Geomorphology and Evolution of El Chisguete Estuary, Baja California Sur, Mexico.

Abstract

El Chisguete Estuary forms part of the Santo Domingo – Magdalena – Almejas lagoon complex. It is one of the state's lagoon ecosystems with the greatest biodiversity, fishing, and ecotourism attractions. This justifies the analysis of its geomorphology and evolution, employing geomorphologic and morphodynamics methodologies. The estuary corresponds to a lagoon and stands out among other marginal water bodies by its developing two barriers. Terrigenous deposits constitute its geomorphology in the alluvial plain, while deposits towards its coastal margin are marine and wind-originated. This forms marshes, mangrove swamps, dunes, barriers, and beaches, which become neighboring ecosystems. In general, the estuary is shallow, with a mean one-meter depth. Moreover, tide currents and local wave action condition its hydrodynamics. The morphological processes of the east (E) and west (W) barriers for the analyzed period (1973 – 2022) show an evolutionary rate (∆S / ∆T) of 0.027 Km2 and 0.0034 Km2, respectively. Therefore, it maintains a good preservation state, where its changes are presented as a remodeling of natural origin. This makes it possible to use the evolutionary state of the barriers as an environmental geo-indicator.