid-length to form two blind tidal channels. Channel closure was probably often mediated through gradient reduction associated with marsh progradation and channel lengthening, coupled with large woody debris blockages. Blind tidal channel evolution from distributaries was common in the Skagit marshes from 1889 to the present, and it can account for the origin of very small modern blind tidal channels. The smallest observed distributary-derived modern blind tidal channels have mean widths of 0·3 m, at the resolution limit of the modern orthophotographs. While channel initiation and persistence are similar processes in erosional systems, they are different processes in this depositional model. Once a channel is obstructed and isolated from distributary flow, only tidal flow remains and channel persistence becomes a function of tidal prism and tidal or wind/wave erosion. In rapidly prograding systems like the Skagit, blind tidal channel networks are probably inherited from the antecedent distributary network. Examination of large-scale channel network geometry of such systems should therefore consider distributaries and blind tidal channels part of a common channel network and not entirely distinct elements of the system. Finally, managers of tidal habitat restoration projects generally assume an erosional model of tidal channel development. However, under circumstances conducive to progradation, depositional channel development may prevail instead.

show abstract

Section: Discussionmentioning

confidence: 99%

A conceptual model of depositional, rather than erosional, tidal channel development in the rapidly prograding Skagit River Delta (Washington, USA)

Hood

2006

Earth Surf Processes Landf

View full text Add to dashboard Cite

show abstract

“…A large body of literature exists describing salt marsh channel initiation and development [e.g., Yapp et al , 1916, 1917; Pestrong , 1965; Redfield , 1965, 1972; Beeftink , 1966; Gardner and Bohn , 1980; French and Stoddart , 1992; Steel and Pye , 1997], the hydrodynamics of salt marsh channels [e.g., Boon , 1975; Pethick , 1980; French and Stoddart , 1992; Rinaldo et al , 1999a, 1999b; Temmerman et al , 2005b; Fagherazzi et al , 2008], and their morphometric features [e.g., Fagherazzi et al , 1999; Rinaldo et al , 1999a, 1999b; Marani et al , 2003; Novakowski et al , 2004; Feola et al , 2005; Marani et al , 2006]. In spite of their fundamental role in the ecomorphodynamic evolution of salt marsh systems, only in the last few years have numerical models been developed to describe the morphogenesis and long‐term dynamics of salt marsh channels [e.g., Fagherazzi and Furbish , 2001; Fagherazzi and Sun , 2004; D'Alpaos et al , 2005, 2006; Marciano et al , 2005; Perillo et al , 2005; Minkoff et al , 2006; Kirwan and Murray , 2007; Temmerman et al , 2007].…”

Section: Dynamics Of Marsh Channelsmentioning

confidence: 99%

Numerical models of salt marsh evolution: Ecological, geomorphic, and climatic factors

Fagherazzi¹,

Kirwan²,

Mudd³

et al. 2012

Reviews of Geophysics

589

450

View full text Add to dashboard Cite

[1] Salt marshes are delicate landforms at the boundary between the sea and land. These ecosystems support a diverse biota that modifies the erosive characteristics of the substrate and mediates sediment transport processes. Here we present a broad overview of recent numerical models that quantify the formation and evolution of salt marshes under different physical and ecological drivers. In particular, we focus on the coupling between geomorphological and ecological processes and on how these feedbacks are included in predictive models of landform evolution. We describe in detail models that simulate fluxes of water, organic matter, and sediments in salt marshes. The interplay between biological and morphological processes often produces a distinct scarp between salt marshes and tidal flats. Numerical models can capture the dynamics of this boundary and the progradation or regression of the marsh in time. Tidal channels are also key features of the marsh landscape, flooding and draining the marsh platform and providing a source of sediments and nutrients to the marsh ecosystem. In recent years, several numerical models have been developed to describe the morphogenesis and long-term dynamics of salt marsh channels. Finally, salt marshes are highly sensitive to the effects of long-term climatic change. We therefore discuss in detail how numerical models have been used to determine salt marsh survival under different scenarios of sea level rise.

show abstract

“…The cyclic marsh dynamics may not always be apparent, as marshes may appear to be static due to the long time scales involved (decades to centuries). Although these cyclic dynamics have been recognised for a long time (Yapp et al ; Gray ; Allen ), our understanding of the actual processes driving these dynamics remains poor. Existing studies on cyclic marsh loss by lateral erosion and marsh expansion by re‐establishment of pioneer vegetation mainly use conceptual modeling (van de Koppel et al ; Mariotti and Fagherazzi ; Tambroni and Seminara ) or large‐scale empirical approaches, by relating remote sensing data of salt marsh retreat/expansion to datasets of hydro‐meteorological forcing (Pye ; Cox et al ; Van der Wal and Pye ; Van der Wal et al ; Wang and Temmerman ).…”

Section: Introductionmentioning

confidence: 99%

Short-term mudflat dynamics drive long-term cyclic salt marsh dynamics

et al. 2016

View full text Add to dashboard Cite

Our study aims to enhance process understanding of the long-term (decadal and longer) cyclic marsh dynamics by identifying the mechanisms that translate large-scale physical forcing in the system into vegetation change, in particular (i) the initiation of lateral erosion on an expanding marsh, and (ii) the control of seedling establishment in front of an eroding marsh-cliff. Short-term sediment dynamics (i.e., seasonal and shorter changes in sediment elevation) at the mudflat causes variation in mudflat elevation over time (dz TF ). The resulting difference in elevation between the tidal flat and adjacent marsh (DZ) initiates lateral marsh erosion. Marsh erosion rate was found to depend on sediment type and to increase with increasing DZ and hydrodynamic exposure. Laboratory and field experiments revealed that seedling establishment was negatively impacted by an increasing dz TF . As the amplitude of dz TF increases towards the channel, expanding marshes become more prone to lateral erosion the further they extend on a tidal flat, and the chance for seedlings to establish increases with the distance that marsh has eroded back towards the land. This processbased understanding, showing the role of sediment dynamics as explanatory factor for marsh cyclicity, is important for protecting and restoring valuable marsh ecosystems. Overall, our experiments emphasize the need for understanding the connections between neighbouring ecosystems such as mudflat and salt marsh.

show abstract

The Salt Marshes of the Dovey Estuary

Cited by 55 publications

References 0 publications

A conceptual model of depositional, rather than erosional, tidal channel development in the rapidly prograding Skagit River Delta (Washington, USA)

A conceptual model of depositional, rather than erosional, tidal channel development in the rapidly prograding Skagit River Delta (Washington, USA)

Numerical models of salt marsh evolution: Ecological, geomorphic, and climatic factors

Short-term mudflat dynamics drive long-term cyclic salt marsh dynamics

Contact Info

Product

Resources

About