Sedimentological and Stratigraphic Analysis of the Bunche River Estuary, Esmeraldas Province – Ecuador

Abstract

In the present study, a sedimentological and stratigraphic analysis was conducted on sediments collected in the Estuary of the Bunche River to understand the predominant sediment transport and deposition processes. Understanding sediment transport dynamics in this environment will provide foundational information for coastal planning, water quality management, biodiversity conservation, climate change adaptation, among other important aspects. The study was conducted on sediments collected from three cores, each with a maximum length of 60 cm, acquired from the coastal zone, the internal estuarine channel, and an internal bar within the estuary. Granulometric, textural, compositional, and statistical analyses were performed. Based on the analyses conducted, it was determined that the sediments in the estuary range from very fine to fine sand and do not exhibit significant compositional variations among the sub-environments. Specifically, sediments in the coastal zone are predominantly well-sorted, with mostly positive skewness values and a very leptokurtic nature, suggesting a high-energy transport and deposition environment. Sediments collected in the internal channel and the estuarine bar are primarily characterized by highly positive skewness values, being moderately sorted and mostly platykurtic in nature. This is interpreted as an environment of relatively lower energy deposition compared to the coastal zone, resulting in the accumulation of finer sediments. Both graded suspension and uniform suspension are the primary factors for transport within shallow turbulent waters. In the coastal zone, this is associated with the constant action of waves and littoral currents, while in the internal estuarine zone, fluvial and tidal currents have a greater impact.