Rubén A. Medina, Andrea L. Martínez, Liliana Mormeneo y Sebastián M. Richiano
2 016
Rev. Asoc. Geol. Argent. vol.73 no.2 Buenos Aires jun. 2016
Se dan a conocer los diversos cambios morfosedimentarios que se produjeron en un sector de costa ubicado al norte de un espigón construido en Camet Norte (Buenos Aires) a fines del año 2011. Durante el período analizado (julio 2011-diciembre 2015) se observó en un punto de control ubicado a 200 m al norte de la estructura, aguas abajo respecto a la deriva litoral, que el nivel de arena en playa rara vez fue superior al valor registrado en julio de 2011, cuatro meses antes de la construcción de la obra. Lo contrario sucedió con otros tres puntos de control distantes a más de 1.275 m del nuevo espigón, en donde rara vez el nivel de arena fue inferior al observado en esa fecha (julio 2011). A su vez, a lo largo del año la granulometría de la arena correspondiente a la playa frontal del área monitoreada cercana a la obra, por lo general fue más gruesa respecto a los restantes puntos de control, indicando posiblemente una mayor energía de ola en ese sector de costa. El menor nivel de arena asociado a una mayor energía de ola en el sector próximo a la estructura, permitió probablemente la afluencia directa del embate de las mismas durante todo el período, reflejándose esto en un mayor retroceso del acantilado y sobre todo del microacantilado, con un total de 96 y 350 cm (22 y 79 cm/año), respectivamente. Estos retrocesos están asociados preferentemente a eventos de corta duración correspondientes a tormentas marítimas denominadas localmente "sudestadas".
Morphosedimentary changes caused by the construction of a groin in Camet Norte, Buenos Aires province, Argentina
Our study shows several morphodynamic changes occurred along a coastal sector downstream of a groin built at Camet Norte locality (Buenos Aires province) by the end of 2011. During the time span analyzed (July 2011-December 2015), at a control site located 200 m north of the structure, downstream relative to the littoral drift, it was possible to observe that the sand level on the beach was seldom higher than that recorded in July 2011, four months before the groin was built. The opposite occurred in other three control sites placed more than 1,275 m far from the new groin, where the sand level was seldom lower than that observed in July 2011. In addition, along the whole year, the size of the sandy particles of the foreshore in the area localized near the structure was generally higher than that of the remaining control sites, suggesting stronger wave energy within the corresponding coastal sector. Most probably, within control site localized next to groin coastal sector a lower sandy level together with stronger wave energy allowed a direct influx and effect of the waves during the whole time span. This is reflected by a stronger retreat of the main cliff and especially the microcliff, with a total of 96 and 350 cm (22 and 79 cm/year), respectively. These retreats are linked mainly to short marine events locally known as "sudestadas".
Our study shows several morphodynamic changes occurred along a coastal sector downstream of a groin built at Camet Norte locality (Buenos Aires province) by the end of 2011. During the time span analyzed (July 2011-December 2015), at a control site located 200 m north of the structure, downstream relative to the littoral drift, it was possible to observe that the sand level on the beach was seldom higher than that recorded in July 2011, four months before the groin was built. The opposite occurred in other three control sites placed more than 1,275 m far from the new groin, where the sand level was seldom lower than that observed in July 2011. In addition, along the whole year, the size of the sandy particles of the foreshore in the area localized near the structure was generally higher than that of the remaining control sites, suggesting stronger wave energy within the corresponding coastal sector. Most probably, within control site localized next to groin coastal sector a lower sandy level together with stronger wave energy allowed a direct influx and effect of the waves during the whole time span. This is reflected by a stronger retreat of the main cliff and especially the microcliff, with a total of 96 and 350 cm (22 and 79 cm/year), respectively. These retreats are linked mainly to short marine events locally known as "sudestadas".
http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S0004-48222016000200009#fig5