scholarly journals FIELD INVESTIGATION OF SEDIMENT TRANSPORT PATTERN IN A CLOSED SYSTEM

1976 ◽  
Vol 1 (15) ◽  
pp. 72
Author(s):  
Tsuguo Sunamura ◽  
Kiyoshi Horikawa
Keyword(s):  
Sediment Transport ◽  
Closed System ◽  
Shoreline Change ◽  
Field Investigation ◽  
Depositional Environments ◽  
Aerial Photographs ◽  
Beach Sand ◽  
Sieve Analysis ◽  
Alongshore Sediment Transport

In order to elucidate the transport pattern of sediment in a closed system, a pocket beach was chosen and investigated from various aspects. This investigation included the following studies: (1) bathymetric survey by an echo sounder, (2) survey of submarine geology using an acoustic probe, (3) observation of nearshore current systems using floats, (4) documentation of the transport pattern of suspended sediment by aerial photographs, (5) examination of depositional environments of bottom and beach material by sieve analysis, (6) inference of long-term alongshore sediment transport pattern from the grain size properties of beach sand, and measurement of short-term trends by use of fluorescent sand, and (7) examination of long-term shoreline change using old and recent maps.

scholarly journals Storm Driven Migration of the Napatree Barrier, Rhode Island, USA

Geosciences ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 330
Author(s):  
Bryan A. Oakley
Keyword(s):  
Rhode Island ◽  
Shoreline Change ◽  
Aerial Photographs ◽  
Tropical Storms ◽  
Lower Intensity ◽  
Storm Activity ◽  
The Impact ◽  
Washover Fan

Napatree Point, an isolated barrier in southern Rhode Island, provides a case study of barrier spit migration via storm driven overwash and washover fan migration. Documented shoreline changes using historical surveys and vertical aerial photographs show that the barrier had little in the way of net change in position between 1883 and 1939, including the impact of the 1938 hurricane. The barrier retreated rapidly between 1945 and 1975, driven by both tropical and extra-tropical storms. The shoreline position has been largely static since 1975. The removal of the foredune during the 1938 hurricane facilitated landward shoreline migration in subsequent lower intensity storms. Dune recovery following the 1962 Ash Wednesday storm has been allowed due to limited overwash and barrier migration over the last several decades. Shoreline change rates during the period from 1945–1975 were more than double the rate of shoreline change between 1939 and 2014 and triple the rate between 1883 and 2014, exceeding the positional uncertainty of these shoreline pairs. The long-term shoreline change rates used to calculate coastal setbacks in Rhode Island likely underestimate the potential for rapid shoreline retreat over shorter time periods, particularly in a cluster of storm activity. While sea-level rise has increased since 1975, the barrier has not migrated, highlighting the importance of storms in barrier migration.

scholarly journals SIMULATION OF LONG-TERM SHORELINE CHANGE DRIVEN BY LONGSHORE AND CROSS-SHORE SEDIMENT TRANSPORT

2020 ◽  
pp. 31
Author(s):  
Yan Ding ◽  
Sung-Chan Kim ◽  
Richard B. Styles ◽  
Rusty L. Permenter
Keyword(s):  
Sediment Transport ◽  
Shoreline Change ◽  
Breaking Wave ◽  
Beach Profile ◽  
Shoreline Evolution ◽  
Longshore Sediment Transport ◽  
Wave Energy Flux ◽  
Semi Empirical ◽  
Evolution Modeling

Driven by wave and current, sediment transport alongshore and cross-shore induces shoreline changes in coasts. Estimated by breaking wave energy flux, longshore sediment transport in littoral zone has been studied for decades. Cross-shore sediment transport can be significant in a gentle-slope beach and a barred coast due to bar migration. Short-term beach profile evolution (typically for a few days or weeks) has been successfully simulated by reconstructing nonlinear wave shape in nearshore zone (e.g. Hsu et al 2006, Fernandez-Mora et al. 2015). However, it is still lack of knowledge on the relationship between cross-shore sediment transport and long-term shoreline evolution. Based on the methodology of beach profile evolution modeling, a semi-empirical closure model is developed for estimating phase-average net cross-shore sediment transport rate induced by waves, currents, and gravity. This model has been implemented into GenCade, the USACE shoreline evolution model.

scholarly journals Rapid retreat of permafrost coastline observed with aerial drone photogrammetry

2019 ◽  
Vol 13 (5) ◽  
pp. 1513-1528 ◽  
Author(s):  
Andrew M. Cunliffe ◽  
George Tanski ◽  
Boris Radosavljevic ◽  
William F. Palmer ◽  
Torsten Sachs ◽  
...  
Keyword(s):  
Coastal Erosion ◽  
Average Rate ◽  
Temporal Frequency ◽  
Shoreline Change ◽  
Yukon Territory ◽  
Aerial Photographs ◽  
The Arctic ◽  
Storm Events ◽  
Short Term

Abstract. Permafrost landscapes are changing around the Arctic in response to climate warming, with coastal erosion being one of the most prominent and hazardous features. Using drone platforms, satellite images, and historic aerial photographs, we observed the rapid retreat of a permafrost coastline on Qikiqtaruk – Herschel Island, Yukon Territory, in the Canadian Beaufort Sea. This coastline is adjacent to a gravel spit accommodating several culturally significant sites and is the logistical base for the Qikiqtaruk – Herschel Island Territorial Park operations. In this study we sought to (i) assess short-term coastal erosion dynamics over fine temporal resolution, (ii) evaluate short-term shoreline change in the context of long-term observations, and (iii) demonstrate the potential of low-cost lightweight unmanned aerial vehicles (“drones”) to inform coastline studies and management decisions. We resurveyed a 500 m permafrost coastal reach at high temporal frequency (seven surveys over 40 d in 2017). Intra-seasonal shoreline changes were related to meteorological and oceanographic variables to understand controls on intra-seasonal erosion patterns. To put our short-term observations into historical context, we combined our analysis of shoreline positions in 2016 and 2017 with historical observations from 1952, 1970, 2000, and 2011. In just the summer of 2017, we observed coastal retreat of 14.5 m, more than 6 times faster than the long-term average rate of 2.2±0.1 m a−1 (1952–2017). Coastline retreat rates exceeded 1.0±0.1 m d−1 over a single 4 d period. Over 40 d, we estimated removal of ca. 0.96 m3 m−1 d−1. These findings highlight the episodic nature of shoreline change and the important role of storm events, which are poorly understood along permafrost coastlines. We found drone surveys combined with image-based modelling yield fine spatial resolution and accurately geolocated observations that are highly suitable to observe intra-seasonal erosion dynamics in rapidly changing Arctic landscapes.

scholarly journals EXPERIMENTAL INVESTIGATION ON DYNAMIC EQUILIBRIUM BAY SHAPE

2012 ◽  
Vol 1 (33) ◽  
pp. 37
Author(s):  
Sutat Weesakul ◽  
Somruthai Tasaduak
Keyword(s):  
Experimental Investigation ◽  
Sediment Transport ◽  
Dynamic Equilibrium ◽  
Shoreline Change ◽  
Sediment Supply ◽  
Coastal Protection ◽  
Supply Source ◽  
Wave Condition ◽  
Longshore Sediment Transport

Equilibrium bay is a bay that its shoreline is stable and does not change with time in long term. This concept can be applied for coastal protection. Experiments on dynamic equilibrium bay planform are conducted in a laboratory. There is one location of sediment supply source into a bay near upcoast headland and its magnitude vary from case to case. Wave obliquity varies from small to moderate values. These are two main parameters while wave condition is kept constant. The final bay planforms are investigated and recorded once they reach equilibrium with condition that sediment transport gradient approaches zero and no further shoreline change are observed. The parabolic equation similar to that for static equilibrium is newly proposed. The coefficients are originally derived and found to be a function of wave obliquity and the ratio of sediment supplied into bay to longshore sediment transport. The new dynamic equilibrium bay equation can be used and applied to study morphology change with variation of supplied sediment from inland.

scholarly journals VIRGINIA BEACH SAND SIZE AS BASIS FOR DESIGN OF ON-SHORE DREDGED MATERIAL DISPOSA

1986 ◽  
Vol 1 (20) ◽  
pp. 84
Author(s):  
Cyril Galvin ◽  
James W. Holton ◽  
Ronald G. Vann
Keyword(s):  
Atlantic Ocean ◽  
Shoreline Change ◽  
Beach Sand ◽  
Dredged Material ◽  
Virginia Beach ◽  
Median Diameter ◽  
Northern Segment ◽  
Ocean Shore ◽  
Sand Size

Analyses of sand samples collected along and across the Atlantic Ocean shore of Virginia Beach, Virginia, suggest that sand placed on the shore should have a minimum median diameter of 0.20 mm to efficiently benefit the beach. Size analyses and shoreline change data show that the existing long-term beach replenishment by mechanical bypassing across Rudee Inlet and by truck-hauled sand from land sources is effective and necessary to maintain the shore along the commercial segment of Virginia Beach. The data also indicate that the northern segment of Virginia Beach shore, occupying more than half the distance between Rudee Inlet and Fort Story, is gaining sand. About two million cubic meters of sand to be dredged from the Atlantic Ocean Channel offshore of Virginia Beach will be suitable for placement on the beach.

scholarly journals Grain size variability as an indicator of sediment transport alongshore the Curonian Spit (south-eastern Baltic Sea)

Baltica ◽  
2016 ◽  
Vol 29 (2) ◽  
pp. 145-155 ◽  
Author(s):  
Olga Kovaleva ◽  
Boris Chubarenko ◽  
Donatas Pupienis
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Sampling Period ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Curonian Spit ◽  
Size Variability ◽  
Alongshore Sediment Transport ◽  
Calm Weather

Sediment samples have been collected along the sea coast of the Curonian Spit in summer season of 2011, 2014 and 2015-years. According to grain size analysis the shoreline and the berm consist of well and very well-sorted sand, medium-sized on the southern (Russian) part of the spit, medium and fine on the northern (Lithuanian) part. ‘McLaren’ method was applied to determine the long-shore sediment transport directions. Mismatch of results with those obtained by methods based on simulation of resulted wave action did not prove the hypothesis that ‘McLaren’ method was able to reveal long-term resulted sediment transport. The hypothesis that ‘McLaren’ method indicates the directions of alongshore sediment transport during the stormy conditions preceding the sampling period was not proved also. It was concluded that application of ‘McLaren’ method in respect of the Curonian Spit shore, which is a transit one without permanent sources or sinks of sediments, is not efficient. ‘McLaren’ method was applied to describe the cross-shore sediment movement. It was found that deposits from the trough (located between the bar and shoreline) are transported to the shoreline that is in a line with the known fact about cross-shore transport of bottom material during the calm weather.

scholarly journals Analysis of Shoreline Change along Cape Coast-Sekondi Coast, Ghana

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Ishmael Yaw Dadson ◽  
Alex Barimah Owusu ◽  
Osman Adams
Keyword(s):  
Satellite Image ◽  
Shoreline Change ◽  
Aerial Photographs ◽  
Cape Coast ◽  
Change Analysis ◽  
Community Interactions ◽  
Erosion And Accretion ◽  
End Point Rate

The two most important factors constantly impinging on the net movement of shorelines are erosion and accretion. This study analyzed the role of erosion and accretion in shoreline changes along the coast between Cape Coast and Sekondi in the central and western regions of Ghana, respectively. Aerial photographs, satellite images, and topographical maps were used. In addition, field survey using Global Positioning System (GPS) was conducted at selected locations due to the unavailability of satellite image for 2013. Shoreline change analysis was conducted using Digital Shoreline Analysis Systems based on End Point Rate formula. In addition, community interactions were also conducted to get first-hand information from the local inhabitants. The study finds that the shoreline under study has been fluctuating. The sea advanced inland between 1972 and 2005, which is attributed mainly to intense erosion. The study further reveals that, in the past five years, the shoreline had been retreating mainly due to increased accretion. It is recommended that the shoreline under study should be monitored regularly to keep abreast with net movements that will occur in either the short term or the long term so as to factor the net effect into the management of the coastal zone.

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