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1.
Natural Hazards - A landslide is a geomorphological hazard with significant ecological and economic damages. The present study aimed to identify landslide-prone areas in Farizi watershed via the... 相似文献
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Cavalcante Marianna Rodrigues Gullo da Cunha Luz Barcellos Priscila Cataldi Marcio 《Natural Hazards》2020,100(3):1117-1136
Natural Hazards - Flooding and water logging possess severe hazards to human population in many parts of the world. Mumbai, the study area, is one of the cities in India and has been frequently... 相似文献
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José Tasso Felix Guimarães Prafulla Kumar Sahoo Mariana Maha Jana Costa De Figueiredo Karen da Silva Lopes Markus Gastauer Silvio Junio Ramos Cecilio Frois Caldeira Pedro Walfir M. Souza-Filho Luiza Santos Reis Marcio Sousa Da Silva Paulo Rogenes Pontes Renato Oliveira Da Silva Junior Tarcísio Magevski Rodrigues 《第四纪科学杂志》2021,36(2):255-272
This study addresses paleoclimate influences in a southern Amazonia ecotone based on multiproxy records from lakes of the Carajás region during the last 45k cal a bp. Wet and cool environmental conditions marked the initial deposition in shallow depressions with detrital sediments and high weathering rates until 40k cal a bp. Concomitantly, forest and C3 canga plants, along with cool-adapted taxa, developed; however, short drier episodes enabled expansion of C4 plants and diagenetic formation of siderite. A massive event of siderite formation occurred approximately 30k cal a bp under strong drier conditions. Afterwards, wet and cool environmental conditions returned and persisted until the Last Glacial Maximum (LGM). The LGM was marked by lake-level lowstands and subaerial exposure. The transition from the LGM to the Holocene is marked by the onset of oscillations in temperature and humidity, with an expansion of forest and canga plants. Cool taxa were present for the last time in the Carajás region ~ 9.5–9k cal a bp. After 10k cal a bp , shallow lakes became upland swamps due to natural infilling processes, but the current vegetation types and structures of the plateaus were acquired only after 3k cal a bp under wetter climatic conditions. 相似文献
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Harm Jan Pierik Jelle I. M. Moree Karianne M. van der Werf Lonneke Roelofs Marcio Boechat Albernaz Antoine Wilbers Bert van der Valk Marieke van Dinter Wim Z. Hoek Tjalling de Haas Maarten G. Kleinhans 《Sedimentology》2023,70(1):179-213
In the transformation from tidal systems to freshwater coastal landscapes, plants act as eco-engineering species that reduce hydrodynamics and trap sediment, but nature and timing of the mechanisms of land creation along estuaries remains unclear. This article focuses on the Old Rhine estuary (The Netherlands) to show the importance of vegetation in coastal landscape evolution, predominantly regarding tidal basin filling and overbank morphology. This estuary hosted the main outflow channel of the river Rhine between ca 6500 to 2000 cal bp , and was constrained by peat during most of its existence. This study reconstructs its geological evolution, by correlating newly integrated geological data and new field records to varying conditions. Numerical modelling was performed to test the inferred mechanisms. It was found that floodbasin vegetation and resulting organic accumulation strongly accelerated back-barrier infill, by minimizing tidal influence. After tidal and wave transport had already sufficiently filled the back-barrier basin, reed rapidly expanded from its edges under brackish conditions, as shown by diatom analysis and datings. Reed growth provided a positive infilling feedback by reducing tidal flow and tidal prism, accelerating basin infilling. New radiocarbon dates show that large-scale crevassing along the Old Rhine River – driven by tidal backwater effect – only started as nutrient-rich river water transformed the floodbasin into an Alder carr in a next phase of estuary evolution. Such less dense vegetation promotes crevassing as sediments are more easily transported into the floodbasin. As river discharge increased and estuary mouth infilling progressed, crevasse activity diminished around 3800 to 3000 cal bp , likely due to a reduced tidal backwater effect. The insights from this data-rich Holocene study showcase the dominant role that vegetation may have in the long-term evolution of coastal wetlands. It provides clues for effective use of vegetation in vulnerable wetland landscapes to steer sedimentation patterns to strategically adapt to rising water levels. 相似文献
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Ferreira Breno S. Almeida Marcio S. S. Lopes Francisco R. Reis Cavalcanti Maria do Carmo Pires Filho Celso José 《Geotechnical and Geological Engineering》2022,40(4):1973-1987
Geotechnical and Geological Engineering - The Manso Dam, in the Brazilian State of Mato Grosso, intended for flood control and electricity generation, was built by a state-owned energy company in... 相似文献
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Galactic X-ray emitters have been described by Giovannelli andSabau-Graziati (1993). We would address the bulk of this paper on HighMass X-Ray Binaries (HMXBs) and particularly in demonstrating theimportance of these systems as powerful laboratories to test the propertiesof high-energy physical processes through the multi-frequency studies oftheir behavior. Interactions between the two components of those systemsoriginate processes that manifest themselves along a large part of theelectromagnetic spectrum. Therefore it is possible to study indirectlyhigh-energy phenomena through the analysis oflow-energy phenomena with enormous advantages since the latter can bemainly studied via ground-based experiments, meanwhile the former can bestudied only by mean of space-based experiments, at least up to energiesof order 100 GeV.Moreover, since HMXBs are galactic, their emissions are the highestmeasurable; this renders such systems the most powerful laboratories to testtheories on collapsed objects, which can be scaled to extra-galactic distancesand dimensions. This fact suggests that HMXBs can be in general useful targetseven for small satellites, and in particular, in the X-ray energy range,very suitable targets for experiments like SIXE (Spanish Italian X-rayExperiment) to be launched in small satellites such as the Spanish MINISAT-02. 相似文献
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Douglas C Morton Marcio H Sales Carlos M SouzaJr Bronson Griscom 《Carbon balance and management》2011,6(1):18
Background
Historic carbon emissions are an important foundation for proposed efforts to Reduce Emissions from Deforestation and forest Degradation and enhance forest carbon stocks through conservation and sustainable forest management (REDD+). The level of uncertainty in historic carbon emissions estimates is also critical for REDD+, since high uncertainties could limit climate benefits from credited mitigation actions. Here, we analyzed source data uncertainties based on the range of available deforestation, forest degradation, and forest carbon stock estimates for the Brazilian state of Mato Grosso during 1990-2008. 相似文献9.
Jos María Viramonte Raúl Alberto Becchio Jos Germn Viramonte Marcio Martins Pimentel Roberto Donato Martino 《Journal of South American Earth Sciences》2007,24(2-4):167-183
New field, petrological, geochemical, and geochronological data (U–Pb and Sm–Nd) for Ordovician rock units in the southeastern Puna, NW Argentina, indicate two lithostratigraphic units at the eastern–northeastern border of salar Centenario: (1) a bimodal volcanosedimentary sequence affected by low- to medium-grade metamorphism, comprising metasediments associated with basic and felsic metavolcanic rocks, dated 485 ± 5 Ma, and (2) a plutonic unit composed of syenogranites to quartz-rich leucogranites with U–Pb zircon ages between 462 ± 7 and 475 ± 5 Ma. Felsic metavolcanic and plutonic rocks are peraluminous and show similar geochemical differentiation trends. They also have similar Sm–Nd isotopic compositions (TDM model ages of 1.54–1.78 Ga; εNd(T) values ranging from −3.2 to −7.5) that suggest a common origin and derivation of the original magmas from older (Meso-Paleoproterozoic?) continental crust. Mafic rocks show εNd(T) ranging from +2.3 to +2.5, indicating a depleted mantle source. The data presented here, combined with those in the literature, suggest Ordovician magmatism mainly recycles preexisting crust with minor additions of juvenile mantle-derived material. 相似文献
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Marcio T. A. H. Muella Eurico R. de Paula Alan A. Monteiro 《Surveys in Geophysics》2013,34(2):233-251
This paper reports differences in the occurrence statistics of global positioning system (GPS) L-band scintillations at observational sites located in the inner regions of the northern and southern crests of the equatorial ionization anomaly. Ground-based GPS data acquired at the closed magnetically aligned stations of Manaus (3.1°S; 59.9°W; dip lat. 6.2°N) and Cuiabá (15.5°S; 56.1°W; dip. lat. 6.2°S), Brazil, from December 2001 to February 2007 are used in the analysis. The drift dynamics of Fresnel-scale ionospheric irregularities at the southern station of Cuiabá are also investigated. Only geomagnetically quiet days with the sum of daily Kp < 24 were used in the analysis statistics and in the irregularity drift studies. The results reveal a clear dependence of the scintillation occurrence with the solar activity, but there exists an asymmetry in the percentage of scintillation occurrence between the two stations throughout the period analyzed. The nocturnal occurrence of the scintillations over Cuiabá is predominantly larger than over Manaus, but this scenario seems to change with the decline in the solar activity (mainly during local post-midnight hours). A broad minimum and maximum in the scintillation occurrence appears to occur over both the stations, respectively, during the June solstice (winter) and December solstice (summer) months. The dynamics of the Fresnel-scale irregularities, as investigated from the estimations of the mean zonal drift velocities, reveals that the amplitude of the eastward drifts tends to reduce with the decline in the solar activity. The magnitude of the zonal drift velocities during the December solstice months is larger than during the equinoxes, with the differences being more pronounced at solar maximum years. Other relevant aspects of the observations, with complementary data from a low-latitude ionospheric model, are highlighted and discussed. 相似文献