Elaboração e avaliação de uma ferramenta computacional para delimitação automática e caracterização morfométrica de bacias hidrográficas a partir de um MDE

Abstract

The watershed can be understood as an integrated system among all its constituent elements, soil, water, vegetation and fauna, where every natural or anthropic disturbance causes reactions in the natural dynamics of the basin, forcing it to adapt to this new environment. Anthropic actions are related to socio -economic activities, that in the face of inadequate environmental planning and management, dissociate from environmental aspects getting to conflict with the ecosystem's capacity to support. Facing this panorama, several countries have sought to rebalance the integrated dynamics of watersheds, incorporating principles and norms for the management and planning the effects deriving of the unbalance of the system. The project and planning of hydric resources need information that allows the evaluation of the hydrological behavior of the basin. For this, it is necessary to quantify all the morphometric characteristics of the basins, because, when establishing relationships and comparisons among such characteristics and the known hydrological data, one can indirectly determine the hydrological values in places where data are missing. Commonly, to initiate a hydrological or environment al analysis, preliminarily the delimitation of the watershed is proceeded, which until recently it softwares and the digital representation of relief from remote sense techniques, it became possible to automate this task. From this, it sought with this work to elaborate a computational tool, using R computational language, for the delimitation and morphometric characterization of watershads from global Digital Elevation Models (DEM), in automatic way, that permits provide quickly the morphometric parameters, offering to the user also to conclude by the model that best suit it need. The objective of this study is to evaluate the elaborated tool with a study of comparative in four river sub - basins in the state of Tocantins, with different relief characteristics, presentingan alternative for hydrological validation of digital elevation models from the SIGEF (Portuguese abreviation of System of Land Management) altimetric data. With the case study, it was concluded that the proposed tool works satisfactorily for what is propcompared with the r.basin.py program from the Grass GIS software, the tool presented similar results in relation to the values of most of the morphometric parameters; however, a lower drainage network detail, associated with differences in the spurious data filling algorithm, though, this problem can be circumvented by adjusting the initial threshold values configurations.