Navegando por Assunto "Erosion"
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Item Acesso aberto (Open Access) Análise integrada da paisagem e processos de erosão costeira na ilha de Atalaia, Salinópolis, Pará(Universidade Federal do Pará, 2024-03-27) SOUZA, Ewerton Müller da Silva; ANDRADE, Milena Marília Nogueira de; http://lattes.cnpq.br/1930321094483005; https://orcid.org/0000-0001-5799-7321The study aims to analyze the landscape and erosion susceptibility processes on Atalaia Island, Salinópolis, Pará, as a basis for coastal management policies. The objective unfolds in examining the coastline position between 2002 and 2022, identifying coastal dynamics through geoindicators, analyzing landscape units, and the degree of susceptibility to erosion on the island. To achieve the objectives, the study area was divided into three sectors: Espadarte, Atalaia, and Sofia. The materials and methods used include satellite images for a twenty-year multi-temporal analysis, with polygon change analysis techniques, areal and linear rates. For this assessment of coastal changes, the Digital Shoreline Analysis System (DSAS) plugin was used in the Geographic Information System environment of ArcMap 10.5. The use of geoindicators was granted through field sheets with the identification of natural or anthropogenic elements that pointed to the movement of the coastline. For the landscape analysis, the theoretical basis of landscape geoecology and the use of geoprocessing to generate a map of landscape units were used. The study revealed areas of high susceptibility with 47,798m², mainly in sector A, in this sector, geoindicators such as the front strip of vegetation modified by erosion (44) and the presence of retaining walls and other constructions in contact with the beach arch or on the surface of estirance (64) stand out. The areas of moderate susceptibility were present, prominently in Sector B, with an area of 66,950m², in this sector, the geoindicators of water/sewage piping or energy poles, located on the beach arch in a situation of destruction by physical agents (54) and the presence of retaining walls and other constructions in contact with the beach arch or on the surface of estirance (62) stand out. The areas of low susceptibility to erosion were present, most evidently, in Sector C, with an area of 341,274.1m², in this sector, the geoindicator related to the width of the post-beach/sandy berm surface (70) stands out. The results of the landscape analysis allowed the understanding of the structure and functioning of the fluvio-marine plain, urban areas, open areas, moving dunes, and beach and post-beach. The investigation offers a dynamic perspective on the erosion processes of Atalaia Island from the employed methodology, thereby, the results indicate the need for more effective coastal management strategies, underlining the importance of an integrated approach that considers both physical and socioeconomic aspects to mitigate adverse impacts on local communities and the ecosystem.Item Acesso aberto (Open Access) Modelagem numérica-experimental da produção de sedimentos de pequenas bacias hidrográficas da Amazônia(Universidade Federal do Pará, 2021-04-22) BARBOSA, Ana Júlia Soares da Silva; BLANCO, Claudio José Cavalcante; http://lattes.cnpq.br/8319326553139808; https://orcid.org/0000-0001-8022-2647Erosion is a process of direct impact in urban and rural environments. The understanding of this process requires the use of models and techniques of geoprocessing and field, for approximate estimation of the realized one, since it is a phenomenon with many variables to be taken into account. For the present study, two models were used to generate data in a small Amazon basin. The USLE (universal soil loss equation) and also the modified MUSLE version. For both models, the common factors (K, LS, C and P) were determined. For USLE, the calibration occurred for rain erosivity, which is the differential factor of this model. After USLE application with calibrated R factor, the model was applied to the study area with an average soil loss of 1.99 ton. ha-1.year-1, for a period of 21 years. For MUSLE, the differential variables are the hydrological variables (Q and qp) were determined by analyzing the hydrographs observed with the aid of a digital filter. Two methods of calibration and validation have been done for MUSLE. Method 1 calibrated the factors ɑ and b, with sediment production data measured from 62 flood events from 2012 to 2014. The values found for factors ɑ and b were equal to 19.90 and 0.60, respectively. MUSLE was validated with sediment production data measured from 62 flood events in the years 2014 and 2015. The validated MUSLE equation represented in a satisfactory way, in more than 70%, the data of soil loss observed in the hydrographic basin of the Igarapé da Prata. Method 2 calibrated only the value of a, using the solid discharge curve with potential regression for the years 2012 and 2013, which showed R² of 0.70 and 0.68, respectively. The value of ɑ obtained was 17.25, and was applied to MUSLE, keeping the value of b at 0.56, the original value of the model. The validation for the latter method proved to be adequate, with an R² of 0.69. These results validate the empirical models for the region with experimental activities, which corroborates for the production of sediment information in the Amazon region, as a way of maturing and the search for new research, for the understanding of the impacts arising from the transport of soil between areas and in the water environment.