Shelf sand supply determined by glacial-age sea-level modes, submerged coastlines and wave climate

Abstract

Submerged paloeshorelines preserved on the continental shelf indicate the depths of the most frequent (modal) low sea-levels within the glacial stages of the Late Quaternary. Here we have determined the south-east Australian shelf configuration when sea level was 40 m and 60 m below present-day sealevel (depths of the most persistent paleoshorelines within the last 120 ka), and we resolve the wave climate variations influencing the sediment transport pathways over this period. We present evidence demonstrating that the combination of shelf morphological evolution, changes in sea-level and variations in wave climate is responsible for latitudinal changes in sediment transport and deposition during the interglacial states. the paleoshoreline and shelf evolution is key to understanding the distribution of present-day shelf sand deposits and the contemporary sand budget response to future wave climate changes.wave climate throughout the glacial cycle, to resolve the connectivity and longshore sediment transport paths during the Late Quaternary glacial and interglacial cycles. The definition of paleo-sediment transport and relict sand bodies is essential data to apply to the projection of modern coastline response to net changes in wave climate, sediment transport and sea levels over the coming century. Scientific RepoRtS | (2020) 10:462 | https://doi.Figure 7. Conceptual model showing the shelf sand deposits evolution with changes in sea-level over shallow (a) and steep (b) slope gradients (oblique wave energy is assumed for both scenarios).Scientific RepoRtS | (2020) 10:462 | https://doi.

Shoreface mesoscale morphodynamics: A review

“…Early approaches to long-term shoreface evolution assumed time-invariant shoreface profiles (Cowell et al, 1999), while later models allowed for shoreface profile evolution according to the presence of an erodible or non-erodible substrate (Thieler et al, 1995). Some of the most recent studies point to the importance of the slope as a strong control for long term evolution (Ciarletta et al, 2019;Deng and Wu, 2020;Ribó et al, 2020).…”

Transitional wave climate regions on continental and polar coasts in a warming world

“…This classi cation was repeated for the RCP2.6 and RCP8.5 scenarios (2075-2099) using the calculated centroids from the historical conditions rather than generating new ones. Here, we will focus on the RCP8.5 scenario but more details of the RCP2.6 scenario can be found in the supplementary information 14,16,(19)(20)(21)(22)(23).…”

“…Wave climate is well known to be a primary driver of coastal risk (erosion 1,3 and ooding 16,17 ), and controls the balance of mass and energy uxes in coastal ecosystems 18 . From a global perspective, characteristics of coastal environments, such as the distribution of ecosystems (coral reefs 19 , seagrasses 20 , and mangroves 21 ) and coastal features (carbonsoil mangroves 22 , sedimentary environments 23 ), vary based on the major climate regions (planetary areas delimited by atmospheric circulation and similar climate conditions) that they inhabit. Indeed, not only changes in storminess but also spatial and temporal changes in climate regions (e.g., tropicalsubtropical, subtropical-extratropical, and extratropical-polar), can severely alter nearshore processes and cause substantial changes to the prevailing wave climate (e.g., signi cant wave height, mean wave direction).…”

Climate-induced variability in South Atlantic wave direction over the past three millennia

“…Few studies have investigated paleo variability in wave climate 12 – 15 , largely because near-instantaneous signals such as wave height and period are difficult to derive from geological record. However, such archives may document changes in the long-term mean directional wave energy flux (EF θ ), which represents the rate of total energy transported in an orthogonal direction to the wave-crest propagation over a period of time.…”