Monitoramento e avaliação de processos erosivos marginais em reservatórios de usinas hidrelétricas por meio de varredura a laser
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Data
2016-02-26
Autores
Moraes, Marcus Vinícius Antunes de [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
As erosões marginais são causadas por uma série de fatores que impactam ou atenuam o processo, tais como o tipo de erosão, a constituição do solo, ventos, regime hidrológico, presença e tipo de vegetação, entre outros. Os processos de erosão marginal ocorrem às margens de corpos d’água e demandam estudos específicos para seu entendimento e possível mitigação. Os escâneres LASER (Light Amplification by Stimulated Emission of Radiation) móveis são indicados para o levantamento de dados para séries temporais, principalmente em áreas com alterações pequenas ao longo do tempo, em virtude de sua elevada resolução espacial e acurácia. Sistemas de escaneamento LASER dotados de posicionamento GNSS/RTK (Global Navigation Satellite System/Real Time Kinematic) têm a vantagem de demandar menos etapas de pós-processamento, uma vez que os resultados imediatos do levantamento são as nuvens de pontos prontas para edição, e com precisão compatível à do RTK. Neste trabalho apresenta-se uma proposta metodológica para a execução dos levantamentos com uso de sistema LASER móvel embarcado, pós-processamento dos dados, geração de produtos e análise dos resultados para fins de monitoramento de processos de erosão marginal. Experimentos para caracterização da acurácia dos levantamentos realizados com uso do escâner móvel MDL Dynascan M150 mostraram que a acurácia média dos levantamentos varia de 5 a 15 cm, conforme a distância da base RTK à área de levantamento. Ainda são apresentados resultados obtidos em um estudo de caso, que demonstram a eficiência da metodologia proposta.
River bank erosions are caused by a set of factors that affect or attenuate the process, such as type of erosion, constitution of the soil, and environmental factors such as wind, water regime, presence and type of vegetation, among others. Bank erosion processes occur on the banks of water bodies and require specific studies for their understanding and possible mitigation. Mobile LASER (Light Amplification by Stimulated Emission of Radiation) scanner systems are suitable to survey data to compose temporal series, mainly in areas with small changes over time, due to their high spatial resolution and accuracy. Laser scanning systems equipped with GNSS/RTK (Global Navigation Satellite System/Real Time Kinematic) positioning have advantage because demand less post-processing steps, since the immediate results of survey are point clouds ready for editing, and their accuracy is compatible with RTK accuracy. This work presents a methodology carrying out Mobile LASER surveys, post-processing data, product generation and analysis of results for monitoring purposes of river bank erosion processes. Experiments to characterize the accuracy of surveys conducted with the use of mobile laser scanner MDL DynaScan M150, show that mean accuracy of surveys vary from 5 to 15 cm according to the distance of RTK basis to survey area. Besides, are presented results of a case study that demonstrate the efficiency of the proposed methodology.
River bank erosions are caused by a set of factors that affect or attenuate the process, such as type of erosion, constitution of the soil, and environmental factors such as wind, water regime, presence and type of vegetation, among others. Bank erosion processes occur on the banks of water bodies and require specific studies for their understanding and possible mitigation. Mobile LASER (Light Amplification by Stimulated Emission of Radiation) scanner systems are suitable to survey data to compose temporal series, mainly in areas with small changes over time, due to their high spatial resolution and accuracy. Laser scanning systems equipped with GNSS/RTK (Global Navigation Satellite System/Real Time Kinematic) positioning have advantage because demand less post-processing steps, since the immediate results of survey are point clouds ready for editing, and their accuracy is compatible with RTK accuracy. This work presents a methodology carrying out Mobile LASER surveys, post-processing data, product generation and analysis of results for monitoring purposes of river bank erosion processes. Experiments to characterize the accuracy of surveys conducted with the use of mobile laser scanner MDL DynaScan M150, show that mean accuracy of surveys vary from 5 to 15 cm according to the distance of RTK basis to survey area. Besides, are presented results of a case study that demonstrate the efficiency of the proposed methodology.
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Palavras-chave
Monitoramento, Erosões Marginais, Escâner LASER