scholarly journals EXPLORING THE INFLUENCE OF LAND RECLAMATION ON SEDIMENT GRAIN SIZE DISTRIBUTION ON TIDAL FLATS: A NUMERICAL STUDY

2018 ◽  
pp. 85
Author(s):  
Lei Chen ◽  
Zeng Zhou ◽  
Mengpiao Xu ◽  
Fan Xu ◽  
Jianfeng Tao ◽  
...  
Keyword(s):  
Grain Size ◽  
Tidal Flat ◽  
Land Reclamation ◽  
State Of The Art ◽  
Numerical Study ◽  
Morphological Evolution ◽  
Sediment Grain Size ◽  
Fine Sediments ◽  
Sediment Sorting ◽  
Flat Profile

We explore the effects of land reclamation on the morphological evolution and sediment sorting on a tidal flat using a state-of-the-art numerical model (Delft3D). Consistent with existing field observations and analytical theories, model results indicate that the longitudinal profile adjusts itself converging to new equilibrium states (narrower and steeper) after a series of reclamations. Relatively fine sediments deposit adjacent to the sea dike, due to the flood-dominated tidal hydrodynamics. The amount of sediment deposition in front of the dike peaks when the dike is designed at mean sea level. After sequential reclamations, sediment grain size appears to be coarser offshore and on the tidal flat. Overall, this study suggests that land reclamation can lead to the readjustment of tidal flat profile shapes and coarsening of sediment grain size, which should be taken into account when reclamation projects are planned.

Late Holocene Lake Sedimentology and Climate Change in Southern Alberta, Canada

1998 ◽  
Vol 49 (1) ◽  
pp. 96-101 ◽  
Author(s):  
Celina Campbell
Keyword(s):  
Grain Size ◽  
Ice Age ◽  
Low Flow ◽  
Sediment Grain Size ◽  
High Discharge ◽  
Climate Fluctuations ◽  
Fine Grained ◽  
Fine Sediments ◽  
Southern Alberta ◽  
Paleoclimate Proxy

Climatic changes in southern Alberta, Canada, for the past 4000 yr are reflected in a high-resolution record of lake sediment grain size. The proposed mechanism for this response is that outflow discharge removes fine-grained sediments, but increasingly fine sediments are retained and deposited as streamflow declines. At the same time, coarse sediments are brought in by high discharge entering the lake. The net effect of these two processes is to leave coarse, clay-deficient sediments during times of high streamflow and clay-rich sediments during times of low flow. The grain-size record from Pine Lake reflects historic climate fluctuations, as well as prehistoric fluctuations including the Little Ice Age and the Medieval Warm Period. Grain size at this site provides a simple, economical, and nonbiologically mediated paleoclimate proxy.

scholarly journals Response of tidal flow regime and sediment transport in North Male' Atoll, Maldives to coastal modification and sea level rise

2020 ◽  
Author(s):  
Shuaib Rasheed ◽  
Simon C. Warder ◽  
Yves Plancherel ◽  
Matthew D. Piggott
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Sea Level Rise ◽  
Sea Level ◽  
Land Reclamation ◽  
Tidal Flow ◽  
Sediment Grain Size ◽  
Sediment Distribution ◽  
Time Periods ◽  
The Impact

Abstract. Changes to coastlines and bathymetry alter tidal dynamics and associated sediment transport process, impacting upon a number of threats facing coastal regions, including flood risk and erosion. Especially vulnerable are coral atolls such as those that make up the Maldives archipelago which has undergone significant land reclamation in recent years and decades, and is also particularly exposed to sea level rise. Here we develop a tidal model of Male' Atoll, Maldives, and use it to assess potential changes to sediment grain size distributions under sea level rise and coastline alteration scenarios. The results indicate that the impact of coastline modification over the last two decades at the island scale is not limited to the immediate vicinity of the modified island, but can also significantly impact the sediment grain size distribution across the wider atoll basin. Additionally, the degree of change in sediment distribution which can be associated with sea level rise that is projected to occur over relatively long time periods is predicted to occur over far shorter time periods with coastline changes, highlighting the need to better understand, predict and mitigate the impact of land reclamation and other coastal modifications before conducting such activities.

scholarly journals Response of tidal flow regime and sediment transport in North Malé Atoll, Maldives, to coastal modification and sea level rise

Ocean Science ◽  
2021 ◽  
Vol 17 (1) ◽  
pp. 319-334
Author(s):  
Shuaib Rasheed ◽  
Simon C. Warder ◽  
Yves Plancherel ◽  
Matthew D. Piggott
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Sea Level Rise ◽  
Sea Level ◽  
Land Reclamation ◽  
Transport Processes ◽  
Sediment Grain Size ◽  
Sediment Distribution ◽  
Time Periods ◽  
The Impact

Abstract. Changes to coastlines and bathymetry alter tidal dynamics and associated sediment transport processes, impacting upon a number of threats facing coastal regions, including flood risk and erosion. Especially vulnerable are coral atolls such as those that make up the Maldives archipelago, which has undergone significant land reclamation in recent years and decades and is also particularly exposed to sea level rise. Here we develop a tidal model of Malé Atoll, Maldives, the first atoll-scale and multi-atoll-scale high-resolution numerical model of the atolls of the Maldives and use it to assess potential changes to sediment grain size distributions in the deeper atoll basin, under sea level rise and coastline alteration scenarios. The results indicate that the impact of coastline modification over the last two decades at the island scale is not limited to the immediate vicinity of the modified island but can also significantly impact the sediment grain size distribution across the wider atoll basin. Additionally, the degree of change in sediment distribution which can be associated with sea level rise that is projected to occur over relatively long time periods is predicted to occur over far shorter time periods with coastline changes, highlighting the need to better understand, predict and mitigate the impact of land reclamation and other coastal modifications before conducting such activities.

Stepwise morphological evolution of the active Yellow River (Huanghe) delta lobe (1976–2013): Dominant roles of riverine discharge and sediment grain size

Geomorphology ◽  
2017 ◽  
Vol 292 ◽  
pp. 115-127 ◽  
Author(s):  
Xiao Wu ◽  
Naishuang Bi ◽  
Jingping Xu ◽  
Jeffrey A. Nittrouer ◽  
Zuosheng Yang ◽  
...  
Keyword(s):  
Grain Size ◽  
Yellow River ◽  
Morphological Evolution ◽  
Sediment Grain Size ◽  
Riverine Discharge ◽  
Delta Lobe

Effects of aeration, sediment grain size and burial on stream litter breakdown and consumer performance: a microcosm study

2017 ◽  
Vol 68 (12) ◽  
pp. 2266 ◽  
Author(s):  
Olatz Pereda ◽  
Maite Arroita ◽  
Ibon Aristi ◽  
Lorea Flores ◽  
Aitor Larrañaga ◽  
...  
Keyword(s):  
Grain Size ◽  
Hyporheic Zone ◽  
Food Resource ◽  
Low Flow ◽  
Sediment Grain Size ◽  
Water Abstraction ◽  
Fine Sediments ◽  
Sediment Size ◽  
Microcosm Study ◽  
Laboratory Microcosm

Turbulence and aeration are reduced in many streams during low-flow periods as a consequence of drought or water abstraction, thus affecting invertebrate interactions and pivotal ecosystem processes such as the breakdown of organic matter (OM). These effects can be larger in the hyporheic zone (HZ), the ecotone connecting the surface stream and groundwater, especially when fine sediments reduce hydraulic conductivity. In addition, OM breakdown in the HZ could depend on the availability of OM in the benthic zone (BZ), because the latter would not only be a more accessible, and thus preferred, food resource, but also more easily scoured downstream. In a laboratory microcosm experiment of 28 days duration, we manipulated aeration, sediment size and location of OM (either all buried or half buried with half on the surface, simulating the HZ and BZ respectively). Six mayfly (Habroleptoides) individuals and four stonefly (Capnioneura) individuals were enclosed in each microcosm and the consumption of OM was measured. Lack of aeration reduced oxygen saturation from 94 to 66%, reducing OM consumption particularly on the surface, in contrast with our expectations. As hypothesised, the availability of surface OM significantly reduced invertebrate consumption of buried OM. Habroleptoides performed better than Capnioneura, especially in fine sediments. The results suggest that reduced turbulence can affect invertebrate trophic interactions as well as the decomposition of OM, depending on sediment grain size and the location of OM.

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