ABSTRACT
In this study, multisensor remote sensing datasets were used to characterize the land use and land covers (LULC) flooded by Hurricane Willa which made landfall on October 24, 2018. The landscape characterization was done using an unsupervised K-means algorithm of a cloud-free Sentinel-2 MultiSpectral Instrument (MSI) image, acquired during the dry season before Hurricane Willa. A flood map was derived using the histogram thresholding technique over a Synthetic Aperture Radar (SAR) Sentinel-1 C-band and combined with a flood map derived from a Sentinel-2 MSI image. Both, the Sentinel-1 and Sentinel-2 images were obtained after Willa landfall. While the LULC map reached an accuracy of 92%, validated using data collected during field surveys, the flood map achieved 90% overall accuracy, validated using locations extracted from social network data, that were manually georeferenced. The agriculture class was the dominant land use (about 2,624 km2), followed by deciduous forest (1,591 km2) and sub-perennial forest (1,317 km2). About 1,608 km2 represents the permanent wetlands (mangrove, salt marsh, lagoon and estuaries, and littoral classes), but only 489 km2 of this area belongs to aquatic surfaces (lagoons and estuaries). The flooded area was 1,225 km2, with the agricultural class as the most impacted (735 km2). Our analysis detected the saltmarsh class occupied 541 km2in the LULC map, and around 328 km2 were flooded during Hurricane Willa. Since the water flow receded relatively quickly, obtaining representative imagery to assess the flood event was a challenge. Still, the high overall accuracies obtained in this study allow us to assume that the outputs are reliable and can be used in the implementation of effective strategies for the protection, restoration, and management of wetlands. In addition, they will improve the capacity of local governments and residents of Marismas Nacionales to make informed decisions for the protection of vulnerable areas to the different threats derived from climate change.
Subject(s)
Cyclonic Storms , Floods , Remote Sensing Technology , Floods/statistics & numerical data , Remote Sensing Technology/instrumentation , Remote Sensing Technology/methods , Environmental Monitoring/methods , Humans , AlgorithmsABSTRACT
The growth study in width of Chasmagnathus granulatus Dana, 1851 was based on biometric data of 1,940 specimens colleted at Lagoa do Peixe, state of Rio Grande do Sul, Brazil. The samplings were realized from July/1994 to June/1995. For each captured specimens the sex and width of cephalothorax were recorded. The von Bertalanffy's model was utilized for the growth description. The growth curves in width (mm), for data obtained through the modal progression, are described by the equations: Lt= 44,69 [1- e -0.0066(t+20,45)] and Lt= 37,63 [1- e -0.0072(t+21,92)], resulting in a maximum estimated age of 2 years for males and females.
O estudo do crescimento em largura da carapaça de Chasmagnathus granulatus Dana, 1851 foi baseado em dados de 1940 exemplares coletados na Lagoa do Peixe, Estado do Rio Grande do Sul, Brasil. As coletas foram realizadas de julho/1994 a junho/1995. Os caranguejos foram coletados manualmente nas margens da lagoa e em laboratório foram separados por sexo e a largura da carapaça mensurada. O modelo de von Bertalanffy foi utilizado para a descrição do crescimento. As curvas de crescimento em largura (mm), para dados obtidos através da progressão modal, são descritas pelas equações: Lt= 44,69 [1- e -0.0066(t+20,45)] e Lt= 37,63 [1- e -0.0072(t+21,92)], resultando em idades máximas estimadas de 2 anos para ambos os sexos.
ABSTRACT
The growth study in width of Chasmagnathus granulatus Dana, 1851 was based on biometric data of 1,940 specimens colleted at Lagoa do Peixe, state of Rio Grande do Sul, Brazil. The samplings were realized from July/1994 to June/1995. For each captured specimens the sex and width of cephalothorax were recorded. The von Bertalanffy's model was utilized for the growth description. The growth curves in width (mm), for data obtained through the modal progression, are described by the equations: Lt= 44,69 [1- e -0.0066(t+20,45)] and Lt= 37,63 [1- e -0.0072(t+21,92)], resulting in a maximum estimated age of 2 years for males and females.
O estudo do crescimento em largura da carapaça de Chasmagnathus granulatus Dana, 1851 foi baseado em dados de 1940 exemplares coletados na Lagoa do Peixe, Estado do Rio Grande do Sul, Brasil. As coletas foram realizadas de julho/1994 a junho/1995. Os caranguejos foram coletados manualmente nas margens da lagoa e em laboratório foram separados por sexo e a largura da carapaça mensurada. O modelo de von Bertalanffy foi utilizado para a descrição do crescimento. As curvas de crescimento em largura (mm), para dados obtidos através da progressão modal, são descritas pelas equações: Lt= 44,69 [1- e -0.0066(t+20,45)] e Lt= 37,63 [1- e -0.0072(t+21,92)], resultando em idades máximas estimadas de 2 anos para ambos os sexos.