Potencial de utilização do sensoriamento remoto para monitoramento da água do resevatório Passo Real

Abstract

The built of reservoirs provides progress by the exploitation and multiple use of water resources, but it also brings changes and impacts in the quality of water. One of the main interests in the use of products of remote sensing in water environments is to verify the spatial and temporal variation of water composition, enabling the investigation on the origin and displacement of specific substances in suspension or substances dissolved in water. In this context, the general objective of this thesis consists of verifying the potential use of remote sensing for monitoring water in Passo Real reservoir. In order to achieve this, three specific objectives were stipulated; 1) To characterize and verify the relation among physical limnologic, chemical and biological variables of Passo Real reservoir; 2) To analyze the influence of the constituents optically active in the spectral response of water in the reservoir and to verify the potential use in the techniques of first derivative and continuum removal for the extraction of information in spectrum of reflectance and identification of wavelength with the finest correlation with limnologic variables; and 3) To evaluate the potential use of images LISS-III/Resourcesat-1 in the estimate of constituents optically active in the water of Passo Real. The variables of water color, transparency, temperature, turbidity and dissolved oxygen were obtained in field and the total of suspended solids, dissolved solids, Hidrogenionic potential, electrical conductivity and chlorophyll-a were determined in laboratory after collection of samples in field. In fieldwork, the measures of water reflectance factor were collected between wavelengths of 400 and 900nm as use of spectroradiometer. The images of satellite used for the analysis of water reflectance were produced by the satellite resourcesat-1, Sensor LISS-III. The spatialisation of the limnologic data obtained in situ was performed by interpolation and the spatializations of estimated data by satellite were obtained by slicing the image generated in the insertion of equations obtained in the models. The strong correlation between data of total of solids in suspension with the turbidity and transparency of water increases the importance of analysis integrated in the variables optical of water environment. From the analysis of the reflectance spectra, it was possible to infer the performance of the components optically active in the spectral characteristics of water. The use of techniques for interpretation of spectrum was important to the extraction of information and analysis of data. Each technique highlighted well the given spectral characteristics. From the set of available data, it was possible to produce models capable of estimating the total of suspended solids, the turbidity and the transparency of water with only one spectral band, band 3, from the sensor LISS-III/Resourcesat-1. By the application of the technique spectral band reason, it was possible to generate a model for the estimate of concentration of chlorophyll-a.