Caracterização limnológica e espectral de dois compartimentos aquáticos do reservatório Itaipu

Abstract

Inspired by the knowledge that limnological variables in damned bodies of water are a reflection of physical characteristics and from usage and occupation of the land surrounding the water system, and so establishing on the spectral response of the water typical features of optically active components. This study has as a goal to comprehend the behavior from limnological variables making use of remote sensing in the aquatic compartments at Passo Cuê and São Francisco Verdadeiro, located both in the Itaipu reservoir. And as specific goals (i) to comparatively analyze the chlorophyll a spatial limnological distribution, electrical conductivity, dissolved oxygen, hydrogenionic potential (pH), suspended solids and water transparency in the observed aquatic compartments; (ii) to verify the influence of optically active components in the spectral response of the water in both aquatic compartments; (iii) to examine whether the spectral response of the bands 3 and 4 of the Operational Land Imager (OLI) sensor from the Landsat 8 satellite and the ratio of bands have 3/4 asustains any relation to the optically active components of the aquatic compartment at Passo Cuê. The limnological variables are spatialized use of the weighted average interpolation, and afterwards categories are sliced, in thematic format. The analysis of the behavior of the limnological variables on the main channel was done through the identification and measurement of the distance between sample points placed at the area of the main channel in the two aquatic compartments. In order to study the spectral data, collected in situ, the techniques of analysis of spectral reflectance, smoothing of the spectral and derived curve were used. The image from the Landsat 8 satellite, dated to August 22nd, 2014, which covers Passo Cuê aquatic compartment is obtained as requested on the USGS site in reflectance with geometric and atmospheric accuracy. The limnological variables present a uniform behavior at Passo Cuê aquatic compartment, fact that does not occur at São Francisco Verdadeiro aquatic compartment. In addition to that, the behavior of limnological variables allows the characterization of aquatic compartment zones. The limnological variables with exception of the dissolved oxygen, have the tendency to present in the lake zone of the aquatic compartments quite similar concentration values, which shows the standardization of the water from the aquatic compartment to the rest of the reservoir. The usage of the derived technique highlights the presence of the chlorophyll pigment a in the fluvial zone of São Francisco Verdadeiro aquatic compartment. At Passo Cuê aquatic compartment, it was noticed, after using the images from Landsat 8 satellite that the uniform behavior and the low concentration of optically active components have a small influence on the spectral response of the water, fact that can be understood by the low values of associations obtained between the limnological and spectral variables gathered in situ in the aquatic compartment.