Reducing hazard vulnerability through local government engagement and action

The concept of a natural hazard is a human construct. It is the interaction with human communities and settlements that defines a natural phenomenon as a natural hazard. Thus the end point of hazard mitigation and hazard vulnerability assessment must involve an attempt to reduce, or mitigate, the impact of the natural hazard on human communities. The responsibility to mitigate hazard impact falls primarily upon governments and closely connected non-government and private institutional agencies. In particular, it is most often local government that takes the responsibility for safeguarding its own communities, infrastructure and people. Hazard vulnerability of specific local communities is best assessed by the local government or council, which then faces the responsibility to translate that assessment into community education and infrastructural safeguards for hazard mitigation. This paper illustrates the process of local government engagement in hazard mitigation in Australia, through the Natural Disaster Risk Management Studies, as a first step towards natural disaster reduction.     

Field Measurement of Suction, Water Content, and Water Permeability

This paper presents a review of techniques for field measurement of suction, water content, and water hydraulic conductivity (permeability). Main problems in the use of field tensiometers are addressed and hints on how to improve tensiometer performance are given. Advantages and limitations of instruments for indirect measurement of suction including electrical conductivity sensors, thermal conductivity sensors, dielectric permittivity sensors, filter paper, and psychrometer are discussed. Techniques for water content measurement based on dielectric methods are then presented. These include time and amplitude domain reflectometry and capacitance. Finally, a brief overview of methods for measurement of water permeability in the field is presented.     

贵州遵义牛蹄塘组黑色岩系的硒同位素变化及其环境指示初探

西南早寒武世牛蹄塘组是分布在中国南方扬子地台的一套黑色岩系,区域上发育有典型富集多金属元素的硫化物矿化层.选取遵义松林小竹牛蹄塘组下部富硒、钼、镍等元素的黑色岩系剖面,利用Se同位素初步探讨了该剖面岩石的沉积环境和硒的可能来源.结果表明,小竹牛蹄塘组下部剖面黑色岩系的δ82/76SeSRM3149比值变化较大,下部底层含碳斑脱岩与磷块岩的变化范围在-4.35‰～ 4.11‰之间;中间镍钼层及碳质页岩、碳质碳酸盐岩的δ82/76SeSRM3149变化范围窄,平均值为0.9‰±0.23‰(n=4);上层碳质页岩为-1.24‰.结合已发表的钼同位素数据,认为中间岩石沉积于缺氧/无氧环境,但存在盆地海水与热液或充氧水团的混合;下层的岩石曾一度位于充氧与贫氧环境的边界面,局部岩石曾暴露地表经历了较强的风化和蚀变作用,海水中硒有可能来自底部富硒斑脱岩的氧化淋滤或海底热液.据此推测遵义松林小竹牛蹄塘组下部岩石的沉积环境极可能处在局限盆地靠近陆地的边缘部分,经历了充氧→贫氧→缺氧/无氧→贫氧的演化阶段.     

A calculation of the large scale three dimensional distribution of diabatic heating in the atmosphere

Summary The large scale three-dimensional diabatic heating in the atmosphere is computed at 12 isentropic surfaces for a particular twelve hour time period. Using a method due toErtel, the continuity equation is combined with the equations of motion to give an explicit relation between diabatic heating and changes in potential vorticity and stability along isentropic surface trajectories. The results are barely of useful accuracy and reliability and this only under favorable conditions. The distribution of diabatic heating is qualitatively reasonable in the regions near the tropopause, close to the ground, above a cloud or moist layer, and within an area of general condensation. Errors and approximations make the computed values completely unreliable in areas of large anticyclonic vorticity or large baroclinity. Comparison of magnitudes with those computed from rainfall observations and with those measured directly at the earth's surface shows agreement in sign and within a factor of three in the areas of best data. The results emphasize that there are regions and periods where diabatic heating in the free atmosphere may be important in controlling atmospheric behavior. Sample calculations in one of these regions using values of diabatic heating computed by this study illustrate that this process is of comparable importance with the adiabatic process in determining vertical velocity.

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Zusammenfassung Die großräumige nichtadiabatische Erwärmung der Atmosphäre in 12 isentropen Flächen während eines 12stündigen Zeitabschnittes wird berechnet. Unter Verwendung einer Methode vonErtel liefert eine Kombination der Kontinuitätsgleichung mit den Bewegungsgleichungen eine explizite Beziehung zwischen der nichtadiabatischen Erwärmung, der potentiellen Vorticity und der Stabilität entlang der isentropen Trajektorien. Das Resultat ist von beschränkter Genauigkeit — und auch dies nur unter günstigen Bedingungen. Qualitativ brauchbare Verteilungen der nichtadiabatischen Erwärmung erhält man nahe der Tropopause, in Bodennähe, über einer Schicht von Wolken oder feuchter Luft und innerhalb der Zonen mit verbreiteter Kondensation. In Gebieten mit großer antizyklonaler Vorticity oder großer Baroklinität werden die berechneten Werte infolge von Meß- und Approximationsfehlern völlig ungenau. In den Gebieten mit optimalen Voraussetzungen stimmen die berechneten Werte mit den aus Niederschlagsmessungen abgeleiteten oder am Boden direkt beobachteten im Vorzeichen und innerhalb eines Faktors von 3 überein. Die Ergebnisse der vorliegenden Untersuchung weisen erneut darauf hin, daß in manchen Gebieten bzw. Zeitabschnitten das Verhalten der freien Atmosphäre durch nichtadiabatische Erwärmung wesentlich beeinflußt sein kann. Stichprobenweise Berechnungen für eines dieser Gebiete zeigen, daß die theoretisch ermittelte nichtadiabatische Erwärmung für die resultierende Vertikalgeschwindigkeit der Luft quantitativ von ähnlicher Bedeutung ist wie der adiabatische Prozeß.

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Résumé L'auteur a calculé le réchauffement non adiabatique, à grande échelle, de l'atmosphère à 12 niveaux isentropes pendant un intervalle de 12 heures. Une méthode établie parErtel combine l'équation de continuité et les équations de mouvement et aboutit à une relation explicite entre le réchauffement non adiabatique, la vorticity potentielle et la stabilité le long de trajectoires isentropes. Le résultat n'a qu'une exactitude approchée, et cela dans des conditions favorables seulement. On obtient une répartition utilisable du réchauffement non adiabatique au voisinage de la tropopause, du sol, au-dessus d'une couche de nuages ou d'air humide, ainsi qu'à l'intérieur des zones à forte condensation. Dans les régions à grande vorticity anticyclonique et à grande baroclinité, les valeurs calculées deviennent tout à fait inexactes par suite d'une approximation insuffisante et d'erreurs de mesure. Dans les régions à conditions favorables par contre, les valeurs calculées correspondent à celles que l'on peut tirer de la mesure des précipitations ou de celles que l'on mesure au sol, cela au signe et à un facteur 3 près. Le résultat de cette étude montre à nouveau que dans certaines régions ou certains laps de temps l'état de l'atmosphère peut être notablement conditionné par un réchauffement non adiabatique. Des épreuves faites pour l'une de ces régions montrent que le réchauffement non adiabatique obtenu par calcul est quantitativement aussi important pour la vitesse verticale résultante de l'air que le processus adiabatique.

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With 7 Figures     

Basalt from Louisiana continental shelf

A basalt outcrop was discovered on Alderdice Bank on the outer Louisiana continental shelf. The basalt shows an age of 76.8 ± 3.3 × 10⁶ years. Textural, mineralogical, and chemical characteristics indicate that it is an alkali basalt of shallow intrusive origin. It was probably brought to the seafloor by salt tectonics and exposed due to salt dissolution.An accurate account of the Mesozoic geologic history of the Gulf of Mexico must consider the apparent consanguinity of all magmatic rocks of the region, including the Alderdice Bank basalt, and the apparent basinward decrease in age of magmatic activities.     

Modification of an acoustic pinger to transmit temperature data

An acoustic pinger can be modified to transmit two pings per second with the delay time between pings controlled by the temperature of an external thermistor. The precision of the temperature measurements is on the order of 0.1°C. This modification does not interfere with the normal depth indicating function of the pinger and is an inexpensive means of obtaining water temperature data.