Scaling relationships and evolution of distributary networks on wave‐influenced deltas

Jerolmack, D. J.; Swenson, John B.

doi:10.1029/2007gl031823

Cited by 151 publications

(200 citation statements)

References 30 publications

Supporting

Mentioning

190

Contrasting

Order By: Relevance

“…The fact that T s is much larger than these fluctuations and is associated with T ch , which characterizes an ''avulsion'' time scale, supports the idea of additional surface instabilities [Jerolmack and Swenson, 2007]. For example, on relatively short time scales in-channel instabilities force flow spreading and the formation of multiple bifurcation-based channels [Edmonds and Slingerland, 2007], and on longer time scales (e.g., T ch , T s ) another instability arises from differential topography, causing larger-scale shifts in the flow [Jerolmack and Mohrig, 2007;Jerolmack and Swenson, 2007]. The implication for distributary lobes in DB07 is that the site of lobe evolution may be established by fan topography, whereas the details of lobe growth are accomplished by a subset network of bifurcation channels that stem from a parent channel.…”

Section: Implication Of T S For Shoreline Dynamicssupporting

confidence: 49%

Influence of steady base‐level rise on channel mobility, shoreline migration, and scaling properties of a cohesive experimental delta

Martin¹,

Sheets²,

Paola³

et al. 2009

J. Geophys. Res.

View full text Add to dashboard Cite

[1] Here we describe results from an alluvial delta physical experiment with and without steady base-level rise. Using a unique cohesive sediment mixture that promotes the development of persistent channels and a rugose shoreline, we quantitatively characterize channel network properties as a function of base-level rise in a distributary system that reproduces many aspects of the geometry of natural deltas. Analysis of the experimental data shows clear dynamical differences between the predominantly progadational and aggradational phases of the experiment. The experiment was conducted in two phases: a first in which the delta prograded into standing water of constant depth in the absence of base-level rise and a second during which steady base-level rise was imposed on the system, forcing a twofold increase in topset aggradation due to greater sediment retention in the fluvial reach. The shift in sediment mass balance to enhanced fluvial deposition in the second phase caused channel network mobility to increase, reducing the autogenic channel time scale from 23.5 to 12.5 h and supporting a positive correlation between deposition and channel avulsion frequency. An independent shoreline time scale that characterizes the dominant time over which shoreline regression is persistent closely correlates with measurements of the channel network (28.3 h during fan progradation and 9.5 h during fan aggradation). These metrics suggest a strong coupling between channel network and shoreline kinematics and a more active fluvial surface during fan aggradation by a factor of 2 to 3, similar to the increase in aggradation rate. Spatial scaling of shoreline roughness reveals that maximum shoreline variability is set by the scale of distributary lobes. Strong coupling exists between delta growth and shoreline geometry during progradation. During aggradation, however, shoreline variability is not solely due to distributary lobe growth but is also set by shoreline transgression over inactive portions of the delta, illustrating a decoupling between fan kinematics and fan geometry. This decoupling, together with the matched increase in channel network mobility and fluvial aggradation, suggest the stratigraphic architecture may not be a strong geometric signal of different fluvial surface conditions either.Citation: Martin, J., B. Sheets, C. Paola, and D. Hoyal (2009), Influence of steady base-level rise on channel mobility, shoreline migration, and scaling properties of a cohesive experimental delta,

show abstract

Section: Implication Of T S For Shoreline Dynamicssupporting

confidence: 49%

Influence of steady base‐level rise on channel mobility, shoreline migration, and scaling properties of a cohesive experimental delta

Martin¹,

Sheets²,

Paola³

et al. 2009

J. Geophys. Res.

View full text Add to dashboard Cite

show abstract

“…For the deltas we studied, static box counting of shoreline snapshots gives D = 1.03 ± 0.04, suggesting that shorelines of growing deltas are not fractal (since mathematically D > 1 corresponds to an "infinitely rough" fractal curve, while D = 1 corresponds to a "smooth" curve with only finite roughness [Mandelbrot, 1967;Turcotte, 1997]). Combined with previous observations on the non-fractality of beach coasts [Murray and Barton, 2007], where wave-driven alongshore transport is a significant process [Jerolmack and Swenson, 2007], this suggests that constructional coasts made of mobile sediment may be generally nonfractal. We note that allometric growth and a fractal boundary are conceptually distinct, i.e., isometric growth of a fractal curve should be possible in principle (although if measured with a fixed ruler size, isotropic expansion of a fractal would still yield allometric length-area scaling).…”

Section: Land Growthmentioning

confidence: 80%

“…In degrading deltas, enhanced compaction in organic-rich overbank areas [Törnqvist et al, 2008] may result in more fractal shorelines as non-channel areas subside below sea level, while in wave-dominated deltas diffusive dampening of the channelbifurcation instability [Jerolmack and Swenson, 2007] could result in non-fractal channel patterns.…”

Section: Discussionmentioning

confidence: 99%

Delta allometry: Growth laws for river deltas

Wolinsky¹,

Edmonds

Martin³

et al. 2010

Geophysical Research Letters

View full text Add to dashboard Cite

[1] Under projected scenarios of sea-level rise, subsidence, and sediment starvation many deltas around the world are expected to drown. Delta growth dynamics, which determine the ability of a delta to adapt to these changes, are poorly understood due to the difficulty of measuring change in slowly evolving landscapes. We use timeseries imagery of experimental, numerical, and field-scale deltas to derive four laws that govern the growth of riverdominated deltas. Land area grows at a constant rate in the absence of relative sea level change, while wetted area keeps pace, maintaining a constant wetted fraction over the delta surface. Scaling of edge-lengths versus areas suggests delta shorelines are nonfractal, even though the channel network is fractal. Consequently channel-edge length, which provides critical habitat, grows more rapidly than delta area. These laws provide a blueprint for delta growth that will aid in delta restoration and help predict how existing deltas will evolve. Citation: Wolinsky, M.

show abstract

“…Studies based on the relationship between the distributary network of wave-influenced deltas showed that wave energy controls the network topology by suppressing mouth-bar development, thereby preferentially eliminating smaller-scale distributaries [Jerolmack and Swenson, 2007].…”

Section: Introductionmentioning

confidence: 99%

The effect of wind waves on the development of river mouth bars

Nardin

Fagherazzi

2012

Geophysical Research Letters

View full text Add to dashboard Cite

[1] River deltas are among the most important environments on earth, housing productive ecosystems and a large fraction of the human population. The key process for delta development is the deposition of mouth bars in front of delta distributaries. Predicting mouth bar formation on marine coastlines is complex because of the interactions between waves, tides, water and sediment discharge. Here we study the effects of waves on mouth bar growth with the coupled sediment transport and wave model Delft3D-SWAN. Our results show that wave characteristics (height, period, and direction) play an important role in the formation of mouth bars. In our numerical experiments waves affect bar development in three ways: by modifying the direction of the river jet, by increasing bottom shear stresses at the river mouth, and by changing bottom friction and hence increasing jet spreading. We further show that high waves with long period prevent the formation of mouth bars; in particular, wave angles between 45 and 60 are the least favorable to bar formation, likely producing a deflected river mouth.

show abstract

Scaling relationships and evolution of distributary networks on wave‐influenced deltas

Cited by 151 publications

References 30 publications

Influence of steady base‐level rise on channel mobility, shoreline migration, and scaling properties of a cohesive experimental delta

Influence of steady base‐level rise on channel mobility, shoreline migration, and scaling properties of a cohesive experimental delta

Delta allometry: Growth laws for river deltas

The effect of wind waves on the development of river mouth bars

Contact Info

Product

Resources

About