Influencia del area continental pampeana en la evolución morfologica del estuario de Bahia Blanca

the characteristics of the drainage basins are one of the most important factors defining the origin and evolution of estuaries. in the case of the bahía blanca estuary (fig. 1), the presence of morphologic units such as the colorado river and a series of depressions in the sw of la pampa province is connected to the genesis and evolution of the estuary since the pleistocene. the aim of the present article is to establish the possible paleomorphologic relationships between the estuary and the adjacent continental environment. bahía blanca estuary is the reception basin of a drainage basin located in the southwest of the buenos aires province, having a surface of the order of 3000 km2. the coast of the estuary can be divided in two sectors. to the north, it has a nw-se orientation, whereas, to the west, the coast trends approximately n-s. the former has over 110 km in length between salitral de la vidriera and baliza monte hermoso and the latter is located between the salitral and laberinto pt. with 130 km. to study the evolution of the area, visual analysis of satellite image charts from the igm (scales 1:100.000 and 1:250.000) were employed. once the morphologic unities were identified, they were digitized and assembled in a geographic information system (gis) supported on the landsat 7 satellite image etm path/row 227 - 087 provided by conae. all igm topographic charts of the area were also digitized and transferred to the gis. a total of 8 field surveys were made to define the geomorphologic and geologic conditions and topographic surveys of the valleys and depressions were also performed. furthermore, an aerial survey of the estuary and its surroundings were made. two units were defined as continental and transitional domains (fig. 1). in the former, the morphology is defined by the subaerial sedimentation processes associated to the presence and evolution of the hydrographic basin. the transitional domain includes the coastal and estuarine sectors. on the conti