Process-based 2DH morphodynamic modeling of tidal inlets: A comparison with empirical classifications and theories

The economical and ecological importance of tidal inlets has fostered the development of empirical tools for inlet management during the last century. This study aims at confronting these empirical theories with results obtained with a process-based numerical model, MORSYS2D. This 2DH morphodynamic modeling system is applied to an idealized tidal inlet/lagoon system with different combinations of significant wave height, tidal range and tidal prism. The numerical model predictions are compared to the empirical models of Hayes, Bruun, O'Brien and FitzGerald and to morphologies observed at natural tidal inlets. The results present good accordance with observations as well as with some key behaviors predicted with the empirical theories. The predicted morphologies satisfy the relation of O'Brien between the tidal prism and the cross-sectional area, the model reproduces the conceptual model of sand by-passing by ebb-tidal delta breaching of FitzGerald and the classifications of Hayes and Bruun are generally respected. However, some inconsistencies between model results and Hayes classification highlight the limitations of applying this classification, which only considers the yearly-averaged significant wave height and tidal range, to a single tidal inlet case.     

Deposition and tectonic setting of the Palaeoproterozoic Castelo dos Sonhos metasedimentary formation,Tapajós Gold Province,Amazonian Craton,Brazil: age and isotopic constraints

The Castelo dos Sonhos Formation (CSF) represents a relic of a sedimentary basin located in the southeastern Tapajós Gold Province (TGP), at its boundary with the Iriri–Xingu Domain (IX), south of the Amazonian Craton. The formation comprises mature, coarse-grained metasandstones (quartz-arenites) intercalated with auriferous metaconglomerates with clasts of quartz and subordinately of banded iron formation, quartzite, schist, and felsic metavolcanic rocks. Lithology, planar, channelled, and large-scale cross-bedding suggest deposition in continental setting by the braided fluvial system associated with alluvial fans and subordinate aeolian dunes. The rocks underwent very low metamorphism and gently synformal folding, and were intruded by andesites and granitoids (2011–1918 Ma). U–Pb LA-ICP-MS zircon data indicate maximum depositional ages of 2050 Ma (metaconglomerate) and 2074, 2088, and 2104 Ma (metasandstones). Hence, deposition occurred at 2050–2011 Ma, slightly preceding or being coeval with the onset of the orogenic phase in TGP (2030–1956 Ma). The quartz-arenite composition, zircon U–Pb data, and negative εHf (?1.3 to ?13.0) and εNd (?2.9 to ?5.3) values indicate: (1) quartzose provenance, (2) prolonged transport and recycling of sedimentary sources, (3) multiple age peaks (2050–3700 Ma), with predominant sources of 2100 and 2750 Ma, and (4) long crustal residence time for the source rocks. Source areas were Rhyacian–Siderian orogenic belts to Mesoarchaean terranes of the Amazonian Craton located to the east, southeast, and northeast of TGP, along with Palaeoarchaean and Eoarchaean detrital zircons recycled from older sedimentary rocks. We interpret CSF as part of a larger foreland system related to the evolution of Rhyacian orogens, currently represented by the Bacajá and Santana do Araguaia domains. The present location of CSF in the easternmost TGP, close to its boundary with IX, is due to rifting (1.89–1.80 Ga) that produced the Uatumã Silicic Large Igneous Province (Uatumã SLIP), and the juxtaposition of the crustal domains is supported by gravity data.     

The Varre-Sai chondrite,a Brazilian fall: petrology and geochemistry

The Varre-Sai meteorite fell along the border of the states of Espirito Santo and Rio de Janeiro, Brazil; on 19 June 2010 at 5:40 pm. Petrography and X-ray powder diffraction (XRD) indicate that the rock is an L5 S4 chondrite, with blastoporphyritic texture that has not been previously described. Geochemical data based on major and rare-earth elements (REEs) show that Varre-Sai is highly similar to the other L chondrites. In Harker diagrams, Varre-Sai, L, and LL chondrites form a single group, suggesting no significant chemical differences between them and contributing to the long-standing debate of whether LL chondrites form a distinct group or whether they are a subset of the L group. Harker diagrams also define a trend from E to H and L/LL chondrites, similar to the cosmochemical trends suggested by other authors. The behaviour of Fe₂O_3t and NiO indicates a relationship with Fe-Ni alloys, and their trend in the diagram suggests some chemical differentiation in the ordinary chondrite parental bodies. The REE content in Varre-Sai, normalized to C chondrites, falls in the field of L chondrites and others, but with slight REE enrichment. The chemical differences in chondrites, mainly in REEs, Fe₂O_3t and NiO could be alternatively interpreted as variations in the inherited agglutinated materials as chondrules, Ca–Al-rich inclusions and Fe–Ni nodules.     

The Disruption Index (DI) as a tool to measure disaster mitigation strategies

Apart from the loss of lives, injuries and homeless resulting from an earthquake, not only the economy and physical landscape are altered, but also the lives of citizens and their places of work are dramatically altered. If critical services and functions are disrupted for more than a reasonable time period, consequences can be severe. All communities are at risk and face potential disaster, if unprepared. The Disruption Index (DI) is a tool that allows the representation of a complex and multidimensional situation in a concise and easier way, providing institutions and communities with a way to identify the global earthquake impact in a geographical area, the elements at risk, and the means to reduce it. In the present paper, after a short review of the concept of DI, its geographic (spatial) distribution is developed and an application to some cities in Algarve (Portugal) is made. Then, the use of DI in the context of measuring the risk reduction for alternative disaster mitigation strategies is introduced and illustrations are presented.     

QuakeIST<Superscript>®</Superscript> earthquake scenario simulator using interdependencies

Earthquakes are a permanent threat to urban environments worldwide. The communication of the related risk demands accurate damage model simulations and an interactive visualization of results. The aim of this paper is to provide a realistic problem-solving environment for earthquake discussions among decision makers, stakeholders, and the general public. QuakeIST^® is an integrated earthquake simulator developed by Instituto Superior Técnico (Lisbon University), oriented towards the performance of risk calculations concerning damage propagations that use the Disruption Index concept. This software imports data stored in a GIS environment, handles different ground motion scenarios, and deals with a complex situation of different soils and vulnerabilities of various layers of civil structures (buildings, lifelines, and other urban structures). It models interdependencies between several infrastructures and between infrastructures and the urban tissue. The computer programme is very versatile, written in separate modules, allowing an experimented user to incorporate new formulations. Results can be treated with any statistical application and most common GIS commercial environments can produced their geographic visualization. Current progress and new upcoming are briefly described at the end of the paper.     

Exploring self-affine properties in seismograms

Self-affine properties have been observed in a large variety of rough profiles and time series from natural data sets. In this work, seismograms used for oil prospecting, which contain information of distinct subsurface features collected by seismic waves reflected or scattered at their interfaces, are taken into consideration. It is expected that any self-affine property, measured by the Hurst exponent H, depends on the depth. For each seismic trace, H is evaluated locally within a moving window, which is chosen narrow enough to reveal space dependency but also wide enough to display scale invariance. With the use of color code diagrams, it is possible to draw two-dimensional diagrams that show the local dependence of H for the analyzed seismogram. The reliability of the method is tested by the investigation of seismograms that contain ground roll components, as well as multiple reflections. The effect of different kinds of filter in the scaling properties is also investigated. In this case, comparisons are drawn among the diagrams obtained from original seismograms and those subjected to appropriate filter to eliminate spurious components. Work supported by the Brazilian agencies CNPq, FINEP-CTPETRO and Petrobras.     

Emerging trends in urbanizing Palestine: neglected city-builders beyond the occupation

In this article, we draw attention to trends in land transformation in the West Bank since the Second Intifada, after which a surge of investment from Gulf countries entered Palestine, almost exclusively in the West Bank. The occupied Palestinian territories have attracted a great deal of attention from media and academics, yet the vast majority of scholarship focuses on the conflict and the variety of social, economic, and political repercussions of the on-going Israeli occupation. While the occupation has undeniably serious impacts on every aspect of life for Palestinians, the near-exclusive focus on the conflict means that significant new trends, such as urban mega-developments and emerging market-based urbanisation processes, have been largely overlooked. We outline three directions for future research: the assemblage of “neglected city-builders” shaping current urbanization processes in Palestine; the ideas, policies, and norms circulating in the West Bank; and the social, spatial, economic, and other impacts of these new urban developments.     

Forest Fire Alert System: a Geo Web GIS prioritization model considering land susceptibility and hotspots – a case study in the Carajás National Forest,Brazilian Amazon

To increase the monitoring potential of forest fires, an alert classification methodology using satellite-mapped hotspots has been established to help forest managers in the prioritization of which hotspot to be verified in the field, thus potentially improving the distribution of fire-fighting resources. A computer application was developed based on web-distributed geographical information technology whose main function is to interact automatically generated satellite hotspots and risk areas indicated in fire-susceptibility maps and classify them into five alert levels. The location of the hotspots is available continuously every 4 h, and a susceptibility map is produced daily through map algebra algorithm, which uses static (topography, vegetation and land use) and dynamic (weather) variables. Every process runs through automated geoprocessing routines. The methodology was tested during the dry period of 2007 in the Carajás National Forest, in the Brazilian Amazon, within an area of 400,000 ha. It is a critical area constantly threatened by fires caused by invasions and deforestation owing to intense agribusiness advances and mining activities in its surroundings. This situation results in observations of many hotspots inside the study area for the same day and almost the same time period, in places of extreme opposites, demanding complex rapid analysis and hindering the decision of the displacement of fire-fighting teams. Further, a major mining company operates within the National Forest area, maintaining actions of protection as part of its environmental mining license. Results are presented under three aspects: (i) the credibility of the daily susceptibility map (algorithm), which showed strong correlation between areas of greatest risks and the confirmed forest fires; (ii) the reliability of hotspots (alert levels), confirming 71% of fires; (iii) accuracy in the decision of which hotspot to be checked, which revealed the same number of verifications at different alert levels, 82% confirmed alert 5 hotspots (maximum) and only 50% from alert 1 (minimum), resulting in faster fire-fighting actions, minimizing burned areas and, in some cases, allowing fire control before its spreading. Therefore, the methodology demonstrated that GIS routines are able to determine the relationship between a reality-based, interpreted susceptibility map of the area and satellite-generated hotspots, highlighting the ones of highest hazard level through the alert classification, becoming an important tool to help decisions from the fire-control center, especially for high-risk regions. The methodology may be extrapolated to other forested areas.