Abstract In Brazil, landslides are frequent, causing deaths and property damage, and occur under the influence of natural and/or anthropic conditions. Rain acts as the main non-anthropic agent in triggering this phenomenon. Because of this, the prediction of landslides becomes an essential tool for managing high-risk areas. The Metropolitan Region of Recife (MRR) has a large history with numerous cases of mass movements over the years. Currently, research points out improvements in the quality of forecasts by including hydrological information, such as soil moisture, in warning systems. Given the importance of measuring soil moisture in situ, a network of equipment consisting of rain gauges and capacitive moisture sensors was installed in the MRR, to monitor rainfall and soil moisture in an integrated manner. The objective of this article is to understand the hydrological conditions of the soil in two high-risk areas of the MRR, built over the Barreiras Formation to set the foundations for the development of a Landslide Early Warning System (LEWS) that integrates rain and humidity. The data showed that the variation in soil moisture is very dependent on rainfall and presents sudden variations in moisture with increasing hourly rainfall. The data also revealed that the monitored soils remained wet for approximately six months in the year 2022, highlighting the potential for moderate rainfall during this period to trigger landslides.

Abstract Interferometry is a technique that can be applied to SAR (Synthetic Aperture Radar) images that allow obtaining Digital Elevation Models, displacement measurements and assistance for monitoring large areas and/or engineering constructions. The objective of this paper is to present aspects related to the technique of Interferometry SAR (InSAR) applied to the monitoring of slopes. To do so, a systematic bibliographical review was used, through research platforms in scientific collections, in order to highlight the functioning and method of operation of InSAR. Besides that, the practical experience of the authors contributed to a critical analysis of the remote sensing technique addressed. The results show theoretical aspects related to the operation of SARs on board satellites, highlighting their characteristics, orbital systems, types of imaging geometry, as well as the principles of interferometric processing of SAR images. Practical applications demonstrate the potential of InSAR with an emphasis on slope monitoring, highlighting its ability to acquire topographic information on a millimeter scale, monitoring the long-term temporal evolution of displacements, the possibility of composing a monitoring system allowing directing the implementation of other instruments for evaluating the in situ conditions and some limitations regarding the time interval (satellite revisit time) for the acquisition of the displacement data. Synthetic Radar Models andor or constructions (InSAR slopes so used collections addressed satellites characteristics systems geometry scale longterm long term displacements satellite data

Abstract In the design of piles partially embedded in rock, the main factors that influence the strength and deformability of the rock and the transmission of loads from pile to rock are of utmost relevance to pile behavior. Most empirical methods were developed based on data from specific regions. Differences in geological conditions, drilling methods and other features are not considered in most procedures. The article deals with a case of piles partially embedded in rock located in the town of São Lourenço da Mata, Pernambuco, Brazil. The rock mass consists of ancient deposits, formed mainly by granites of different compositions, gneiss and schists. The deposits have been deformed by several tectonic processes. Results from 99 dynamic loading tests enabled comparison between the mobilized lateral and pile toe resistance, with the estimated capacity obtained from the design methods known in the literature. In the prediction, the lateral shear resistance due to pile penetration in residual soil was also considered. Because failure was not reached in the dynamic tests, the estimated capacity was higher than the mobilized resistance.The resistances mobilized by the pile shaft friction in soil, by the pile shaft friction in rock and by the mobilized toe resistance in rock in the dynamic loading tests are compared to design methods known in the literature. Five static loading tests indicated failure loads greater than the mobilized resistance in the dynamic methods. The comparisons allow recommendations of the most consistent design methods to use in similar cases in practice.

Abstract This work had as objective to carry out the construction of typical soil profiles of the main existing deposits in the city of Maceio from a database of SPT boreholes, built in GIS environment. In total, 1,686 records of drilling were specialized in sediments of the Barreiras Formation, Coastal Deposits, and lagoons-river, presenting the most frequent characteristics, exemplified through representative profiles. The Barreiras Formation, which covers about 75% of the urban area of the city, presented profiles with a predominance of clayey, without water level records. The deposits lagoons-river, located in the vicinity of Mundaú lagoon, were characterized by the significant presence of soft and organic clays, sometimes peat, it can reach large thicknesses and with the water table rising in certain regions. In the coastal plain, where the highest vertical construction indices in the city are concentrated, it presented an area with a predominance of fine to medium sand, with or without silt, and a water table varying between 1,00 m and 5,00 m. The analysis also allowed for the identification and mapping of the occurrence of limestone rock, sandstone rock, soft and organic clay rocks in the coastal plain, presenting a typical profile of their occurrence, helping to understand the geotechnical behavior of these materials in the studied region.

Resumo: A validação posicional de conjuntos de dados é uma etapa importante para os estudos de Cartografia, pois permite conhecer sua precisão, além de indicar a qualidade do processamento dos dados. No entanto, em se tratando de dados de Radar de Abertura Sintética (SAR), essa validação apresenta alguns desafios adicionais quando comparada à de imagens ópticas, devido às distorções geométricas. Utilizou-se alvos existentes, como placas de trânsito e postes de luz presentes na cena e os identificando na imagem como pontos de controle. Realizou-se a validação das coordenadas geográficas utilizadas como pontos de controle posicional planialtimétrico, utilizando tanto a ortoimagem de retroespalhamento de amplitude quanto o Modelo Digital de Terreno (MDT) gerados a partir do sistema InSAR. Empregou-se os testes NMAS, ASPRS e NSSDA juntamente com informações das Normas Brasileiras. Os resultados dos testes para a escala 1:10.000 foram: o teste NMAS - classe “A” no PEC e no PEC-PCD; o teste ASPRS - RMSE x = 1,317m, RMSE y = 1,231m e RMSEz = 1,145m; e o teste NSSDA - RMSEr = 1,802m, Precision r = 3,118m e Precision z = 2,244m. Esses resultados comprovam que pode-se utilizar os alvos propostos como pontos de controle e que os conjuntos de dados InSAR utilizados atendem à qualidade esperada para a geração de produtos geotécnicos para a escala 1:10.000.

Abstract: The positional validation of datasets is an important step for cartography studies since it allows learning about its accuracy, and also indicates the data process quality. However, the positional validation of Synthetic Aperture Radar (SAR) datasets have some additional challenges when compared to optical images due to the geometric distortions. We employ existing targets such as traffic signs and lampposts in the scene and identify them on the image as control points. We performed the validation of the geographic coordinates used as planialtimetric positional control points, using both the amplitude backscattering orthoimage and the Digital Terrain Model (DTM) generated from the InSAR system. We employed the NMAS, ASPRS and NSSDA tests along with information by the Brazilian Standards. This validation showed these control points presented the following results for 1:10,000 scale: NMAS test - class “A” in PEC and PEC-PCD; ASPRS test - RMSE x = 1.317m, RMSE y = 1.231m and RMSE z = 1.145m; and NSSDA test - RMSE r = 1,802m, Precision r = 3.118m and Precision z = 2.244m. These results prove we can use the proposed targets as control points and the used InSAR datasets meet the expected quality for generation of geotechnic products for 1:10,000 scale.

Abstract Soil behavior is influenced by the void ratio and bonds between grains. The aim of this study was to describe the strength behavior of an aeolian sand from the dunes of Natal, Brazil, artificially cemented in unconfined compression tests. The influence of cement content and moisture on molding and the validity of using the void/cement factor in estimating unconfined compression strength (UCS) were assessed. Tests were conducted with samples using three molding moisture contents (6, 9 and 12%), four cement contents (2.5, 5.0, 7.5 and 10%) and a void ratio of 0.6 (Dr = 95%). The results showed that unconfined compression strength rises with increase in cement content and decreasing in molding moisture. The void/cement factor proved to be a reliable parameter in predicting the behavior of sand from Natal for the dosage of soil cement.

RESUMO Estudos envolvendo vulnerabilidade de cidades à inundações necessitam do mapeamento de perigo e das áreas com potencial para inundação. O objetivo do artigo é desenvolver metodologia para mapeamento de indicadores de perigo e áreas inundáveis na escala de município. A área de estudo é o município de Ipojuca no Estado de Pernambuco com área de 527,11 km2 e uma população de 80.637 habitantes. A primeira metodologia consiste na simulação hidrológica-hidráulica para o baixo curso do rio Ipojuca com uso dos modelos HEC-HMS e HEC-RAS. A vazão gerada no modelo hidrológico do tipo chuva-vazão é utilizada como entrada do modelo hidráulico que simula o perfil da linha d’água no rio para a região de interesse. Com o perfil da linha da água, pode-se determinar a profundidade e a velocidade da água, que são elementos chave para a definição de indicadores de perigo. Com os resultados do modelo hidráulico, geraram-se seis indicadores de perigo: profundidade da água, velocidade do fluxo, combinação profundidade e velocidade, carga de energia, força do escoamento e intensidade (velocidade x profundidade). A outra metodologia procura identificar as áreas inundáveis de todo o território do município. Para isso, faz-se uso do índice topográfico da região e de uma matriz de custo de distância (que utiliza declividade e hidrografia), todos calculados com o modelo digital do terreno. A análise de risco é essencial para o planejamento e intervenção em áreas sujeitas a inundações. Para se avaliar risco, é necessária a caracterização do perigo e da vulnerabilidade. Os resultados do estudo em Ipojuca podem ser utilizados para a caracterização do perigo principalmente.

ABSTRACT Studies focusing on urban vulnerabilities due to river floods need the construction of hazard maps and definition of potential flood areas. The objective of this article is to describe the development of a methodology for hazard mapping of river floods and to map areas susceptible to inundation on a municipal scale. The study area is the municipality of Ipojuca – Pernambuco State with area of 527.11 km2 and population of 80,637 inhabitants. The first methodology uses the hydrologic-hydraulic simulation for the lower course of the Ipojuca River using the HEC-HMS and HEC-RAS models. The streamflow calculated in the rainfall-runoff model is used as input for the hydraulic model, to simulate the water surface profile in the river. This makes it possible to calculate the water depth and flow velocity, the key elements for the definition of hazard indicators. The results of the hydraulic model were used to generate the hazard indicators: water depth, flow velocity, combination of depth and velocity, energy head, flow force and intensity (flow velocity x water depth). The other methodology seeks to identify areas with potential for inundation considering the entire territory of the municipality. Topographic index of the region and a distance cost matrix (which uses slope and drainage) are the auxiliary variables for determination of this map. Both variables use the digital terrain model. Analysis of risk is essential for planning and intervention in areas susceptible to inundation. Both characterizations of hazard and vulnerability are needed to evaluate risk. The results of the study in Ipojuca can be used for hazard characterization.

As ravinas consistem em uma das formas de erosão hídrica com escoamento superficial concentrado em encostas de áreas degradadas e, ainda, sem escoamentos de subsuperfície. Os objetivos deste trabalho foram estudar o comportamento hidráulico do escoamento superficial das ravinas e determinar a erodibilidade (Kr) e a tensão crítica de cisalhamento (τc) na superfície de ravinas e, também, a erodibilidade (Kr) ao longo do perfil de encostas degradadas do litoral do Estado de Pernambuco. O experimento foi realizado em 2005, em um Latossolo Amarelo de textura argilosa pertencente à Formação Barreiras no município do Cabo de Santo Agostinho, PE. As parcelas foram delimitadas por chapas metálicas cravadas no solo no sentido do declive (1,0 m de largura por 3,0 m de comprimento). Os testes consistiram na aplicação de quatro níveis de vazão, determinando-se o volume de descarga líquida e a massa de sedimentos desagregados. As taxas de desagregação de solo foram lineares em relação às tensões de cisalhamento. Na superfície das ravinas, a erodibilidade (Kr) foi de 0,0016 kg N-1 s-1 e a tensão crítica de cisalhamento, de τc = 4,37 Pa. O baixo valor de erodibilidade e o alto de tensão crítica de cisalhamento de τc obtidos na superfície das ravinas possivelmente decorreram da formação de uma crosta superficial originada por ciclos de umedecimento e secagem. A erodibilidade (Kr) em profundidade variou entre 0,012 e 0,070 kg N-1 s-1, em função do teor de argila. O regime do escoamento superficial nas ravinas foi turbulento supercrítico e, portanto, semelhante ao do escoamento superficial nos sulcos de erosão, como descrito na literatura.

Ravines represent one of the formations resulting from water erosion, with concentrated surface water flow down hillsides of degraded areas, yet without subsurface water flow. The objective of this study was to evaluate hydraulic flow conditions in ravines as well as to determine soil erosion resistance parameters: soil erodibility (Kr) and critical shear stress (τc) on the ravine surfaces, as well as to determine soil erodibility at several depths of degraded hillsides along the coastline of the state of Pernambuco. The experiment was conducted in 2005, on a sandy clay loam Oxisoil of the "Formação Barreiras" in Cabo de Santo Agostinho. The plots were outlined by metal plates inserted in the soil along the slope (1.0 m width x 3.0 length). The tests consisted of the application of four flow levels to evaluate the volume of liquid discharge and detached sediment mass. The soil detachment rate was linear to shear stress (τ). Soil erodibility (Kr) was 0.0016 kg N-1 S-1 and the critical shear stress was 4.37 Pa. The low soil erodibility value and high critical shear stress value observed at the surface of the ravines possibly resulted from a soil consolidation process induced by wetting and drying cycles. Soil erodibility (Kr) in depth varied from 0.012 to 0.070 kg N-1 S-1, depending on the clay content. The runoff flow regime in ravines was turbulent supercritical and therefore similar to rill flow, as described in the literature.