LAYOUT DESIGN OF COASTAL STRUCTURES FOR MITIGATING BEACH EROSION

Author(s):  
JUNG L. LEE ◽  
SAHONG LEE ◽  
TAE-KON KIM ◽  
WON CHUL CHO
1986 ◽  
Vol 1 (20) ◽  
pp. 171 ◽  
Author(s):  
T. Uda ◽  
M. Sumiya ◽  
Y. Kobayashi

The coast of Ibaraki Prefecture, facing the Pacific Ocean, has an alongshore stretch of 181 km. On this coast many structures associated with harbors have been constructed since early 1960s. Since then 25 years have passed, and some notable beach changes due to the influence of the construction of the coastal structures have been observed. This study aims to examine the actual situation of the beach change around large-scale structures and the damages of the coastal structures selecting the coast of Ibaraki Prefecture as the study area. For the purpose aerial photographs were taken along the coast, and the topographic surveys and measurements of median diameter of beach-face materials were made. Data of the soundings having been conducted once a year since 1975 around Oharai Port and Hazaki Fishery Harbor were collected in order to study the beach changes around the large-scale coastal structures. For the analysis of these data the comparison of the shoreline changes were performed by using four sets of aerial photographs since 1947 to the present. Moreover, temporal and spatial changes of the beach topography were investigated by the sounding data.


2012 ◽  
Vol 1 (33) ◽  
pp. 125 ◽  
Author(s):  
María Alejandra Lira-Pantoja ◽  
Alec Torres-Freyermuth ◽  
Christian Mario Appendini ◽  
Diana Carolina Fernández ◽  
Paulo Salles ◽  
...  

The Yucatan coastline has been experiencing beach erosion during the past few decades; the erosion has reached critical points at some locations such as the Chelem beach, located near the Progreso Pier. Despite this problem, only few studies have been devoted in order to investigate the role of coastal structures on explaining the high erosion rates reported at this location. Therefore, the aim of this work is to evaluate the effects of the Progreso Pier on the wave transformation and alongshore sediment transport in the study area. Field surveys were conducted in a monthly basis in order to estimate the erosion rates and wave conditions with an ADCP installed at 8 m water depth. The field information confirmed the high erosional trends (O(1)m/year) that explain coastal infrastructure damage and property losses. The wave measurements were employed as the forcing of a wind-wave numerical model (MIKE 21 SW). The numerical model is implemented in the study area for two different scenarios, with and without the pier; this was to estimate nearshore wave conditions. Subsequently, the nearshore wave climate at 5 m water depth is employed for the calculation of alongshore sediment transport rates in 5 points that are representative of the littoral drift along the study area. The modeling results show that the pier acts as a large scale wave-sheltering structure that induces important alongshore sediment transport gradients under mean wave conditions, decreasing the capacity of the waves to recover the beach. On the other hand, during winter storms, when the direction of the waves is from the NNW, the structure does not seem to play an important role on wave transformation into the study. As a result, the Progreso Pier enhances beach erosion in the Chelem area by inducing algonshore gradients in sediment transport and decreasing the beach recovery capability


Author(s):  
Evgenii Burnashov ◽  
Evgenii Burnashov ◽  
Konstantin Karmanov ◽  
Konstantin Karmanov

The study gives quantitative estimation of natural landforms sensitivity of accumulative type coasts exposed to human influence. Foredune is an essential element of a morphological structure of thebarrier spits located at the Baltic Sea sand coasts. The study compares contribution of the beach erosion and deflation (soil drifting) to the foredune degradation on the sea shore of the barrier spit with or without the recreational impact. The analysis is performed for three typical polygons located on the Russian part of the Vistula Spit. Chosen polygons present shore segments with various intensity of tourism: visitors from the village, unregulated camp tourism, and nearly natural conditions. Detailed geodesic survey was carried out on these three polygons (length 515 m, 265 m, and 521 m respectively; total area – 125000 m2) in July of 2015. It was done with single-frequency geodesic GPS Trimble 5700L1 (base station) and TrimbleR3 (rover). Two DEMs were developed using the results of laser scanning of 2007 and the survey of 2015. Volume deformation for whole polygons and its particular parts (beach and foredune ridge) was made by comparison of the DEMs. In the case of touristic load the effect of deflation is 5-15 times higher than the marine erosion of foredune edge. If not affected by an anthropogenic factor the foredune erosion is caused mainly by the sea, and its impact is 6 times higher than that of the natural deflation.


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