El Islote El Palmar, resultado de una evolución a largo plazo de la distribución del drenaje entre los Ríos Daule y Babahoyo en la Cuenca del Guayas

Abstract

Se analizó la forma de la red de drenaje de la parte sur de la Cuenca del Guayas, desde Quevedo al norte hasta la confluencia de los ríos Daule y Babahoyo al sur. La idea de que la distribución del drenaje en la Cuenca del Guayas es variable y puede tener un efecto sobre la repartición de los caudales respectivos de los ríos Daule y Babahoyo, es basada en dos elementos, uno geológico y el otro histórico.

We analyses the morphology and sedimentation of the El Palmar Islet considering the drainage network of the southern part of the Guayas Basin, upstream of the confluence of the Daule and Babahoyo Rivers. The southern part of the Guayas Basin is characterized by the occurrence of numerous abandoned river segments, suggesting a great instability of the drainage network. The drainage divide between the Daule and Babahoyo Rivers is not clearly defined. In the area of Vinces the drainage is deviated to the east along light structural elevations formed by a fault or fault associated flexures that bend the surface of the basin. Based on abandoned fluvial morphology along the small Sabanilla River (conNected to the Daule River, as well as others in the central part of the Guayas Basin) we suggest that the Vinces River was previously a tributary of the Daule River. The general tendency of the evolution of the drainage is an eastward migration, removing tributaries of the Daule River to redirect them toward the Babahoyo River. The El Palmar Islet appeared initially as a longitudinal bar, but the recent evolution is that of a tidal flat sedimentation. The morphology of the islet on the side of the Babahoyo River suggests that the drainage of the Daule River is contained by the higher discharge of the Babahoyo River. This evolution is consistent with the distribution of the drainage of the two rivers observed at the scale of the upper Holocene. Our analysis suggests that the long term evolution of the El Palmar Islet has recent short term parameters such as the Daule-Peripa dam. This long term evolution suggests that the presence of the islet is probably well established, even if short term variation can result in a temporary decrease of the sedimentation.