Ângela Maria Klein Hentz

Environmental fragility of Iguaçu river watershed, Paraná, Brazil

The aim of this study was to analyze the environmental fragility of Iguacu River watershed, Parana. Regarding fragility potential, most watersheds fell under...

Comparing the Performance of Ground Filtering Algorithms for Terrain Modeling in a Forest Environment Using Airborne LiDAR Data

The aim of this study was to evaluate the performance of four ground filtering algorithms to generate digital terrain models (DTMs) from airborne light detection and ranging (LiDAR) data. The study area is a forest environment located in Washington state, USA with distinct classes of land use and land cover (e.g., shrubland, grassland, bare soil, and three forest types according to tree density and silvicultural interventions: closed-canopy forest, intermediate-canopy forest, and open-canopy forest). The following four ground filtering algorithms were assessed: Weighted Linear Least Squares (WLS), Multi-scale Curvature Classification (MCC), Progressive Morphological Filter (PMF), and Progressive Triangulated Irregular Network (PTIN). The four algorithms performed well across the land cover, with the PMF yielding the least number of points classified as ground. Statistical differences between the pairs of DTMs were small, except for the PMF due to the highest errors. Because the forestry sector requires constant updating of topographical maps, open-source ground filtering algorithms, such as WLS and MCC, performed very well on planted forest environments. However, the performance of such filters should also be evaluated over complex native forest environments.

CARACTERIZAÇÃO DA FRAGILIDADE AMBIENTAL DE UMA BACIA HIDROGRÁFICA URBANA NO MUNICÍPIO DE SANTA MARIA - RS

O Geoprocessamento tem sido considerado instrumento fundamental na definicao de politicas de intervencao e gestao ambiental. O presente trabalho objetiva caracterizar a fragilidade ambiental da sub-bacia hidrografica do arroio Cadena, inserida no municipio de Santa Maria, regiao central do estado do Rio Grande do Sul, com o uso de geotecnologias. Utilizou-se o metodo adaptado proposto por Ross em (1994), que e baseado na compreensao das caracteristicas e da dinâmica do ambiente natural. Para avaliar a fragilidade foram estabelecidos pesos ou notas a cada situacao que as variaveis do processo apresentaram, processadas em ambiente SIG a partir da ferramenta algebra de mapas. A bacia hidrografica possui uma fragilidade potencial fraca, com 52,9 % em relacao a area total, consequencia da declividade plana agregada ao tipo de solo. Apresenta uma fragilidade emergente forte, com 37,7% da area total, devido ao processo de urbanizacao associado a ocupacoes irregulares e uso inadequado dos recursos naturais. A metodologia apresentada foi considerada satisfatoria, pois, foi possivel analisar a fragilidade ambiental da area de estudo, e ainda, os resultados obtidos indicam a importância de se implantar um plano de gerenciamento urbano e ambiental no municipio de Santa Maria.