Shoreline Change Analysis along the Udupi-Dakshina Kannada Coastal Stretch in Karnataka, West Coast of India using DSAS

Study of morphological variations and the effects of oceanographic processes such as erosion and accretion at different temporal scales are important to understand the nature of the coast and the cyclic changes occurring during different seasons. The Udupi-Dakshina Kannada coast along the west coast of India exhibits a wide range of changes depending on the interactions of tide and wave energy, sediment supply and more importantly human intervention. In view of this, the present work has been carried out to study the changes in shoreline changes along the Udupi-Dakshina Kannada coast over a period of 29 years from 1990 to 2019. Remote Sensing and GIS techniques have been used to demarcate shorelines and calculate the shoreline change rates. Overall accretion and erosion rates were found to be 1.28 m/year and 0.91 m/year respectively along the coast. Highest accretion and erosion rates of 12.57 m/year and 5.34 m/year was noticed along the Dakshina Kannada coast. The study also suggests that multi-dated satellite data along with statistical techniques can be effectively used for prediction of shoreline changes. Keywords: remote sensing, GIS, Dakshina Kannada coast, oceanography, shoreline.

Comparison of Mangrove Stand Development on Accretion and Erosion Sites in Ca Mau, Vietnam

Mangroves are adapted to coastal processes; however, mangrove species showed various responses to estuarian environments, leading to different structural characteristics at accretion and erosion areas. The species composition, structure and regeneration of mangrove forests were investigated to provide insight into mangrove forest development in response to shoreline accretion and erosion processes. The species composition and stand structure of mangrove forests were measured along the distance from the shoreline at accretion and erosion sites in Ca Mau, Vietnam. The hierarchical clustering of grouped stands based on species composition and tree size distribution was conducted. Grouped mangrove stands showed landward changes in species composition and stand structure from the shoreline (p < 0.05), reflecting the timescale of accretion or erosion at both accretion and erosion sites. Stand development patterns differed between accretion and erosion sites, and Avicennia alba and Rhizophora apiculata dominated seaward plots at accretion and erosion sites, respectively. Newer accredited sites were dominated by A. alba. Mangrove stands developed from dense A. alba dominant to R. apiculata dominant stands with increasing tree size at accretion sites. There were more species-colonized sites with a higher erosion rate or that were more recently eroded, implying that timescale of erosion and erosion rate affected species composition and regeneration on erosion sites. Accretion and erosion affected stand development of mangroves differently, implying that conservation and restoration strategies should be applied differently to accretion and erosion sites.

Variação da linha de costa no litoral cearense (1984-2018)

A erosão costeira ocorre em várias partes do mundo. Ela, por vezes, destrói equipamentos e casas próximas da linha de costa causando prejuízos econômicos. No Estado do Ceará existem trechos que estão retrogradando, exemplo clássico é da área próxima do Porto do Mucuripe (Fortaleza). Diante do exposto, o objetivo deste estudo foi analisar a evolução da linha de costa de todo o Estado do Ceará, dentro da escala temporal de 1984 a 2018. Para alcançar esse objetivo foram realizados o processamento digital de imagens de satélite, confecção de mapas de variação da linha de costa e quantificação das áreas de progradação e retrogradação. Em termos matemáticos, na zona costeira do Ceará houve equilíbrio dinâmico entre os processos de acreção e erosão, contudo, existem alguns hotspots de erosão nos diferentes setores do litoral. Há a necessidade de monitoramento contínuo da zona costeira em diferentes escalas espaciais e temporais para melhor compreensão do comportamento costeiro, bem como políticas que inibam a ocupação deletéria a essa região. Shoreline variation in Ceará coastal zone (1984-2018) A B S T R A C TCoastal erosion occurs in several parts of the world. Sometimes, it destroys structures close to the shoreline causing economic damage. In the state of Ceará, Brazil, there are stretches with retrogradation. A classic example is from the area near the Mucuripe harbor (Fortaleza). From this context, the objective of this paper was to analyze the evolution of the State of Ceará shoreline between 1984 and 2018. To achieve this objective, the digital processing of satellite images was performed, developing maps of shoreline variation and quantification of progradation and retrogradation areas. In mathematical terms, at the coastal zone of Ceará there was a dynamic balance between the processes of accretion and erosion. However, there are some erosion hotspots in different sectors of the state shoreline. There is a need for continuous monitoring of the coastal zone in different spatial and temporal scales to better understand coastal behavior, as well as policies that inhibit the deleterious occupation of this region.Keywords: Coastal zone; Monitoring; Coastal Erosion.