scholarly journals Sedimentation and Survival of the Mekong Delta: A Case Study of Decreased Sediment Supply and Accelerating Rates of Relative Sea Level Rise

Oceanography ◽  
2017 ◽  
Vol 30 (3) ◽  
pp. 98-109 ◽  
Author(s):  
Mead Allison ◽  
◽  
Charles Nittrouer ◽  
Andrea Ogston ◽  
Julia Mullarney ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Mekong Delta ◽  
Sediment Supply ◽  
Relative Sea Level ◽  
Relative Sea Level Rise

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

<p>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.</p><p>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.</p>

scholarly journals Fluvial Sediment Supply and Relative Sea-Level Rise

2019 ◽  
pp. 103-126
Author(s):  
Stephen E. Darby ◽  
Kwasi Appeaning Addo ◽  
Sugata Hazra ◽  
Md. Munsur Rahman ◽  
Robert J. Nicholls
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Sediment Supply ◽  
Relative Sea Level ◽  
Fluvial Sediment ◽  
Relative Sea Level Rise

The interplay between relative sea-level rise and sediment supply at the distal part of the Nile littoral cell

The Holocene ◽  
2015 ◽  
Vol 26 (2) ◽  
pp. 248-264 ◽  
Author(s):  
Hadar Elyashiv ◽  
Revital Bookman ◽  
Dov Zviely ◽  
Simona Avnaim-Katav ◽  
Amir Sandler ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Distal Part ◽  
Sediment Supply ◽  
Relative Sea Level ◽  
Littoral Cell ◽  
Relative Sea Level Rise

scholarly journals Sedimentation strategies provide effective but limited mitigation of relative sea-level rise in the Mekong delta

2022 ◽  
Vol 3 (1) ◽  
Author(s):  
Frances E. Dunn ◽  
Philip S. J. Minderhoud
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Anthropogenic Activities ◽  
Mekong Delta ◽  
Relative Sea Level ◽  
Sediment Delivery ◽  
Limited Effectiveness ◽  
Relative Sea Level Rise ◽  
Present Context ◽  
Global Sea Level

AbstractThe Mekong delta is experiencing rapid environmental change due to anthropogenic activities causing accelerated subsidence, sea-level rise and sediment starvation. Consequentially, the delta is rapidly losing elevation relative to sea level. Designating specific areas for sedimentation is a suggested strategy to encourage elevation-building with nature in deltas. We combined projections of extraction-induced subsidence, natural compaction and global sea-level rise with new projections of fluvial sediment delivery to evaluate the potential effectiveness of sedimentation strategies in the Mekong delta to 2050. Our results reveal that with current rates of subsidence and sediment starvation, fluvial sediments alone can only preserve elevation locally, even under optimistic assumptions, and organic sedimentation could potentially assume a larger role. While sedimentation strategies alone have limited effectiveness in the present context, combined with enhanced organic matter retention and interventions reducing anthropogenic-accelerated subsidence, they can considerably delay future relative sea-level rise, buying the delta crucial time to adapt.

scholarly journals The Holocene evolution of the barrier and the back-barrier basins of Belgium and the Netherlands as a function of late Weichselian morphology, relative sea-level rise and sediment supply

2000 ◽  
Vol 79 (1) ◽  
pp. 3-16 ◽  
Author(s):  
Dirk J. Beets ◽  
Adam J. F. van der Spek
Keyword(s):  
The Netherlands ◽  
Sea Level Rise ◽  
Sea Level ◽  
Middle Ages ◽  
North Sea ◽  
Sediment Supply ◽  
Relative Sea Level ◽  
The North ◽  
Relative Sea Level Rise ◽  
The North Sea

AbstractFlooding of the southern part of the North Sea occurred between 9000 and 8000 BP, when the rate of relative sea-level rise was on the order of 0.7 cm per year for the Dover Strait Region and 1.6 cm per year for the area north of the Frisian Islands, forcing the shoreline to recede rapidly. When relative sea-level rise decelerated after 7000 BP for the Belgian coast and 6000 BP for the central Netherlands coast, sediment supply by the tidal currents balanced the creation of accommodation space in the estuaries and other back-barrier basins. Consequently, the barrier started to stabilize, and the tidal basins and their inlets silted up. Between 5500 and 4500 BP, the Belgian coastal plain changed into a freshwater marsh with peat accumulation, and the same happened 500–1000 years later in the western provinces of the Netherlands. The E-W running barrier/back-barrier system of the Frisian Islands in the northern Netherlands stayed open until today, however, because of lower sediment supply.The period between 4000 and 2000 BP was relatively quiet due to the strong deceleration of the rate of sea-level rise; peat cushions developed behind the barriers, which were straightened by erosion of the headlands. Major and often catastrophic flooding occurred in the Middle Ages, when the estuaries in the southwestern part of the Netherlands formed.About 226 (± 15%) × 109 m3 sediment, mostly sand, is stored in the barriers and back-barrier basins of the Netherlands, 70% of which was deposited prior to 5000 BP. About 10% of the stored sediment is estimated to be of alluvial origin. Most of the sediment is derived by the erosion of the Pleistocene basement during recession of the barriers, but tide-induced crossshore transport from the North Sea forms an additional source for the barriers and back-barriers of the west-facing coast of the Netherlands.

The existential crisis of the Mekong delta: Impact of accelerating land subsidence

2020 ◽  
Author(s):  
Philip S.J. Minderhoud ◽  
Gilles Erkens ◽  
Hans Middelkoop ◽  
Esther Stouthamer
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Land Subsidence ◽  
Mekong Delta ◽  
Relative Sea Level ◽  
Natural Processes ◽  
Existential Crisis ◽  
The World ◽  
Relative Sea Level Rise ◽  
Imminent Threat

<p>Land subsidence is one of the slowest, natural processes faced by deltas throughout the world, yet it acts as an important catalyst which exacerbates all other threats associated with relative sea-level rise, such as increased flood vulnerability and salinization. This presentation summarizes the results of five years of research on land subsidence in the Mekong delta and highlights the major advances in approaches and insights gained in subsidence processes and rates of an entire mega-delta system.</p><p>The Mekong delta is heading towards an existential crisis as land subsidence rates are rapidly accelerating over the past decades up to ~5 cm/yr. As sediment starvation in the Mekong river greatly reduces the adaptive capacity to counterbalance subsidence, this results in wide-spread loss of delta elevation. With the Mekong delta having an average elevation of less than 1 meter above local mean sea level, these elevated rates of relative sea-level rise pose an imminent threat of land loss and permanent submersion in the coming decades.</p><p>Like in many densely populated and rapidly developing coastal-deltaic areas around the world, the main anthropogenic driver that causes accelerated subsidence is the overexploitation of groundwater. A range of future delta elevation projections, considering sea-level rise and simulated groundwater extraction-induced subsidence following extraction pathways, show the dire situation of the delta in spatial-temporal explicit maps of future elevation relative to local sea level.</p><p>Adequate (ground)water management aimed at strongly reducing current extractions is key in mitigating accelerating sinking rates and crucial to ensure the survival of the Mekong delta. The window of opportunity to act is swiftly closing as the delta is rapidly running out of elevation, and therefore time.</p>

Late Quaternary sequence stratigraphy of the Mackenzie Delta

1996 ◽  
Vol 33 (7) ◽  
pp. 1053-1074 ◽  
Author(s):  
Philip R Hill
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Sequence Stratigraphy ◽  
Late Quaternary ◽  
Sediment Supply ◽  
Mackenzie Delta ◽  
Relative Sea Level ◽  
Relative Sea Level Rise ◽  
Healing Phase ◽  
Late Wisconsinan

The Late Wisconsinan and Holocene sequence stratigraphy of the Mackenzie Delta provides insights into the glacial history of the region. The base of the described succession is a hummocky regional reflector interpreted to be a flooding surface formed immediately after retreat of glacial ice from the Mackenzie Trough. Above this flooding surface, two progradational parasequences are present. The first, assigned to the transgressive systems tract, is correlated with the Tutsieta Lake readvance of the ice sheet at approximately 13 000 BP. A flooding surface forming the upper boundary of this parasequence extends inland to at least Inuvik, developing as a response to glacial retreat and early Holocene relative sea level rise. The second parasequence of Holocene deltaic deposits is assigned to the highstand systems tract and is characterized by progressive progradation of the delta into the Mackenzie Trough to a position seaward of the present delta coastline. A distinct reduction in gradient of the most recent delta clinoforms is consistent with other data suggesting regional transgression and is interpreted to represent the development of a healing-phase wedge. The reasons for this recent transgression are not clear, because relative sea level rise has decreased and sediment supply probably increased over the last 2000 years. Transgression may be related to decreased efficiency of channels, increased trapping of sediments by thermokarst lakes, overspill of the delta across the eastern margin of the valley, and (or) progressively greater exposure to wave action as the delta became less sheltered by the confines of the glacial valley.

scholarly journals Accelerated river avulsion frequency on lowland deltas due to sea-level rise

2020 ◽  
Vol 117 (30) ◽  
pp. 17584-17590 ◽  
Author(s):  
Austin J. Chadwick ◽  
Michael P. Lamb ◽  
Vamsi Ganti
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Global Climate ◽  
Sediment Supply ◽  
Flood Hazards ◽  
Relative Sea Level ◽  
River Deltas ◽  
Abrupt Changes ◽  
Relative Sea Level Rise ◽  
Coastal Land

Sea-level rise, subsidence, and reduced fluvial sediment supply are causing river deltas to drown worldwide, affecting ecosystems and billions of people. Abrupt changes in river course, called avulsions, naturally nourish sinking land with sediment; however, they also create catastrophic flood hazards. Existing observations and models conflict on whether the occurrence of avulsions will change due to relative sea-level rise, hampering the ability to forecast delta response to global climate change. Here, we combined theory, numerical modeling, and field observations to develop a mechanistic framework to predict avulsion frequency on deltas with multiple self-formed lobes that scale with backwater hydrodynamics. Results show that avulsion frequency is controlled by the competition between relative sea-level rise and sediment supply that drives lobe progradation. We find that most large deltas are experiencing sufficiently low progradation rates such that relative sea-level rise enhances aggradation rates—accelerating avulsion frequency and associated hazards compared to preindustrial conditions. Some deltas may face even greater risk; if relative sea-level rise significantly outpaces sediment supply, then avulsion frequency is maximized, delta plains drown, and avulsion locations shift inland, posing new hazards to upstream communities. Results indicate that managed deltas can support more frequent engineered avulsions to recover sinking land; however, there is a threshold beyond which coastal land will be lost, and mitigation efforts should shift upstream.

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