Dinamismo, complejidad y especificidad de los litorales estuarinos: análisis de la dinámica litoral en Punta Atalaya, Buenos Aires, Argentina

Abstract

Littorals are complex and dynamic spaces, as a result of the interaction between natural dynamics and social assessments over time. This interaction triggers multiple processes, which lend specificity to their coasts. Intertidal environments called marshes are developed in estuarine littorals, which have been intensely modified in large urban metropolises. These environments dynamics have been extensively studied in the northern hemisphere, but scarce research has been performed in the southern hemisphere. In the present work a multitemporal study of a recent developed marsh is done in the coast of Punta Atalaya (district of Magdalena, Buenos Aires, Argentina), located along the intermediate sector of the Argentine coast of the Río de la Plata estuary, using the coastline as an indicator, considering it as the outer limit of this environment. The study was based on its identification in aerial photographs and high-resolution satellite images during the 1929-2016 period. Using specialized software for the multi-temporal change analysis, field work and general and specific bibliography review, an explanatory approximation of the littoral dynamics of this territory was performed. It was determined that the coast of Punta Atalaya presents an accretional tendency during the last century, although changes in the temporal and spatial micro scale are detected throughout the period, responding to accretional and erosive dynamics that derive from the interaction of biological, sedimentary, meteorological and social processes. Each process can trigger multiple responses and have differential impacts in time and space. In this sense, the concepts of balance used in the classic coastal sedimentary balance investigations are questioned.The study area does not have a protected area category, so its environmental assessment in this sense must consider dynamical processes.

Long-term shoreline evolution (Late-Holocene – 2018) of the Channel 15 coast (Samborombón bay, NE – Buenos Aires province, Argentina)

“…These islets may have acted as a barrier to wave action, contributing to the sedimentation processes between the islets and the coast, and marsh progradation in Sector 1 (Figure 4). Similar processes were registered in Punta Atalaya (D’Amico et al, 2019) and Isla Paulino (D’Amico, 2020), north to the study area.…”

“…Both sectors are located north and south of the northern tip of the bay, respectively (Figure 1). South of the bay, negative trends were detected in the Ajó river mouth between 1964 and 2017 (Bacino et al, 2020) and the estuarial sector of Punta Rasa between 1937 and 2018 (D’Amico et al, 2019) (Figure 1).…”

Floods of movement

“…Punta Indio and Atalaya are rural, livestock farming-oriented, areas located at the Southern part of the La Plata Estuary. Households face natural hazard risks from flooding and sea-level rise as well as salinization and coastal erosion (Cellone et al, 2016(Cellone et al, , 2018D'Amico et al, 2019).…”