Analysis of Shoreline Changes in Ikoli River in Niger Delta Region Yenagoa, Bayelsa State Using Digital Shoreline Analysis System (DSAS)

The use of Digital Shoreline Analysis System was used to determine shoreline changes in Ikoli River, Yenagoa, Bayelsa State. Shoreline data were extracted from satellite imagery over thirty years (1991-2021). The basis of this study is to use Digital Shoreline Analysis System to determine erosion and accretion areas. The result reveals that the average erosion rate in the study area is 1.16 m/year and the accretion rate is 1.62 m/year along the Ikoli River in Ogbogoro Community in Yenagoa, Bayelsa State. The mean shoreline length is 5.24 km with a baseline length of 5.2 km and the area is classified into four zones to delineate properly area of erosion and accretion based on the five class of Linear regression rate, endpoint rate and weighted linear rate of which zone I contain very high erosion and high erosion with an area of landmass 255449.93 m2 of 38%, zone II contain moderate accretion, very high accretion and high accretion with a land area of 1666816.46 m2 with 24%, zone III has very high erosion and high erosion with an area of landmass 241610.85 m2 of 34 % and zone IV contain moderate accretion and high accretion with land area 30888.08 m2 with 4%. Out of the four zones, zone I and II were found to be eroding with 72% and zone II and IV contain accretion with 28%. The result shows that 44% of the area have been eroded. Therefore, coastal engineers, planners, and shoreline zone management authorities can use DSAS to create more appropriate management plans and regulations for coastal zones and other coastal parts of the state with similar geographic features.

Monitoring of Recovery Process at Yeongildae Beach, South Korea, Using a Video System

Once a beach is eroded by storm waves, it is generally recovered under milder wave conditions. To prevent or reduce damage, it is therefore important to understand the characteristics of the site-specific recovery process. Here, we present the results, based on a data set from a video monitoring system and wave measurements, of the recovery process in a pocketed beach located inside a bay where the shoreline retreated harshly (~12 m, on average, of beach width) during Typhoon TAPAH (T1917) in September 2019. It took about 1.5 years for the beach to be recovered to the level before the typhoon. During this period, the erosion and accretion were repeated, with the pattern highly related to the wave power (Pw); most of the erosion occurred when Pw became greater than 30 kWatt/m, whereas the accretion prevailed when Pw was no greater than 10 kWatt/m. The recovery pattern showed discrepancies between different parts of the beach. The erosion during storm events was most severe in the southern part, whereas the northern shoreline did not significantly change even during TAPAH (T1917). In contrast, the recovery process occurred almost equally at all locations. This discrepancy in the erosion/accretion process was likely due to human intervention, as a shadow zone was formed in the northern end due to the breakwaters, causing disequilibrium in the sediment transport gradient along the shore. The results in this study could be applied in designing the protection plans from severe wave attacks by effectively estimating the size of coastal structures and by correctly arranging the horizontal placement of such interventions or beach nourishment. Although the application of these results should be confined to this specific site, the method using wave energy parameters as criteria can be considered in other areas with similar environments, for future planning of beach protection.

Analysis of shoreline changes along the coast of Tiruvallur district, Tamil Nadu, India

Shoreline change is considered as one of the most dynamic process, which was mapped along the coast of Tiruvallur district by using topographic maps of 1976 and multi-temporal satellite images. The satellite images were pertaining to 1988, 1991, 2006, 2010, 2013 and 2016 which were used to extract the shorelines. It is important to map and monitor the HTL (High Tide line) at frequent time interval as it considered as shoreline, which was demarcated by using visual interpretation technique from satellite images and topographic maps. Followed by this, an overlay analysis was performed to calculate areas of erosion and accretion in the study area. The results revealed that the coast of Tiruvallur district lost 603 ha and gained 630 ha due to erosion and accretion respectively. It was confirmed after the ground truth survey carried out in the study area. The high accretion of 178 ha was found nearby Pulicat Lake and low accretion of 19 ha seen between Pulicat lake to Kattupali port. The high erosion area was found along the Pulicat lake, Kattupali and Ennore ports, and Ennore creek mouth and south of Ennore such as Periya Kuppam, Chinna Kuppam, Kasi Koil Kuppam, and Thyagarajapuram. It may be concluded that the main causes of coastal erosion and accretion in the study area are anthropogenic and natural factors, which alter the coastal environment.

Analysis of shoreline changes along the coast of Tiruvallur district, Tamil Nadu, India

Shore line change is considered as one of the most dynamic processes, which were mapped along the coast of Tiruvallur district by using topographic maps of 1976 and multi-temporal satellite images. The satellite images pertaining to 1988, 1991, 2006, 2010, 2013 and 2016 were used to extract the shorelines. It is important to map and monitor the HTL (High Tide Line) at frequent time intervals as the shoreline was demarcated by using visual interpretation technique from satellite images and topographic maps. Followed by this, an overlay analysis was performed to calculate areas of erosion and accretion in the study area. The results revealed that the coast of Tiruvallur district lost 603 ha and gained 630 ha due to erosion and accretion respectively. It was confirmed after the ground truth survey carried out in the study area. The high accretion of 178 ha was found nearby Pulicat Lake and low accretion of 19 ha was seen between Pulicat Lake and Kattupali Port. The high erosion area was found along the Pulicat Lake, Kattupali and Ennore ports, and Ennore creek mouth and southern Ennore such as Periya Kuppam, Chinna Kuppam, Kasi Koil Kuppam, and Thyagarajapuram. It may be concluded that the coastal erosion and accretion in the study area were mainly caused by anthropogenic and natural factors, which altered the coastal environment.

Evaluation of hydromorphological conditions of Grand Popo Beach using two unique video cameras

Beaches are characterized by complex spatial and temporal patterns of erosion and accretion subjected to significant wave and tide influence. The objective of this study is to estimate the evolution of hydromorphodynamic conditions on the shoreline of Grand Popo Beach observed from two adjacent video camera setups. We have analyzed the impact of the variability of hydrodynamic parameters on the beach evolution and evaluated the variabilities of the hydrodynamic and morphologic parameters from the two cameras. Despite the nonhomogeneity within the cameras’ intrinsic properties, the various results obtained from the two systems indicate that wave conditions (peak period and significant height) from the cameras have the same variations, whereas the shoreline variations of camera A are not the same as those of camera B. It is generally during the summer that the Grand Popo Beach is exposed to an agitated environment with strong observed values of significant wave heights and wave energy flux, undoubtedly resulting in significant sediment transport along the beach leading a shoreline retreat. The results indicate that in 3.5 years the shoreline of Grand Popo Beach has retreated by 10 m.

Subaerial beach morphology change from multiple storms during the 2020 hurricane season

Frequent or consecutive storms impacting coastal areas can result in unexpected or variable impacts. This study evaluates spatiotemporal variability and cumulative impacts on the subaerial beach from four major tropical storms of varying intensity and proximity impacting the study area of Palm Beach County, Florida, during the 2020 Atlantic Basin Hurricane season. Impacts from Hurricanes Isaias, Laura, Sally, and Teddy were measured using Real-Time Kinematic Global Positioning System (RTK GPS) at 14 transects throughout the northern and southern portion of the county. Alongshore morphologic variability resulted from each storm, with some expected patterns of erosion and accretion with a few unexpected impacts. The first three storms caused swash or collision regime impacts on the Sallenger scale. Hurricane Teddy was the fourth storm to impact the study area, causing overwash at numerous locations. Whereas the first two storms of the season caused mostly erosion of the subaerial beach, the southeasterly approach of Hurricane Sally reversed the cumulative volume loss trend in the northern portion of the study area with accretion. Hurricane Teddy was the most distant storm but occurred at the highest tide and produced the largest waves and highest winds. The most variable patterns in erosion and accretion resulted from Hurricane Teddy, which also dominated the overall (or cumulative) volume and contour change. Further study is recommended for a multi-storm season that includes the subaqueous portion of the beach profile to elucidate trends of cross-shore and alongshore drivers of storm-induced morphology change.