Mapeamento Plani-Altimétrico da microrregião do Salgado paraense a partir de procedimentos fotogramétricos

Abstract

The Coastal Microregion of Salgado Pará is characterized by a low topographic gradient controlled by paleopavements (stone layers) and lateritic crusts, having its model developed in Cenozoic units (Pirabas and Barreiras Formations) and Quaternary (Post-Barriers and recent sediments). From a geographic and geomorphological point of view, this area is subdivided into two geosystems: in resistasia of regressive character, with geomorphogenesis associated with anthropic activities of continental domain; and, marginal-mosaic with resistasia and biostasis responsible for the morpho-environmental susceptibility of the coastal domain. The photogrammetric and morphotopographic mapping of the Coastal Microregion of Salgado Paraense allowed the elaboration of eleven topographic maps (systematic and non-systematic) suitable for morpho-environmental studies. An integrated photogrammetric system of a 1st order analog stereo-returner (universal type) - Topocart-D/Zeiss and Orthophot-E/Zeiss differential optical transformer was used to make the maps, aided by other cartographic systems such as interpretoskop-C/Zeiss, aerosktchmaster /Zeiss and ST-4/Wild stereomicrometer. The modeling of the data arranged in four levels of stereotopographic density, showed the photogrammetric capacity of Topocart-D, and the mapping alternatives for the Coastal Microregion of Salgado Paraense. a predominantly transgressive system with localized regressive pulses. These processes are also indicated by the morphodynamic changes of the geofacies, whose morphotopographic correlations allowed the compartmentalization of the Coastal Microregion of Salgado Paraense in the NE, SW and E topographic domains, which encompass the morphological domains of esplanade, coastal plain and estuarine plain. The fluvial-coastal systems of Japerica-Primavera-Quatipuru, Pirabas-Inajá, Arapepó-Urindeua and Maracanã-Caripi characterize the NE, SW and E domains. dissected developed in lateritic crusts, in which concave amphitheaters of springs (catchment basins) and erosive levels are inserted; the coastal plain, which corresponds to the coastal portions directly influenced by the ocean, is characterized by beaches, active and inactive cliffs, active and degraded mangroves, platforms of laterite blocks and mobile and degraded dune cords; and, the estuarine plain is formed by estuaries filled with mud and sand banks, generally degraded dunes, active and inactive cliffs, elliptical to elongated hills, trapezoidal “strained”, saline wetlands with a lot of organic matter, pre-salt, peripheral igapós and penelagos in the form of double-bottomed saucers. In the SW topographic domain: the esplanade shows a flat-shaped relief with a table top and erosive levels, controlled by paleopavements, the relief also being characterized by valleys in the “◡” shape and springs of the dale and thalweg types; the coastal plain exhibits narrow oceanic beaches with curved ends (spits), inter-dune fields, active and inactive cliffs, leterite block platforms, abrasion platforms and oceanic mangroves; and, the estuarine plain encompasses unfilled estuaries and partially filled estuaries. Topographic domain E, encompasses only the esplanade (also controlled by paleopavements) and estuarine plain compartments, and belongs to an independent morphotopographic system, featuring a single interfluvial corridor. The esplanade shows normal short and convex slopes, inserted in multidirectional drainage patterns; and, the estuarine plain is bordered by active and inactive large cliffs. This estuarine plain has numerous underwater and subaerial indents formed by blocks of laterite and kilometric lateral mangroves penetrating into transverse valleys in the E-W direction.