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Accurate daily rainfall estimation is required in several applications such as in hydrology, hydrometeorology, water resources management, geomorphology, civil protection, and agriculture, among others. CMORPH daily rainfall estimations were integrated with rain gauge measurements in Brazil between 2000 and 2015, in order to reduce daily rainfall estimation errors by means of the statistical objective analysis scheme (SOAS). Early comparisons indicated high discrepancies between daily rain gauge rainfall measurements and respective CMORPH areal rainfall accumulation estimates that tended to be reduced with accumulation time span (e.g., yearly accumulation). Current results show CMORPH systematically underestimates daily rainfall accumulation along the coastal areas. The normalized error variance (NEXERVA) is higher in sparsely gauged areas at Brazilian North and Central-West regions. Monthly areal rainfall averages and standard deviation were obtained for eleven Brazilian watersheds. While an overall negative tendency (3 mm·h−1) was estimated, the Amazon watershed presented a long-term positive tendency. Monthly areal mean precipitation and respective spatial standard deviation closely follow a power-law relationship for data-rich watersheds, i.e., with denser rain gauge networks. Daily SOAS rainfall accumulation was also used to calculate the spatial distribution of frequencies of 3-day rainfall episodes greater than 100 mm. Frequencies greater than 3% were identified downwind of the Peruvian Andes, the Bolivian Amazon Basin, and the La Plata Basin, as well as along the Brazilian coast, where landslides are recurrently triggered by precipitation.

This paper presents a new approach of landslides zonation hazard studies, based on an integrated study of structural data along with geomorphological and external factors, in a hilly regions of Brazil, covered by a tropical humid rain-forest, called Serra do Mar. The Serra do Mar consists of a hilly region along the east coast of Brazil, with high slopes and many geological structures in a gneiss -migmatitic terrain. In contrast to traditional approaches, this method proposes that structural data (foliation, fractures and bedding planes) and its relation with the slope geometry, is important to be consider in the landslide zonation hazard, along with declivity, relative relief, soil and rock properties, land use and vegetation cover and hydrogeological and climate factors. Results show that slopes with high hazard have the same dip direction of geological structures. Landslide zonation hazard using structural data contributes to a better understanding of how these structures, preserved in tropical residual soils, influence on slope stability and generates landslides.

Due to its meteorological, geological and geomorphological settings, Brazilian's Atlantic coast have suffered severe landslide phenomena, particularly along the cost of São Paulo, Rio de Janeiro, and Santa Catarina states. Studies have shown that these processes are complex and triggered by several factors. However, within the study area, many landslide locations are placed on gneiss migmatitic terrain with pronounced geological discontinuities. The objective of this paper is to assess landslide occurrences in Serra do Mar (Caraguatatuba, SP) and investigate, by means of kinematic analysis, how they correlate with foliation and fractures present on the rocks. Kinematic analysis is used to investigate which discontinuities are more favorable to landslides occurrence and their relationship with slope directions. Structural information and kinematic data models are used to evaluate cause-effect relationship of landslide processes. Results show that dip slopes, with NE-SW direction, have greatest potential for the occurrence of planar landslides. On the other hand, anti-dip and cross-dip slopes have a greater potential to develop wedge landslides. Rock weathering and fluid flux along foliation planes can intensify mass movement. Such effect is also seen in residual soil, since they are able to preserve relict structures of the rock. This study contributes to a better understanding of how geological structures, preserved in tropical residual soils, influence shallow landslides.

A Serra do Mar paulista, nos últimos 50 anos, passou por uma série de eventos pluviométricos intensos, que ocasionaram acidentes diversos relacionados a processos de dinâmica superficial, com consequências sociais, econômicas e ambientais catastróficas, principalmente nos municípios de Cubatão, São Sebastião e Caraguatatuba. Em 1967, ocorreu, entre Caraguatatuba e São Sebastião, um dos eventos mais excepcionais de escorregamentos generalizados associados a corridas já registrados no país. O objetivo do trabalho foi analisar atributos fisiográficos e morfométricos em relação à potencialidade de bacias hidrográficas à ocorrência de corridas de massa, na Serra do Mar do litoral norte do Estado de São Paulo. A área de estudo foi dividida em 13 unidades fisiográficas, abrangendo compartimentos de planícies; escarpas da Serra do Mar e espigões digitados; relevo de morros rebaixados e soerguidos pela Falha Camburu; relevos montanhosos e de morros com diferentes características no Planalto de Juqueriquerê; Planalto de Paraitinga na borda das escarpas da Serra do Mar; e morros, morrotes e colinas isoladas. Os resultados demonstraram que bacias hidrográficas localizadas em porções escarpadas, com alta declividade e forte estruturação das drenagens por fraturas/falhas, com vales encaixados, como a unidade fisiográfica II, apresentam maiores valores para os parâmetros morfométricos, indicando maior potencialidade à ocorrência de corridas. Portanto, a compartimentação fisiográfica e a análise dos parâmetros morfométricos possibilitaram a avaliação integrada de diferentes atributos do meio físico em relação à suscetibilidade de bacias hidrográficas à ocorrência de corridas, demonstrando que o controle estrutural na evolução geomorfológica dessas bacias é um fator fundamental tanto na distribuição de encostas com direções favoráveis à ocorrência de escorregamentos como nos resultados dos parâmetros morfométricos.