scholarly journals On the faunas inhabiting intertidal seaweeds

1940 ◽  
Vol 24 (1) ◽  
pp. 129-183 ◽  
Author(s):  
John Colman
Keyword(s):  
Sea Level ◽  
High Water ◽  
Laminaria Digitata ◽  
Marine Fauna ◽  
Mean Sea Level ◽  
Water Springs

This paper gives an account of a survey of the invertebrate populations (omitting Protozoa) of eight species of seaweeds on Church Reef, Wembury Bay, extending over the entire intertidal range.Above high-water neaps the faunas are poor, except for that in Lichina pygmaea which is the richest in individuals on the shore.Between high-water neaps and low-water springs the most numerous groups are copepods, acarines, young littorinids and (in Ascophyllum only) ostracods.In the holdfasts of Laminaria digitata polychaetes are very abundant and make up the majority of the population.The intertidal faunas are compared with those in the soil on land, and prove to be far more abundant. Even the most plentiful group in the soil, the insects, is rarely as numerous as it is in Ascophyllum around mean sea-level.Altogether 177 species are recorded, of which 35 are not in the Plymouth Marine Fauna (1931).

scholarly journals ANALISIS REFLEKSI DAN TRANSMISI GELOMBANG PADA PEMECAH GELOMBANG TIANG PANCANG

2020 ◽  
Vol 12 (3) ◽  
pp. 723-737
Author(s):  
Hendra Achiari ◽  
Ayu Libiaty Ahmad ◽  
Dede M Sulaiman
Keyword(s):  
Water Level ◽  
Sea Level ◽  
High Water ◽  
Mean Sea Level ◽  
High Water Level

Pantai berlumpur rentan terhadap kerusakan akibat gelombang, sehingga diperlukan perlindungan pantai yang salah satunya menggunakan pemecah gelombang tipe permeable. Tipe permeable yang dikembangkan ini disebut sebagai Pemecah Gelombang Tiang Pancang. Bahan yang digunakan untuk memodelkan struktur tersebut (prototipe) di laboratorium adalah bambu bulat bersekat yaitu bambu bulat dari taman Pringgodani dengan diameter 1 cm, tinggi 20 cm dengan sekat kayu multiblok setebal 2 cm. Analisis refleksi dan transmisi terhadap hasil pengujian model fisik 2D terhadap pemecah gelombang diperlukan untuk mencapai optimasi dalam penggunaannya. Hasil pengujian laboratorium membuktikan bahwa Pemecah Gelombang ini cukup efektif pada skenario yang memiliki nilai Kt yang lebih kecil dan nilai Kr yang lebih besar. Pada percobaan ini pengujian dilakukan dengan skenario tinggi muka air pada Mean Sea Level (MSL) (44 cm) dan High Water Level (HWL) (50 cm) dengan 2 skenario spasi antar tiang yaitu 1 cm dan 2 cm pada masing-masing tinggi muka air. Kemudian hasil perhitungan Kt dan Kr dibandingkan dengan variabel non-dimensional kecuraman gelombang (Hi/gT2) dan kemiringan gelombang (Hi/L) . Hasil percobaan laboratorium menunjukkan bahwa nilai Kt lebih rendah pada saat kondisi MSL, dan nilai Kr lebih tinggi pada saat kondisi MSL hal ini menunjukkan bahwa Pemecah Gelombang Bambu Bulat Bersekat ini lebih efektif pada muka air rendah dari pada muka air tinggi.

scholarly journals Characterization of Intertidal Bar Morphodynamics Using a Bi-Annual LiDAR Dataset

2020 ◽  
Vol 12 (22) ◽  
pp. 3841
Author(s):  
Anne-Lise Montreuil ◽  
Robrecht Moelans ◽  
Rik Houthuys ◽  
Patrick Bogaert ◽  
Margaret Chen
Keyword(s):  
Sea Level ◽  
Spatial Organization ◽  
High Water ◽  
Sandy Beaches ◽  
Wave Regime ◽  
Mean Sea Level ◽  
Beach Processes ◽  
Lower Intertidal Zone ◽  
The Mean ◽  
Annual Scale

Intertidal bars are common features on meso-and macro-tidal sandy beaches with low to moderate wave energy environments. Understanding their morphodynamics is, hence, crucial for enhancing our knowledge on beach processes which is beneficial for coastal management. However, most studies have been limited by assessing bar systems two-dimensionally and typically over the short-term. Morphology and dynamics of an intertidal bar system in a macro-tidal environment have been investigated using bi-annual LiDAR topographic surveys over a period of seven years and along 3.2 km at Groenendijk beach (Belgium). The detected bars demonstrate that a morphology of an intertidal bar is permanently on the beach. However, these individual features are dynamic and highly mobile over the course of half a year. The mean height and width of the bars were 1.1 and 82 m, respectively. The highest, steepest, and asymmetric features were found on the upper beach, while they were least developed in the lower intertidal zone. The bars were evenly distributed over the entire intertidal beach, but the largest concentration observed around the mean sea level indicated the occurrence at preferential locations. The most significant net change across the beach occurs between the mean sea level and mean-high-water neap which corroborates with the profile mobility pattern. The seasonal variability of the bar morphology is moderately related to the seasonally driven changes in storm and wave regime forcings. However, a distinct relationship may be inhibited by the complex combination of forcing-, relaxation time- and feedback-dominated response. This work conducted from bi-annual LiDAR surveys has provided an unprecedented insight into the complex spatial organization of intertidal bars as well as their variability in time from seasonal to annual scale.

scholarly journals High-Water Alerts from Coinciding High Astronomical Tide and High Mean Sea Level Anomaly in the Pacific Islands Region

2014 ◽  
Vol 31 (12) ◽  
pp. 2829-2843 ◽  
Author(s):  
Scott A. Stephens ◽  
Robert G. Bell ◽  
Douglas Ramsay ◽  
Nigel Goodhue
Keyword(s):  
Sea Level ◽  
Pacific Islands ◽  
High Water ◽  
Medium Term ◽  
Sea Level Anomaly ◽  
Mean Sea Level ◽  
Astronomical Tide ◽  
The Pacific ◽  
Level Elevation ◽  
Practical Tool

Abstract A technique to produce high-water alerts from coinciding high astronomical tide and high mean sea level anomaly is demonstrated for the Pacific Islands region. Low-lying coastal margins are vulnerable to episodic inundation that often coincides with times of higher-than-normal high tides. Prior knowledge of the dates of the highest tides can assist with efforts to minimize the impacts of increased exposure to inundation. It is shown that the climate-driven mean sea level anomaly is an important component of total sea level elevation in the Pacific Islands region, which should be accounted for in medium-term (1–7 months) sea level forecasts. An empirical technique is applied to develop a mean sea level–adjusted high-water alert calendar that accounts for both sea level components and provides a practical tool to assist with coastal inundation hazard planning and management.

Note on Selection of Coordinate Systems for Geodynamics

1975 ◽  
Vol 26 ◽  
pp. 395-407
Author(s):  
S. Henriksen
Keyword(s):  
Sea Level ◽  
The Other ◽  
Coordinate Systems ◽  
Mean Sea Level ◽  
The Earth ◽  
The One ◽  
Static Systems ◽  
Selection Of

The first question to be answered, in seeking coordinate systems for geodynamics, is: what is geodynamics? The answer is, of course, that geodynamics is that part of geophysics which is concerned with movements of the Earth, as opposed to geostatics which is the physics of the stationary Earth. But as far as we know, there is no stationary Earth – epur sic monere. So geodynamics is actually coextensive with geophysics, and coordinate systems suitable for the one should be suitable for the other. At the present time, there are not many coordinate systems, if any, that can be identified with a static Earth. Certainly the only coordinate of aeronomic (atmospheric) interest is the height, and this is usually either as geodynamic height or as pressure. In oceanology, the most important coordinate is depth, and this, like heights in the atmosphere, is expressed as metric depth from mean sea level, as geodynamic depth, or as pressure. Only for the earth do we find “static” systems in use, ana even here there is real question as to whether the systems are dynamic or static. So it would seem that our answer to the question, of what kind, of coordinate systems are we seeking, must be that we are looking for the same systems as are used in geophysics, and these systems are dynamic in nature already – that is, their definition involvestime.

scholarly journals Deterministic approach for multiple-source tsunami hazard assessment for Sines, Portugal

2015 ◽  
Vol 15 (11) ◽  
pp. 2557-2568 ◽  
Author(s):  
M. Wronna ◽  
R. Omira ◽  
M. A. Baptista
Keyword(s):  
Sea Level ◽  
Wave Height ◽  
Hazard Assessment ◽  
Test Site ◽  
Tsunami Hazard ◽  
Deterministic Approach ◽  
Flow Depth ◽  
Mean Sea Level ◽  
Tsunami Hazard Assessment ◽  
The Impact

Abstract. In this paper, we present a deterministic approach to tsunami hazard assessment for the city and harbour of Sines, Portugal, one of the test sites of project ASTARTE (Assessment, STrategy And Risk Reduction for Tsunamis in Europe). Sines has one of the most important deep-water ports, which has oil-bearing, petrochemical, liquid-bulk, coal, and container terminals. The port and its industrial infrastructures face the ocean southwest towards the main seismogenic sources. This work considers two different seismic zones: the Southwest Iberian Margin and the Gloria Fault. Within these two regions, we selected a total of six scenarios to assess the tsunami impact at the test site. The tsunami simulations are computed using NSWING, a Non-linear Shallow Water model wIth Nested Grids. In this study, the static effect of tides is analysed for three different tidal stages: MLLW (mean lower low water), MSL (mean sea level), and MHHW (mean higher high water). For each scenario, the tsunami hazard is described by maximum values of wave height, flow depth, drawback, maximum inundation area and run-up. Synthetic waveforms are computed at virtual tide gauges at specific locations outside and inside the harbour. The final results describe the impact at the Sines test site considering the single scenarios at mean sea level, the aggregate scenario, and the influence of the tide on the aggregate scenario. The results confirm the composite source of Horseshoe and Marques de Pombal faults as the worst-case scenario, with wave heights of over 10 m, which reach the coast approximately 22 min after the rupture. It dominates the aggregate scenario by about 60 % of the impact area at the test site, considering maximum wave height and maximum flow depth. The HSMPF scenario inundates a total area of 3.5 km2.

scholarly journals Tropical cyclone simulations over Bangladesh at convection permitting 4.4 km & 1.5 km resolution

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Hamish Steptoe ◽  
Nicholas Henry Savage ◽  
Saeed Sadri ◽  
Kate Salmon ◽  
Zubair Maalick ◽  
...  
Keyword(s):  
Wind Speed ◽  
Tropical Cyclone ◽  
Sea Level ◽  
Tropical Cyclones ◽  
Weather Forecasting ◽  
Sea Level Pressure ◽  
Mean Sea Level ◽  
Level Pressure ◽  
Medium Range ◽  
Gust Speed

AbstractHigh resolution simulations at 4.4 km and 1.5 km resolution have been performed for 12 historical tropical cyclones impacting Bangladesh. We use the European Centre for Medium-Range Weather Forecasting 5th generation Re-Analysis (ERA5) to provide a 9-member ensemble of initial and boundary conditions for the regional configuration of the Met Office Unified Model. The simulations are compared to the original ERA5 data and the International Best Track Archive for Climate Stewardship (IBTrACS) tropical cyclone database for wind speed, gust speed and mean sea-level pressure. The 4.4 km simulations show a typical increase in peak gust speed of 41 to 118 knots relative to ERA5, and a deepening of minimum mean sea-level pressure of up to −27 hPa, relative to ERA5 and IBTrACS data. The downscaled simulations compare more favourably with IBTrACS data than the ERA5 data suggesting tropical cyclone hazards in the ERA5 deterministic output may be underestimated. The dataset is freely available from 10.5281/zenodo.3600201.

scholarly journals Deep mantle melting, global water circulation and its implications for the stability of the ocean mass

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Shun-ichiro Karato ◽  
Bijaya Karki ◽  
Jeffrey Park
Keyword(s):  
Phase Transformation ◽  
Water Content ◽  
Sea Level ◽  
High Water ◽  
Water Circulation ◽  
Mantle Melting ◽  
High Water Content ◽  
Mineral Physics ◽  
Deep Mantle ◽  
Global Water

AbstractOceans on Earth are present as a result of dynamic equilibrium between degassing and regassing through the interaction with Earth’s interior. We review mineral physics, geophysical, and geochemical studies related to the global water circulation and conclude that the water content has a peak in the mantle transition zone (MTZ) with a value of 0.1–1 wt% (with large regional variations). When water-rich MTZ materials are transported out of the MTZ, partial melting occurs. Vertical direction of melt migration is determined by the density contrast between the melts and coexisting minerals. Because a density change associated with a phase transformation occurs sharply for a solid but more gradually for a melt, melts formed above the phase transformation depth are generally heavier than solids, whereas melts formed below the transformation depth are lighter than solids. Consequently, hydrous melts formed either above or below the MTZ return to the MTZ, maintaining its high water content. However, the MTZ water content cannot increase without limit. The melt-solid density contrast above the 410 km depends on the temperature. In cooler regions, melting will occur only in the presence of very water-rich materials. Melts produced in these regions have high water content and hence can be buoyant above the 410 km, removing water from the MTZ. Consequently, cooler regions of melting act as a water valve to maintain the water content of the MTZ near its threshold level (~ 0.1–1.0 wt%). Mass-balance considerations explain the observed near-constant sea-level despite large fluctuations over Earth history. Observations suggesting deep-mantle melting are reviewed including the presence of low-velocity anomalies just above and below the MTZ and geochemical evidence for hydrous melts formed in the MTZ. However, the interpretation of long-term sea-level change and the role of deep mantle melting in the global water circulation are non-unique and alternative models are reviewed. Possible future directions of studies on the global water circulation are proposed including geodynamic modeling, mineral physics and observational studies, and studies integrating results from different disciplines.

scholarly journals Flooding Conditions at Aveiro Port (Portugal) within the Framework of Projected Climate Change

2021 ◽  
Vol 9 (6) ◽  
pp. 595
Author(s):  
Américo Soares Ribeiro ◽  
Carina Lurdes Lopes ◽  
Magda Catarina Sousa ◽  
Moncho Gomez-Gesteira ◽  
João Miguel Dias
Keyword(s):  
Climate Change ◽  
Sea Level ◽  
Climate Change Impacts ◽  
Storm Surges ◽  
Historical Period ◽  
Return Periods ◽  
Wave Regime ◽  
Mean Sea Level ◽  
Sea Levels ◽  
Far Future

Ports constitute a significant influence in the economic activity in coastal areas through operations and infrastructures to facilitate land and maritime transport of cargo. Ports are located in a multi-dimensional environment facing ocean and river hazards. Higher warming scenarios indicate Europe’s ports will be exposed to higher risk due to the increase in extreme sea levels (ESL), a combination of the mean sea level, tide, and storm surge. Located on the west Iberia Peninsula, the Aveiro Port is located in a coastal lagoon exposed to ocean and river flows, contributing to higher flood risk. This study aims to assess the flood extent for Aveiro Port for historical (1979–2005), near future (2026–2045), and far future (2081–2099) periods scenarios considering different return periods (10, 25, and 100-year) for the flood drivers, through numerical simulations of the ESL, wave regime, and riverine flows simultaneously. Spatial maps considering the flood extent and calculated area show that most of the port infrastructures' resilience to flooding is found under the historical period, with some marginal floods. Under climate change impacts, the port flood extent gradually increases for higher return periods, where most of the terminals are at high risk of being flooded for the far-future period, whose contribution is primarily due to mean sea-level rise and storm surges.

scholarly journals Approaching Sea-Level Rise (SLR) Change: Strengthening Local Responses to Sea-Level Rise and Coping with Climate Change in Northern Mozambique

2021 ◽  
Vol 9 (2) ◽  
pp. 205
Author(s):  
Serafino Afonso Rui Mucova ◽  
Ulisses Miranda Azeiteiro ◽  
Walter Leal Filho ◽  
Carina Lurdes Lopes ◽  
João Miguel Dias ◽  
...  
Keyword(s):  
Ecosystem Services ◽  
Sea Level Rise ◽  
Sea Level ◽  
North Coast ◽  
Coastal Regions ◽  
Mean Sea Level ◽  
Representative Concentration Pathways ◽  
Local Responses ◽  
Ipcc Report ◽  
Global Estimates

Mean sea-level is expected to rise significantly by 2100 in all scenarios, including those compatible with the objectives of the Paris Climate Agreement. Global sea level rise projections indicate devastating implications for populations, ecosystem services and biodiversity. The implications of the sea-level rise (SLR) on low-lying islands and coastal regions and communities are substantial and require deep-rooted coping measures. In the absence of adequate responses for coping, Mozambique is expected to record huge losses, with an impact on the economy and development in many sectors of its coastal regions mainly in northern Mozambique. This research aimed to perform projections on SLR in Mozambique, and to understand its role and implications on the north coast of the country. SLR was estimated through the analysis of model outputs that support the global estimates of the fifth IPCC report near the Mozambican coast, for each of the four representative concentration pathways (RCPs) scenarios. Regional coastline retreat and coastal erosion were estimated through the results of global sandy coastlines projections developed by Vousdoukas. Mean sea-level rise projections indicate that regional estimates for the Mozambican coast are relative higher than global estimates (~0.05 m) for all representative concentration pathways (RCPs). Yet, we highlight significant differences in sea-level rises of 0.5 m, 0.7 m or 1.0 m by 2100 compared to the global mean. It is expected that with the increase in the mean sea level in the northern part of the Mozambican coast, erosive effects will increase, as well as the retreat of the coastline until 2100. With this, the tourism sector, settlements, ecosystem services and local populations are expected to be significantly affected by 2050, with increased threats in 2100 (RCP4.5, RCP8.5). Local responses for coping are proposed and properly discussed for the RCP4.5 and RCP8.5 scenarios through 2100.

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