Identificación de factores físicos que rigen los procesos erosivo-acumulativos en playas de la Costa Sur de Cuba
Archivos
Fecha
2017-07-10
Autores
Sotolongo Hernández, Eliecer
Título de la revista
ISSN de la revista
Título del volumen
Editor
Universidad Central “Marta Abreu” de Las Villas
Resumen
Los objetivos en este trabajo son identificar y aplicar los principales factores físicos que rigen los procesos erosivo-acumulativos en las playas y determinar la magnitud de erosión - acumulación y la variación de la línea de costa durante un determinado período de tiempo. Para esto se realizan mediciones granulométricas y se analizan los resultados de mediciones de perfiles topográficos perpendiculares a la línea de costa en Rancho Luna y Playa Fría, dichos resultados se comparan para un período de 6 y 5 años respectivamente para describir la tendencia de la playa a mediano plazo. Se tomaron cinco muestras de sedimento en ambas playas y se levantaron siete perfiles en playa Rancho Luna y nueve perfiles en Playa Fría que fueron medidos en un espacio de tres meses, estos resultados se comparan y se calculan las pérdidas o ganancias de arena y el avance o retroceso de la línea de costa.
Entre los resultados está que la arena en ambas playas es de granulometría fina-media, su composición es biogénica en un 85.72 % y mineral en un 14.28 % para Playa Fría, y en Rancho Luna es un 63,32 % biogénica y mineral en un 36,68 %. Además se demuestra la existencia de erosión en ambas playas así como de retroceso de la línea de costa. Los principales factores físicos que rigen los procesos erosivo-acumulativos en ambas playas son el oleaje y el viento. Playa Fría tiene mayor retroceso y erosión en sus extremos, perfiles 1, 2, 3 y 5, siendo prácticamente acumulativa o en equilibrio hacia el centro, perfil 4. El resultado de los cálculos en Playa Fría en 5 años muestra un valor de -1803.98 m3 de pérdida absoluta de arena. El valor de retroceso de la costa determinado es de 2,5 m por año. Mientras que el promedio espacial de retroceso para toda la playa hallado en el intervalo de 2012-2017 es de -12.846 m y el promedio espacial de erosión para toda la playa hallado para el intervalo de 2012-2017 es de -10.023 m.
En Rancho Luna se aprecia un desplazamiento hacia tierra de la topografía de la playa en los perfiles del 2 al 4 con erosión y retroceso de la línea de costa, pero sin cambiar la forma del perfil. En el perfil 5 se observa retroceso de línea de costa pero no desplazamiento de todo el perfil hacia tierra. El promedio espacial de retroceso para toda la playa hallado en el intervalo de 2011-2017 es de -1.47 m. Mientras que el promedio espacial de erosión para toda la playa hallado para el intervalo de 2011-2017 es de -22.8 m. El valor de retroceso de la costa determinado es de 0,24 m por año y el promedio del volumen de arena perdida en los seis años de -5438.2 m3 mostrando un marcado desbalance en cuanto a la entrada o salida de sedimentos a la playa.
The objectives in this work are to identify the main physical factors that govern erosive-cumulative processes in the beaches and to determine the magnitude of erosion - accumulation and the variation of the coastline during a certain period of time. For this, sizing measurements are made and the results of measurements of topographic profiles perpendicular to the coast line in Rancho Luna and Playa Fría are analyzed, these results are compared for a period of 6 and 5 years respectively to describe the trend of the beach to medium term. Five sediment samples were taken at both beaches and seven profiles were raised at Rancho Luna beach and nine profiles at Playa Fría were measured in a space of three months, these results are compared and sand losses and gains are calculated and progress or receding the coastline. Among the results obtained we have that the sand in both beaches is of fine-medium granulometry, its composition is biogenic in 85.72% and mineral in 14.28% for Playa Fría, and Rancho Luna is 63.32% biogenic and mineral in A 36.68%. In addition it is demonstrated the existence of erosion in both beaches as well as of coastline recoil. The main physical factors that govern erosive-cumulative processes on both beaches are swell and wind. Playa Fría has greater recoil and erosion at its extremes, profiles 1,2,3 and 5, being practically cumulative or in equilibrium towards the center, profile 4. The result of the calculations in Playa Fria in 5 years shows a value of -1803.98 M3 of absolute sand loss. The setback value of the determined coast is 2.5 m per year. While the spatial average recoil for the entire beach found in the range of 2012-2017 is -12,846 m and the spatial mean of erosion for the entire beach found for the range of 2012-2017 is -10,023 m. In Rancho Luna, there is a displacement towards the topography of the beach in the profiles from 2 to 4 with erosion and regression of the coastline, but without changing the shape of the profile. Profile 5 shows a recess of coastline but not displacement of the entire profile towards land. The spatial average of recoil for the whole beach found in the interval of 2011-2017 is -1.47 m. While the spatial mean of erosion for the entire beach found for the 2011-2017 range is -22.8 m. The setback value of the determined coast is 0.24 m per year and the average volume of sand lost in the six years of -5438.2 m3 showing a marked imbalance in the entry or exit of sediments to the beach.
The objectives in this work are to identify the main physical factors that govern erosive-cumulative processes in the beaches and to determine the magnitude of erosion - accumulation and the variation of the coastline during a certain period of time. For this, sizing measurements are made and the results of measurements of topographic profiles perpendicular to the coast line in Rancho Luna and Playa Fría are analyzed, these results are compared for a period of 6 and 5 years respectively to describe the trend of the beach to medium term. Five sediment samples were taken at both beaches and seven profiles were raised at Rancho Luna beach and nine profiles at Playa Fría were measured in a space of three months, these results are compared and sand losses and gains are calculated and progress or receding the coastline. Among the results obtained we have that the sand in both beaches is of fine-medium granulometry, its composition is biogenic in 85.72% and mineral in 14.28% for Playa Fría, and Rancho Luna is 63.32% biogenic and mineral in A 36.68%. In addition it is demonstrated the existence of erosion in both beaches as well as of coastline recoil. The main physical factors that govern erosive-cumulative processes on both beaches are swell and wind. Playa Fría has greater recoil and erosion at its extremes, profiles 1,2,3 and 5, being practically cumulative or in equilibrium towards the center, profile 4. The result of the calculations in Playa Fria in 5 years shows a value of -1803.98 M3 of absolute sand loss. The setback value of the determined coast is 2.5 m per year. While the spatial average recoil for the entire beach found in the range of 2012-2017 is -12,846 m and the spatial mean of erosion for the entire beach found for the range of 2012-2017 is -10,023 m. In Rancho Luna, there is a displacement towards the topography of the beach in the profiles from 2 to 4 with erosion and regression of the coastline, but without changing the shape of the profile. Profile 5 shows a recess of coastline but not displacement of the entire profile towards land. The spatial average of recoil for the whole beach found in the interval of 2011-2017 is -1.47 m. While the spatial mean of erosion for the entire beach found for the 2011-2017 range is -22.8 m. The setback value of the determined coast is 0.24 m per year and the average volume of sand lost in the six years of -5438.2 m3 showing a marked imbalance in the entry or exit of sediments to the beach.
Descripción
Palabras clave
Playa, Erosión, Acumulación, Granulometría, Factores Físicos, Beach, Erosion, Accretion, Granulometry, Physical Factors