scholarly journals Detrital signals of coastal erosion and fluvial sediment supply during glacio-eustatic sea-level rise, Southern California, USA

Geology ◽  
2021 ◽  
Author(s):  
G.R. Sharman ◽  
J.A. Covault ◽  
D.F. Stockli ◽  
Z.T. Sickmann ◽  
M.A. Malkowski ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Detrital Zircon ◽  
Coastal Erosion ◽  
Southern California ◽  
Submarine Canyon ◽  
Sediment Supply ◽  
Sediment Budgets ◽  
The Face ◽  
Sea Fan

Coastal erosion, including sea-cliff retreat, represents both an important component of some sediment budgets and a significant threat to coastal communities in the face of rising sea level. Despite the importance of predicting future rates of coastal erosion, few prehistoric constraints exist on the relative importance of sediment supplied by coastal erosion versus rivers with respect to past sea-level change. We used detrital zircon U-Pb geochronology as a provenance tracer of river and deep-sea fan deposits from the Southern California Borderland (United States) to estimate relative sediment contributions from rivers and coastal erosion from late Pleistocene to present. Mixture modeling of submarine canyon and fan samples indicates that detrital zircon was dominantly (55%–86%) supplied from coastal erosion during latest Pleistocene (ca. 13 ka) sea-level rise, with lesser contributions from rivers, on the basis of unique U-Pb age modes relative to local Peninsular Ranges bedrock sources. However, sediment that was deposited when sea level was stable at its highest and lowest points since the Last Glacial Maximum was dominantly supplied by rivers, suggesting decreased coastal erosion during periods of sea-level stability. We find that relative sediment supply from coastal erosion is strongly dependent on climate state, corroborating predictions of enhanced coastal erosion during future sea-level rise.

scholarly journals Supplemental Material: Detrital signals of coastal erosion and fluvial sediment supply during glacio-eustatic sea-level rise, Southern California, USA

2021 ◽  
Author(s):  
Glenn Sharman ◽  
et al.
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Erosion ◽  
Southern California ◽  
Mixture Modeling ◽  
Sediment Supply ◽  
Analytical Methodology ◽  
Fluvial Sediment ◽  
Icp Ms ◽  
Data Tables

Sample summary, LA-ICP-MS data tables, sources of Cretaceous-Paleogene forearc data, Peninsular Ranges batholith zircon U-Pb ages, mixture modeling results, and U-Pb analytical methodology.<br>

scholarly journals Supplemental Material: Detrital signals of coastal erosion and fluvial sediment supply during glacio-eustatic sea-level rise, Southern California, USA

2021 ◽  
Author(s):  
Glenn Sharman ◽  
et al.
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Erosion ◽  
Southern California ◽  
Mixture Modeling ◽  
Sediment Supply ◽  
Analytical Methodology ◽  
Fluvial Sediment ◽  
Icp Ms ◽  
Data Tables

Sample summary, LA-ICP-MS data tables, sources of Cretaceous-Paleogene forearc data, Peninsular Ranges batholith zircon U-Pb ages, mixture modeling results, and U-Pb analytical methodology.<br>

scholarly journals Supplemental Material: Detrital signals of coastal erosion and fluvial sediment supply during glacio-eustatic sea-level rise, Southern California, USA

2021 ◽  
Author(s):  
Glenn Sharman ◽  
et al.
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Erosion ◽  
Southern California ◽  
Mixture Modeling ◽  
Sediment Supply ◽  
Analytical Methodology ◽  
Fluvial Sediment ◽  
Icp Ms ◽  
Data Tables

Sample summary, LA-ICP-MS data tables, sources of Cretaceous-Paleogene forearc data, Peninsular Ranges batholith zircon U-Pb ages, mixture modeling results, and U-Pb analytical methodology.<br>

scholarly journals Supplemental Material: Detrital signals of coastal erosion and fluvial sediment supply during glacio-eustatic sea-level rise, Southern California, USA

2021 ◽  
Author(s):  
Glenn Sharman ◽  
et al.
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Erosion ◽  
Southern California ◽  
Mixture Modeling ◽  
Sediment Supply ◽  
Analytical Methodology ◽  
Fluvial Sediment ◽  
Icp Ms ◽  
Data Tables

Sample summary, LA-ICP-MS data tables, sources of Cretaceous-Paleogene forearc data, Peninsular Ranges batholith zircon U-Pb ages, mixture modeling results, and U-Pb analytical methodology.<br>

Groins, sand retention, and the future of Southern California’s beaches

Shore & Beach ◽  
2020 ◽  
pp. 14-36
Author(s):  
Gary Griggs ◽  
Kiki Patsch ◽  
Charles Lester ◽  
Ryan Anderson
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Southern California ◽  
Beach Sand ◽  
Submarine Canyons ◽  
Littoral Drift ◽  
Short Supply ◽  
Land Use Decisions ◽  
Coastal Cliffs ◽  
Retention Structures

Beaches form a significant component of the economy, history, and culture of southern California. Yet both the construction of dams and debris basins in coastal watersheds and the armoring of eroding coastal cliffs and bluffs have reduced sand supply. Ultimately, most of this beach sand is permanently lost to the submarine canyons that intercept littoral drift moving along this intensively used shoreline. Each decade the volume of lost sand is enough to build a beach 100 feet wide, 10 feet deep and 20 miles long, or a continuous beach extending from Newport Bay to San Clemente. Sea-level rise will negatively impact the beaches of southern California further, specifically those with back beach barriers such as seawalls, revetments, homes, businesses, highways, or railroads. Over 75% of the beaches in southern California are retained by structures, whether natural or artificial, and groin fields built decades ago have been important for local beach growth and stabilization efforts. While groins have been generally discouraged in recent decades in California, and there are important engineering and environmental considerations involved prior to any groin construction, the potential benefits are quite large for the intensively used beaches and growing population of southern California, particularly in light of predicted sea-level rise and public beach loss. All things considered, in many areas groins or groin fields may well meet the objectives of the California Coastal Act, which governs coastal land-use decisions. There are a number of shoreline areas in southern California where sand is in short supply, beaches are narrow, beach usage is high, and where sand retention structures could be used to widen or stabilize local beaches before sand is funneled offshore by submarine canyons intercepting littoral drift. Stabilizing and widening the beaches would add valuable recreational area, support beach ecology, provide a buffer for back beach infrastructure or development, and slow the impacts of a rising sea level.

scholarly journals Contributions of Organic and Mineral Matter to Vertical Accretion in Tidal Wetlands across a Chesapeake Bay Subestuary

2021 ◽  
Vol 9 (7) ◽  
pp. 751
Author(s):  
Jenny R. Allen ◽  
Jeffrey C. Cornwell ◽  
Andrew H. Baldwin
Keyword(s):  
Organic Matter ◽  
Sea Level Rise ◽  
Chesapeake Bay ◽  
Sea Level ◽  
210Pb Dating ◽  
Sediment Supply ◽  
Mineral Matter ◽  
Tidal Wetlands ◽  
Vertical Accretion ◽  
Inorganic Matter

Persistence of tidal wetlands under conditions of sea level rise depends on vertical accretion of organic and inorganic matter, which vary in their relative abundance across estuarine gradients. We examined the relative contribution of organic and inorganic matter to vertical soil accretion using lead-210 (210Pb) dating of soil cores collected in tidal wetlands spanning a tidal freshwater to brackish gradient across a Chesapeake Bay subestuary. Only 8 out of the 15 subsites had accretion rates higher than relative sea level rise for the area, with the lowest rates of accretion found in oligohaline marshes in the middle of the subestuary. The mass accumulation of organic and inorganic matter was similar and related (R2 = 0.37). However, owing to its lower density, organic matter contributed 1.5–3 times more toward vertical accretion than inorganic matter. Furthermore, water/porespace associated with organic matter accounted for 82%–94% of the total vertical accretion. These findings demonstrate the key role of organic matter in the persistence of coastal wetlands with low mineral sediment supply, particularly mid-estuary oligohaline marshes.

Feasibility of sedimentation strategies for the Mekong delta to counterbalance relative sea-level rise

2021 ◽  
Author(s):  
Frances E. Dunn ◽  
Philip S. J. Minderhoud
Keyword(s):  
Land Use ◽  
Sea Level Rise ◽  
Sea Level ◽  
Mekong Delta ◽  
Sediment Deposition ◽  
Sediment Supply ◽  
Sediment Flux ◽  
Relative Sea Level ◽  
Fluvial Sediment ◽  
Relative Sea Level Rise

&lt;p&gt;As one of the largest deltas in the world, the Mekong delta is home to over 17 million people and supports internationally important agriculture. Recently deposited sediment compacts and causes subsidence in deltas, so they require regular sediment input to maintain elevation relative to sea level. These processes are complicated by human activities, which prevent sediment deposition indirectly through reducing fluvial sediment supply and directly through the construction of flood defence infrastructure on deltas, impeding floods which deliver sediment to the land. Additionally, anthropogenic activities increase the rate of subsidence through the extraction of groundwater and other land-use practices.&lt;/p&gt;&lt;p&gt;This research shows the potential for fluvial sediment delivery to compensate for sea-level rise and subsidence in the Mekong delta over the 21st century. We use detailed elevation data and subsidence scenarios in combination with regional sea-level rise and fluvial sediment flux projections to quantify the potential for maintaining elevation relative to sea level in the Mekong delta. We present four examples of localised sedimentation scenarios in specific areas, for which we quantified the potential effectiveness of fluvial sediment deposition for offsetting relative sea-level rise. The presented sediment-based adaptation strategies are complicated by existing land use, therefore a change in water and sediment management is required to effectively use natural resources and employ these adaptation methods. The presented approach could be an exemplar to assess sedimentation strategy feasibility in other delta systems worldwide that are under threat from sea-level rise.&lt;/p&gt;

scholarly journals Holocene sea level and climate interactions on wet dune slack evolution in SW Portugal: A model for future scenarios?

The Holocene ◽  
2018 ◽  
Vol 29 (1) ◽  
pp. 26-44 ◽  
Author(s):  
Manel Leira ◽  
Maria C Freitas ◽  
Tania Ferreira ◽  
Anabela Cruces ◽  
Simon Connor ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Environmental Changes ◽  
Sediment Accumulation ◽  
High Energy ◽  
Sediment Supply ◽  
Dune Slack ◽  
Ecological Stability ◽  
The Holocene ◽  
Climate Interactions

We examine the Holocene environmental changes in a wet dune slack of the Portuguese coast, Poço do Barbarroxa de Baixo. Lithology, organic matter, biological proxies and high-resolution chronology provide estimations of sediment accumulation rates and changes in environmental conditions in relation to sea-level change and climate variability during the Holocene. Results show that the wet dune slack was formed 7.5 cal. ka BP, contemporaneous with the last stages of the rapid sea-level rise. This depositional environment formed under frequent freshwater flooding and water ponding that allowed the development and post-mortem accumulation of abundant plant remains. The wetland evolved into mostly palustrine conditions over the next 2000 years, until a phase of stabilization in relative sea-level rise, when sedimentation rates slowed down to 0.04 mm yr−1, between 5.3 and 2.5 cal. ka BP. Later, about 0.8 cal. ka BP, high-energy events, likely due to enhanced storminess and more frequent onshore winds, caused the collapse of the foredune above the wetlands’ seaward margin. The delicate balance between hydrology (controlled by sea-level rise and climate change), sediment supply and storminess modulates the habitat’s resilience and ecological stability. This underpins the relevance of integrating past records in coastal wet dune slacks management in a scenario of constant adaptation processes.

Sign in / Sign up

Export Citation Format

Share Document