Urban social vulnerability assessment with physical proxies and spatial metrics derived from air- and spaceborne imagery and GIS data

Risk management in urban planning is of increasing importance to mitigate the growing amount of damage and the increasing number of casualties caused by natural disasters. Risk assessment to support management requires knowledge about present and future hazards, elements at risk and different types of vulnerability. This article deals with the assessment of social vulnerability (SV). In the past this has frequently been neglected due to lack of data and assessment difficulties. Existing approaches for SV assessment, primarily based on community-based methods or on census data, have limited efficiency and transferability. In this article a new method based on contextual analysis of image and GIS data is presented. An approach based on proxy variables that were derived from high-resolution optical and laser scanning data was applied, in combination with elevation information and existing hazard data. Object-oriented image analysis was applied for the definition and estimation of those variables, focusing on SV indicators with physical characteristics. A reference Social Vulnerability Index (SVI) was created from census data available for the study area on a neighbourhood level and tested for parts of Tegucigalpa, Honduras. For the evaluation of the proxy-variables, a stepwise regression model to select the best explanatory variables for changes in the SVI was applied. Eight out of 47 variables explained almost 60% of the variance, whereby the slope position and the proportion of built-up area in a neighbourhood were found to be the most valuable proxies. This work shows that contextual segmentation-based analysis of geospatial data can substantially aid in SV assessment and, when combined with field-based information, leads to optimization in terms of assessment frequency and cost.     

Estimation of regional-scale groundwater flow properties in the Bengal Basin of India and Bangladesh

Quantitative evaluation of management strategies for long-term supply of safe groundwater for drinking from the Bengal Basin aquifer (India and Bangladesh) requires estimation of the large-scale hydrogeologic properties that control flow. The Basin consists of a stratified, heterogeneous sequence of sediments with aquitards that may separate aquifers locally, but evidence does not support existence of regional confining units. Considered at a large scale, the Basin may be aptly described as a single aquifer with higher horizontal than vertical hydraulic conductivity. Though data are sparse, estimation of regional-scale aquifer properties is possible from three existing data types: hydraulic heads, ¹⁴C concentrations, and driller logs. Estimation is carried out with inverse groundwater modeling using measured heads, by model calibration using estimated water ages based on ¹⁴C, and by statistical analysis of driller logs. Similar estimates of hydraulic conductivities result from all three data types; a resulting typical value of vertical anisotropy (ratio of horizontal to vertical conductivity) is 10⁴. The vertical anisotropy estimate is supported by simulation of flow through geostatistical fields consistent with driller log data. The high estimated value of vertical anisotropy in hydraulic conductivity indicates that even disconnected aquitards, if numerous, can strongly control the equivalent hydraulic parameters of an aquifer system.     

Strontium stable isotopes fractionate in the soil environments?

This study shows that the stable isotopic composition of strontium (the ⁸⁸Sr/⁸⁶Sr ratio expressed as δ^88/86Sr value relative to the NBS987 standard) varies significantly in sedimentary terrestrial environments. The abundances of ⁸⁶Sr, ⁸⁸Sr isotopes were analyzed by MC-ICP-MS “Nu Plasma”. All studied rocks and waters show δ^88/86Sr values that are distinctly different from the measured NBS987 standard (yielding 0.01 ± 0.05‰, all errors are reported as 2σ). Modern corals from the northern Gulf of Aqaba, Red Sea yielded significantly different value than seawater (δ^88/86Sr = 0.22 ± 0.07‰, compared to 0.35 ± 0.06‰, respectively), in an excellent correlation with the δ^88/86Sr analyses reported by Fietzke and Eisenhauer [Fietzke, J., Eisenhauer, A., 2006. Determination of temperature-dependent stable strontium isotopes (⁸⁸Sr/⁸⁶Sr) fractionation via bracketing standard MC-ICP-MS. Geochm. Geophys. Geosyst. 7 (no. 8)] on other coral samples. All carbonate samples that originated in the marine environment: corals (porites and acropora from the northern Gulf of Aqaba); Cretaceous limestone and runoff from the Judea Mountains as well as lacustrine evaporitic aragonite (Dead Sea); and Red Sea and Atlantic seawater yield an average δ^88/86Sr value of 0.26 ± 0.1‰. On the other hand, secondary materials (products of chemical weathering) from the terrestrial environment of the Judea Mountain such as terra rossa soil and speleothem calcite (that derives its Sr from the above-lying soil) yielded significantly lower δ^88/86Sr value of − 0.17 ± 0.06‰. This indicates that strontium isotopes fractionate in the soil environment calling for a possible development of strontium isotopes as a tracer for processes of chemical weathering and pedogenesis.     

Trajectory Studies of Polar Stratospheric Cloud Lidar Observations at Sodankylä (Finland) During SESAME: Comparison with Box Model Results of Particle Evolution

Polar stratospheric clouds (PSC) were observed with the multi-wavelength lidar of the MOANA project (Modelling and Observations of Aerosols in the Northern Atmosphere) during SESAME (Second European Stratospheric Arctic and Mid-latitude Experiment). The physical state, liquid or solid, of the cloud particles can be inferred from the lidar data. Using isentropic back-trajectories to obtain the thermal history of the sampled air masses, it is possible to reconcile most of the observations with current ideas on PSC formation and evolution. When the cloud particles were identified as liquid, changes in the size distribution of the droplets along the trajectory were calculated using a micro-physical box model. Backscatter ratios calculated from the size distributions are in broad agreement with the lidar data, giving confidence in current understanding of the evolution of ternary solution (H2SO4, HNO3 and H2O) droplets.Results from two soundings are shown which bear on the problem of the formation of solid particles. In the first, solid particles were detected. The air mass had cooled to the frost point 12 hours earlier. In the second no solid particles were detected although the air temperature was below the nitric acid trihydrate existence point, and had decreased by 12K in the previous 14 hours.     

Clay-mineral and grain-size distributions in surface sediments of the White Sea (Arctic Ocean): indicators of sediment sources and transport processes

In this study, the grain-size and clay-mineral compositions of 73 surface sediment samples collected in a variety of environmental settings in the White Sea are presented to characterize recent sedimentation processes, reconstruct transport pathways, and identify potential source areas of the terrigenous components. Areas >100 m deep are invariably characterized by silty clay, whereas areas <100 m deep exhibit more heterogeneous grain-size compositions plausibly explained by coastal erosion and (re-)distribution mechanisms, particularly tidal currents. The dominance of sand in the estuarine areas of the Onega and Dvina rivers as well as toward the Gorlo Strait connecting the White Sea with the Barents Sea is attributed to increased current speeds. Illite and smectite are the dominant clay minerals in recent sediments of the southwestern and eastern White Sea sectors, respectively. Their distribution patterns largely depend on the geology of the source areas, and mirror surface circulation patterns, especially in Dvina Bay. Smectite is a key clay mineral in White Sea surface sediments, as it reveals the dominating influence of the Northern Dvina’s runoff on sedimentation and water circulation throughout the basin. In comparison to other Eurasian shelf seas, the White Sea is characterized by a greater diversity of clay-mineral assemblages, which range from illite- to smectite-dominated sectors containing variable amounts of chlorite and kaolinite.     

Contemporary archaeomagnetic results and the accuracy of archaeomagnetic dates

When multiple archaeomagnetic samples are collected from the same site or component, it is tempting to look for evidence of temporal differences between the collected features. This paper addresses the issue of the practical limits to confidently identifying temporal differences based on archaeomagnetic sample information. Three controlled data sets suggest that when the specimen polar projections of the samples compared have substantially overlapping ranges and when sample mean projections are less than five degrees apart, statistical comparisons do not support conclusions about probable age differences. These results suggest that temporal differences less than 50 to 100 years (depending on the rate of directional change in the geomagnetic field) between features within a site or component will be difficult to confidently identify. Additional analysis leads to the hypothesis, however, that the averaged results from sets of archaeomagnetic samples might provide the basis for making fine scale temporal distinctions between sites or components from which multiple archaeomagnetic samples have been collected.     

Geochemistry, tectonic setting and geodynamic significance of late orogenic dikes in the Melibocus Massif, Bergsträsser Odenwald

Summary The Melibocus Massif forms a tonalite pluton in the W’ Bergstr?sser Odenwald, which is interpreted as part of a magmatic arc of Devonian to Carboniferous age. Dikes of various compositions intrude frequently this tonalite. Different dike-lithologies are associated with different strike directions. Most dikes show evidence of high-temperature shearing. A probable maximum paleostress direction of ca. 060° can be estimated, i.e. nearly parallel to the known Variscan subduction zone in the Northwest. Due to their ductile deformation under conditions around the Ar-closing temperature of amphibole, intrusion likely occurred during the Carboniferous (Mississippian). The gabbroic to dioritic dikes (malchites) have calc-alkaline composition. Comparison with modern analogues suggests subduction-related arc magmatism. Rare earth element distributions indicate more than 5% partial melting of the mantle source with limited amounts of residual garnet. In contrast to the tonalite pluton the granitoid dikes (alsbachites) are of S-type origin, as indicated by primary muscovite and chemical composition. This requires involvement of continental material in the dike’s source rather than in the tonalite host rock’s source. The trace element chemistry of these dikes indicates magma formation in a convergent plate tectonic situation, i.e. a magmatic arc regime. Therefore, the dikes are probably the late part of the same subduction-related magmatism, which produced the tonalitic and other plutons of the Bergstr?sser Odenwald. In contrast to the large pluton-forming magmas, formation of the dikes during late or post-collisional extension or transtension followed by a phase of compression or transpression is probable.

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Zusammenfassung Geochemie, tektonische Stellung und geodynamische Signifikanz sp?torogener G?nge im Melibocus Massiv, Bergstr?sser Odenwald Der Melibokus Tonalit-Pluton geh?rt zum Bergstr?sser Odenwald, der als Teil eines devonisch-karbonischen magmatischen Bogens interpretiert wird. In diesem Pluton treten sehr h?ufig magmatische G?nge unterschiedlicher Zusammensetzung auf. Die Arbeit zeigt, dass die G?nge unterschiedlicher Zusammensetzung unterschiedliche Streichrichtungen haben. Die meisten der untersuchten G?nge zeigen Hochtemperatur-Schergefüge. Aus der Lage der zerscherten G?nge l?sst sich eine Pal?ostressrichtung mit 060° für Sigma 1 ableiten. Diese Richtung weicht nur unwesentlich von der bekannten variskischen Subduktionszone im Nordwesten ab. Aufgrund ihrer Hochtemperatur-Gefüge, die im Bereich der Schlie?ungstemperatur von Ar in Hornblenden gebildet wurden, ist das Alter der G?nge wahrscheinlich ebenfalls als Karbon (Mississippian) einzustufen. Die gabbroiden bis dioritischen G?nge (Malchite) haben eine kalkalkaline Zusammensetzung. Der Vergleich mit rezenten Magmatiten deutet auf eine Entstehung in einem magmatischen Bogen (Kontinentalrand) hin. Die Seltenerdelementverteilung der G?nge zeigt einen wahrscheinlichen Aufschmelzungsgrad der Mantelquellregion von über 5% bei einem geringen Anteil von residualem Granat an. Im Gegensatz zu den tonalitischen Nebengesteinen zeigen die granitoiden G?nge anhand ihrer modalen (Muskovit) als auch chemischen Zusammensetzung S-Typ-Charakter. Dies bedeutet eine h?here Beteiligung krustaler Komponente in der Magmenquelle als dies für den Tonalit angenommen werden darf. Die Spurenelementchemie der granitoiden G?nge zeigt ebenfalls eine Bildung in einem konvergenten plattentektonischen Regime, d.h. innerhalb eines magmatischen Bogens. Die G?nge stellen somit vermutlich das Produkt eines sp?ten Abschnittes des subduktionsbezogenen Magmatismus, der auch die Tonalite und andere Plutone im zentralen Bergstr?sser Odenwald geschaffen hat, dar. Im Gegensatz zu dem Magmatismus der die Plutone erzeugt hat, sind die G?nge wahrscheinlich gegen Ende der Kollision oder nachfolgend auf diese in eine sich dehnende Kruste intrudiert und in einem nachfolgenden kompressiven Regime deformiert worden.

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Received August 31, 1999; revised version accepted October 9, 2000     

The magnetic effects of brecciation and shock in meteorites: III. The achondrites

We present results of a magnetic survey of achondritic meteorites, representing the aubrites (A), diogenites (D), Irowardites (H), and eucrites (E) groups and relate their magnetic behavior to respective class characteristics and models of origin.Magnetic susceptibility (x) values cluster well within each group and decrease systematically between groups (from 2 to 0.1×10^–3GOe^–1 cm^–3), with the average metal contents, (from 1 to <0.1 wt%) in the above order. The natural remanent magnetization (NRM) values range broadly within each group, but group averages decrease roughly as above. However, the considerable within-sample and intra-group variability in NRM level and its demagnetization characteristics attest to inhomogeneous and localized brecciation effects. Although petrological-chemical studies resolve a primary component of magmatic differentiation on the planetoid of origin, no clear magnetic record of such event has been preserved. The magnetization of achondrites is mainly the product of their complex, multi-stage impact brecciation and metamorphism history, in accord with other lines of evidence.The magnetic behavior of achondrites is remarkably similar to that characteristic of lunar breccias and impact-melt rocks and reinforces their analogous mode of genesis, as brought out by chemical and petrographic analyses.     

Farm-Level Adaptation to Climatic Variability and Change: Crop Diversification in the Canadian Prairies

Among other foci, recent research on adaptation to climatic variability and change has sought to evaluate the merit of adaptation generally, as well as the suitability of particular adaptations. Additionally, there is a need to better understand the likely uptake of adaptations. For example, diversification is one adaptation that has been identified as a potential farm-level response to climatic variability and change, but its adoption by farmers for this reason is not well understood. This paper serves two purposes. The first is to document the adoption of crop diversification in Canadian prairie agriculture for the period 1994–2002, reflect upon its strengths and limitations for managing a variety of risks, including climatic ones, and gauge its likely adoption by producers in response to anticipated climate change. The second purpose is to draw on this case to refine our current understanding of climate change adaptation more generally. Based upon data from over 15 000 operations, it was determined that individual farms have become more specialized in their cropping patterns since 1994, and this trend is unlikely to change in the immediate future, notwithstanding anticipated climate change and the known risk-reducing benefits of crop diversification. More broadly, the analysis suggests that suitable and even possible climate change adaptations need to be more rigorously assessed in order to understand their wider strengths and limitations.