scholarly journals Monitoring Retreat of Coastal Sandy Systems Using Geomatics Techniques: Somo Beach (Cantabrian Coast, Spain, 1875–2017)

2018 ◽  
Vol 10 (9) ◽  
pp. 1500 ◽  
Author(s):  
José de Sanjosé Blasco ◽  
Manuel Gómez-Lende ◽  
Manuel Sánchez-Fernández ◽  
Enrique Serrano-Cañadas
Keyword(s):  
Laser Scanning ◽  
Meteorological Data ◽  
Tidal Range ◽  
Data Series ◽  
Global Changes ◽  
Estuarine System ◽  
Level Curve ◽  
Dune System ◽  
Human Environment ◽  
Historical Cartography

The dynamics and evolution of a coastal sandy system over the last 142 years (1875–2017) were analyzed using geomatics techniques (historical cartography, photogrammetry, topography, and terrestrial laser scanning (TLS)). The continuous beach–dune system is a very active confining sand barrier closing an estuarine system where damage is suffered by coastal infrastructures and houses. The techniques used and documentary sources involved historical cartography, digitalizing the 5-m-level curve on the maps of 1875, 1908, 1920, 1950, and 1985; photogrammetric flights of 1985, 1988, and 2001 without calibration certificates, digitalizing only the upper part of the sandy front; photogrammetric flights of 2005, 2007, 2010, and 2014, using photogrammetric restitution of the 5-m-level curve; topo-bathymetric profiles made monthly between 1988 and 1993 using a total station; a terrestrial laser scanner (TLS) since 2011 by means of two annual measurements; and the meteorological data for the period of 1985–2017. The retreat of the sandy complex was caused by winter storms with large waves and swells higher than 6 m, coinciding with periods demonstrating a high tidal range of over 100 and periods with a large number of strong storms. The retreat was 8 m between December 2013 and March 2014. The overall change of the coastline between 1875 and 2017 was approximately 415 m of retreat at Somo Beach. The erosive processes on the foredune involved the outcrop of the rock cliff in 1999 and 2014, which became a continuous rocky cliff without sands. To know the recent coastal evolution and its consequences on the human environment, the combined geomatic techniques and future TLS data series may lead to the improvement in the knowledge of shoreline changes in the context of sea level and global changes.

scholarly journals The Use of Hydrodynamic Models in the Determination of the Chart Datum Shape in a Tropical Estuary

Water ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 902 ◽  
Author(s):  
Carlos Zapata ◽  
Araceli Puente ◽  
Andrés García ◽  
Javier García-Alba ◽  
Jorge Espinoza
Keyword(s):  
Hydrodynamic Model ◽  
Nonlinear Effects ◽  
Tidal Range ◽  
Data Series ◽  
Estuarine System ◽  
Hydrodynamic Models ◽  
Level Data ◽  
Anthropogenic Action ◽  
Port Construction

Estuaries are transitional environments with ideal conditions for port construction and navigation. They represent a challenge to hydrographic services due to the dynamics of the seabed and the tidal wave deformation. The bottom slope, the convergence of the channels, and the nonlinear effects produced by the bottom friction produce variation in both the tidal range and the location of the chart datum (CD). In this study, sea level data series obtained from the nodes of the mesh of a hydrodynamic model (virtual tide gauges) were used to calculate the harmonic constituents, form factor, asymmetry, and estuary type. The final chart datum surface, obtained from the hydrodynamic model, was used to determine the separation values between zones and also the number of tidal zones in an estuarine system. It was found that in a complex hydrodynamics scenario, the use of the ellipsoidal referenced surveying (ERS) method is more convenient than traditional tidal zoning survey. In the ERS method, once the CD model is complete, it must be attached to the ellipsoid directly. Finally, the variation of the CD in different scenarios (due to anthropogenic action) was assessed.

scholarly journals OBSERVATIONS OF BEACH-DUNE MORPHOGOLICAL RESPONSE TO STORM WAVES USING LIDAR BATHYMETRIC MAPPING IN A WAVE BASIN

2018 ◽  
pp. 5
Author(s):  
Ramy Y. Marmoush ◽  
Ryan P. Mulligan
Keyword(s):  
Laser Scanning ◽  
Sand Dune ◽  
Dune System ◽  
Sand Beach ◽  
Coastal Morphology ◽  
3 Dimensional ◽  
Storm Waves ◽  
Impact Scale ◽  
Wave Basin ◽  
Run Up

Waves during major storms can cause significant changes to coastal morphology (Lee et al., 1998). The beach-dune system is known to be highly vulnerable to erosion when the wave run-up exceeds the threshold of the base of the dune in the collision regime, according to the Storm Impact scale defined by Sallenger (2000). Detailed bathymetric measurements are very difficult to obtain during storms due to the hazardous wave conditions. However, bathymetric surveys can be easily and intermittently performed during smaller scale physical model experiments (e.g., Hamilton et al., 2001) and high resolution can be achieved using laser scanning with Light Detection and Ranging (LIDAR) sensors (Smith et al., 2017). In the present study, a laboratory experiment of beach-dune morphology change is conducted in a rectangular wave basin that has recently been used to simulate erosion of a 2-dimensional sand dune (Berard et al., 2017). The objective of the present study is to investigate the 3-dimensional morphologic response of a sand beach-dune system to storm waves approaching at an oblique angle.

scholarly journals Spatial Variation in Coastal Dune Evolution in a High Tidal Range Environment

2020 ◽  
Vol 12 (22) ◽  
pp. 3689
Author(s):  
Iain Fairley ◽  
Jose Horrillo-Caraballo ◽  
Ian Masters ◽  
Harshinie Karunarathna ◽  
Dominic E. Reeve
Keyword(s):  
Spatial Scales ◽  
Coastal Dunes ◽  
Sediment Supply ◽  
Tidal Range ◽  
Coastal Protection ◽  
Dune System ◽  
Pressure Transducers ◽  
Significant Wave ◽  
Wave Heights ◽  
Significant Wave Heights

Coastal dunes have global importance as ecological habitats, recreational areas, and vital natural coastal protection. Dunes evolve due to variations in the supply and removal of sediment via both wind and waves, and on stabilization through vegetation colonization and growth. One aspect of dune evolution that is poorly understood is the longshore variation in dune response to morphodynamic forcing, which can occur over small spatial scales. In this paper, a fixed wing unmanned aerial vehicle (UAV), is used to measure the longshore variation in evolution of a dune system in a megatidal environment. Dune sections to the east and west of the study site are prograding whereas the central portion is static or eroding. The measured variation in dune response is compared to mesoscale intertidal bar migration and short-term measurements of longshore variation in wave characteristics during two storms. Intertidal sand bar migration is measured using satellite imagery: crescentic intertidal bars are present in front of the accreting portion of the beach to the west and migrate onshore at a rate of 0.1–0.2 m/day; episodically the eastern end of the bar detaches from the main bar and migrates eastward to attach near the eastern end of the study area; bypassing the central eroding section. Statistically significant longshore variation in intertidal wave heights were measured using beachface mounted pressure transducers: the largest significant wave heights are found in front of the dune section suffering erosion. Spectral differences were noted with more narrow-banded spectra in this area but differences are not statistically significant. These observations demonstrate the importance of three-dimensionality in intertidal beach morphology on longshore variation in dune evolution; both through longshore variation in onshore sediment supply and through causing longshore variation in near-dune significant wave heights.

Longshore variation in coastal foredune growth on a megatidal beach from UAV measurements

2020 ◽  
Author(s):  
Iain Fairley ◽  
Jose Horrillo-Caraballo ◽  
Anouska Mendzil ◽  
Georgie Blow ◽  
Henry Miller ◽  
...  
Keyword(s):  
Wave Energy ◽  
Point Cloud ◽  
High Tide ◽  
Tidal Range ◽  
Dune System ◽  
Wave Heights ◽  
Upper Intertidal ◽  
Rtk Gps ◽  
Swansea Bay ◽  
Dune Area

<p>Coastal dunes are both a vital natural coastal defence and a key ecological habitat; therefore, understanding their evolution is important to inform coastal management. Megatidal environments are the world largest tidal ranges and hence provide a unique endmember of the tidal range continuum. A study site at Crymlyn Burrows, Swansea Bay, UK is monitored here; the area was originally of applied interest due to its identification as a key receptor of the Swansea Bay Tidal Lagoon project. The study site comprises of 2km of dune frontage bounded to the west by hard sea defences and to the east by the River Neath estuary. The intertidal is characterized by a shallow slope and crescentic intertidal bars. Mean spring tidal range at the nearby Mumbles tide gauge is 8.46m; mean wave heights at a wave buoy offshore of the site (depth 9m LAT) are 0.66m and storm wave heights exceed 3m; predominant wind direction is in an alongshore – onshore direction.</p><p>A Sensefly Ebee-RTK drone with a Sony RGB camera has been used to map the dune system and the mid to upper intertidal beach on a monthly – bimonthly frequency since October 2018. Initial post-processing was conducted in the Sensefly Emotion3 software; Pix4D was then used to generate a point cloud from the georeferenced images. RTK-GPS surveyed ground control points distributed over the study area were used to improve the accuracy of the solution. Point clouds were cleaned to remove noise using Cloud Compare, an open source point cloud editor, before being interpolated onto a gridded surface. Comparison of the gridded surface against RTK-GPS surveyed points gave a vertical mean absolute error (MAE) of 0.05m over the beach area. Comparison in the dune area is more complex since the raw point cloud includes the vegetation and hence over-estimates height compared to the bare earth. Based on the raw point cloud, MAE over the dune area was 0.22m; however, when vegetation points were removed using artificial neural network based colour discrimination, the MAE was 0.05m.</p><p>Longshore variation in dune evolution is clearly evident. At the eastern and western ends of the dune system, dune progradation can be observed whereas in the central portion the frontal dune is cliffed and the dune foot position is static or eroding landward. Pressure transducers have been deployed in a longshore array at the neap high tide level to assess variation in wave energy reaching the upper intertidal over the study area.</p><p>This presentation will explore whether this variation in behavior is due to longshore variation in wave energy (erosion potential), variation in sediment availability (accretion potential) or the persistence of antecedent morphology.</p>

A relative sea-level history for Arviat, Nunavut, and implications for Laurentide Ice Sheet thickness west of Hudson Bay

2014 ◽  
Vol 82 (1) ◽  
pp. 185-197 ◽  
Author(s):  
Karen M. Simon ◽  
Thomas S. James ◽  
Donald L. Forbes ◽  
Alice M. Telka ◽  
Arthur S. Dyke ◽  
...  
Keyword(s):  
Sea Level ◽  
Late Holocene ◽  
Ice Sheet ◽  
Tidal Range ◽  
Laurentide Ice Sheet ◽  
Hudson Bay ◽  
Level Curve ◽  
Relative Sea Level ◽  
Vertical Land Motion ◽  
Crustal Uplift

AbstractThirty-six new and previously published radiocarbon dates constrain the relative sea-level history of Arviat on the west coast of Hudson Bay. As a result of glacial isostatic adjustment (GIA) following deglaciation, sea level fell rapidly from a high-stand of nearly 170 m elevation just after 8000 cal yr BP to 60 m elevation by the mid Holocene (~ 5200 cal yr BP). The rate of sea-level fall decreased in the mid and late Holocene, with sea level falling 30 m since 3000 cal yr BP. Several late Holocene sea-level measurements are interpreted to originate from the upper end of the tidal range and place tight constraints on sea level. A preliminary measurement of present-day vertical land motion obtained by repeat Global Positioning System (GPS) occupations indicates ongoing crustal uplift at Arviat of 9.3 ± 1.5 mm/yr, in close agreement with the crustal uplift rate inferred from the inferred sea-level curve. Predictions of numerical GIA models indicate that the new sea-level curve is best fit by a Laurentide Ice Sheet reconstruction with a last glacial maximum peak thickness of ~ 3.4 km. This is a 30–35% thickness reduction of the ICE-5G ice-sheet history west of Hudson Bay.

Mathematical tidal model of the Tay Estuary

1980 ◽  
Vol 78 (3-4) ◽  
pp. s171-s182
Author(s):  
D. J. A. Williams ◽  
V. Nassehi
Keyword(s):  
Mathematical Model ◽  
Finite Difference ◽  
Tidal Range ◽  
Level Curve ◽  
Tidal Level ◽  
Tidal Model ◽  
One Dimensional ◽  
Implicit Finite Difference Scheme ◽  
Implicit Finite Difference ◽  
Tay Estuary

SynopsisA one-dimensional mathematical model based on an implicit finite difference scheme is used to predict tidal levels and discharges throughout the Tay Estuary. The model accounts for the transformation of the tidal level curve along the estuary and predicts a maximum tidal range near Flisk. There is a measure of agreement between computed velocities and observed data in the upper reaches of the estuary.

scholarly journals Best Fitted Distribution For Meteorological Data In Kuala Krai

2021 ◽  
Vol 3 (1) ◽  
pp. 16-25
Author(s):  
Siti Mariam Norrulashikin ◽  
Fadhilah Yusof ◽  
Siti Rohani Mohd Nor ◽  
Nur Arina Bazilah Kamisan
Keyword(s):  
Climate Change ◽  
Probability Distribution ◽  
Goodness Of Fit ◽  
Probability Distributions ◽  
Meteorological Data ◽  
Cumulative Distribution ◽  
Distribution Model ◽  
Data Series ◽  
Distribution Models ◽  
Goodness Of Fit Tests

Modeling meteorological variables is a vital aspect of climate change studies. Awareness of the frequency and magnitude of climate change is a critical concern for mitigating the risks associated with climate change. Probability distribution models are valuable tools for a frequency study of climate variables since it measures how the probability distribution able to fit well in the data series. Monthly meteorological data including average temperature, wind speed, and rainfall were analyzed in order to determine the most suited probability distribution model for Kuala Krai district. The probability distributions that were used in the analysis were Beta, Burr, Gamma, Lognormal, and Weibull distributions. To estimate the parameters for each distribution, the maximum likelihood estimate (MLE) was employed. Goodness-of-fit tests such as the Kolmogorov-Smirnov, and Anderson-Darling tests were conducted to assess the best suited model, and the test's reliability. Results from statistical studies indicate that Burr distributions better characterize the meteorological data of our research. The graph of probability density function, cumulative distribution function as well as Q-Q plot are presented.

scholarly journals Análise comparativa da velocidade do vento e da temperatura do ar, entre dados gerados por reanálises meteorológicas e dados observacionais na região de Minas Gerais

2018 ◽  
Vol 40 ◽  
pp. 20
Author(s):  
Mauren Lucila Marques de Morais Micalichen ◽  
Nelson Luís da Costa Dias
Keyword(s):  
Wind Speed ◽  
Air Temperature ◽  
Meteorological Data ◽  
Reanalysis Data ◽  
Minas Gerais ◽  
Data Series ◽  
Continuous Series ◽  
Observation Data ◽  
Alternative Source ◽  
Wind Speed Data

The use of alternative sources of meteorological data has become increasingly common, making it possible to evaluate areas with no long or continuous series of meteorological data. In this context, the main objective of this study is to evaluate the performance of data series from the National Centers for Environmental Prediction / National Center for Atmospheric Research (NCEP/NCAR) for the state of Minas Gerais and verify the possible use of them in the absence of data observations of air temperature and wind speed. The analyzes were performed by comparing observation data from 17 meteorological stations and reanalysis data of the CFSR and CFSV2 models. From the results of the statistical analysis, it is observed that the air temperature reanalysis data presented a good performance in the region of study. However, wind speed data show a weak correlation. These results show that the air temperature data from these reanalyses have the potential to be used as an alternative source of data. Further studies are suggested regarding the use of wind speed data from these reanalyses.

scholarly journals Modeling spatially distributed snow instability at a regional scale using Alpine3D

2021 ◽  
pp. 1-16
Author(s):  
Bettina Richter ◽  
Jürg Schweizer ◽  
Mathias W. Rotach ◽  
Alec van Herwijnen
Keyword(s):  
Laser Scanning ◽  
Meteorological Data ◽  
Regional Scale ◽  
Winter Season ◽  
Horizontal Resolution ◽  
Distributed Modeling ◽  
Avalanche Forecasting ◽  
Weak Layer ◽  
Snow Stratigraphy ◽  
Spatially Distributed

Abstract Assessing the avalanche danger level requires snow stratigraphy and instability data. As such data are usually sparse, we investigated whether distributed snow cover modeling can be used to provide information on spatial instability patterns relevant for regional avalanche forecasting. Using Alpine3D, we performed spatially distributed simulations to evaluate snow instability for the winter season 2016–17 in the region of Davos, Switzerland. Meteorological data from automatic weather stations were interpolated to 100 m horizontal resolution and precipitation was scaled with snow depth measurements from airborne laser scanning. Modeled snow instability metrics assessed for two different weak layers suggested that the weak layer closer to the snow surface was more variable. Initially, it was less stable than the weak layer closer to the ground, yet it stabilized faster as the winter progressed. In spring, the simulated snowpack on south-facing slopes stabilized faster than on north-facing slopes, in line with the regional avalanche forecast. In the winter months January to March 2017, simulated instability metrics did not suggest that the snowpack on south-facing slopes was more stable, as reported in the regional avalanche forecast. Although a validation with field data is lacking, these model results still show the potential and challenges of distributed modeling for supporting operational avalanche forecasting.

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