A dinâmica hidrográfica na região sul do estado de Goiás
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2020-10-23
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Universidade Federal de Goiás
Resumo
Brazil is a world leader concerning water resources, and for its intense agricultural production.
In the state of Goiás alone, more than 26 million hectares of land is earmarked for agricultural
activities, and water availability is essential for the sustainability of these activities. Because of
this, physical changes in hydrography may occur as a result of the increase in agricultural
production, since the implementation and maintenance of these activities require interventions
such as dams, water abstraction, irrigation, and deforestation. The objective of the research is
to map the changes in hydrography in the Water Resources Management Planning Units
(UPGRHs) of the affluent Goianos of Baixo Paranaíba and Rio dos Bois in the last three decades
and to verify if they are associated with changes in use and coverage from the soil. To identify
and map this water dynamics, a computational code was developed in the Java programming
language and executed within the Google Earth Engine (GEE) platform, where the
classification of the presence of water was carried out using the Landsat satellite images in the
years 1987, 2007 and 2017. After mapping the hydrography for the aforementioned years, the
data in the form of images were exported to a Geographic Information System (GIS) computer
program, for area calculations and comparison of changes about hydrography. It was found that
between 1987 and 2007 there were few changes in hydrography, already in 2017, it is possible
to notice significant changes mainly to the emergence of large reservoirs. As a basis for
calculating the hydrographic areas in this 30-year interval in the UPGRHs in the study area, a
significant increase was observed from 505.16km² to 630.46km², in water depth, corresponding
to an increase of 24.80%. Likewise, changes in land use and coverage were observed. The
quality of the hydrography mapping elaborated in this research was evaluated in comparison
with the mapping carried out for the same years by the MapBiomas project. By comparing the
areas found by the two mappings, hydrographic omissions were identified in the MapBiomas
data, ranging from 41% to 63%. This discrepancy does not invalidate the data provided by
MapBiomas, since the classification methodology and area of coverage of the mapping is for
the entire Brazilian territory, however, this comparison found the good quality of the mappings
carried out within the scope of the research. Thus, the results obtained demonstrate that there is
a relationship between changes in land use and hydrography and that these changes can be
identified from images with a special resolution of tens of meters.
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CASTILHO, M. P. S. F. A dinâmica hidrográfica na região sul do estado de Goiás. 2020. 56 f. Dissertação (Mestrado em Engenharia Ambiental e Sanitária) - Universidade Federal de Goiás, Goiânia, 2020.