Vulnerability of farm water supply systems to volcanic ash fall

Agriculture is critically dependent on continuity of water quality and quantity. It is well-established that even small quantities of volcanic ash can disrupt municipal water supplies, with known impacts to quality including: acidification, increases in turbidity and ionic concentrations. In addition, delivery systems may be blocked or damaged by hard and abrasive suspended ash and related ash-cleanup operations place extra stress on water reserves. The aim of this study was to characterise the key areas of vulnerability of farm water supplies to volcanic ashfall, and to identify management recommendations to reduce these. From literature review and case studies of farms impacted by the 1991 Pinatubo (Philippines) and 1991 Hudson (Chile) eruptions, key issues were: sedimentation of irrigation ditches and drinking water ponds, turbidity induced abrasion of sprinkler nozzles and water pumps, and damage to electric pumps (by ash on air-intakes). Building on this, we characterised the water-use regimes and water supply system vulnerability of eight case-study farms from across the North Island, New Zealand. From this, we propose an index system to evaluate the vulnerability of farm water supply systems. The key contributors to the vulnerability index include: water source, storage capacity, reliance on electricity, independence/interconnectedness of system elements, volume of water use and other load factors. These allow identification of key strategies for mitigating water supply vulnerability during prevention, preparation, response and recovery phases of a volcanic eruption.     

Texture development and elastic stresses in magnesiowűstite at high pressure

Cubic magnesiowűstite has been deformed in a diamond anvil cell at room temperature. We present results for (Mg_0.4Fe_0.6)O, (Mg_0.25Fe_0.75)O, and (Mg_0.1Fe_0.9)O up to 37, 16, and 18 GPa, respectively. The diffraction images, obtained with the radial diffraction technique, are analyzed using both single peak intensities and a Rietveld method. For all samples, we observe a [100] fiber texture but the texture strength decreases with increasing iron content. This texture pattern is consistent with {110}〈1-10〉 slip. The images were also analyzed for stress, elastic strains, and elastic anisotropy. In general, the stress measured in magnesiowűstite samples is lower than previously measured on MgO. The elastic anisotropy deduced from the X-ray measurements shows a broad agreement with models based on measurements with other techniques.     

Proposed method for groundwater vulnerability mapping in carbonate (karstic) aquifers: the COP method

The ‘COP method’ has been developed for the assessment of intrinsic vulnerability of carbonate aquifers in the frame of the European COST Action 620. This method uses the properties of overlying layers above the water table (O factor), the concentration of flow (C factor) and precipitation (P factor) over the aquifer, as the parameters to assess the intrinsic vulnerability of groundwater. This method considers karst characteristics, such as the presence of swallow holes (C factor) and their catchment areas as well as karstic landforms, as factors which decrease the natural protection provided by overlying layers (O factor). The P factor allows for consideration of the spatial and temporal variability of precipitation, which is considered the transport agent of contamination. Two carbonate aquifers in the South of Spain, Sierra de Líbar (a conduit flow system) and Torremolinos (a diffuse flow system), have been selected for the application and validation of the method and the results have been compared with three methods widely applied in different aquifers around the world (AVI, GOD and DRASTIC). Comparisons with these methods and validation tools (hydrogeological data and tracer test) show the advantages of the COP method in the assessment of vulnerability of karstic groundwaters.     

Spatial variability of soil quality in the surroundings of a saline lake environment

The spatial variability of the quality of the soil on the shores of a lagoon affected by hydromorphy and/or salinity can be identified (Laguna de Villacañas, Castilla La Mancha) by the use of multitemporal Landsat images in order to analyse these changes. For this purpose, TM and ETM images along with field observations and certain edaphic laboratory parameters are used. In order to identify saline-hydromorphic soils, the spatial variability of chemical and physical properties of a transect, which includes from Solonchaks to Regosols and Cambisols, have been correlated with the Normalised Difference Vegetation Index (NDVI). This index, chosen for specific dates, has proven to be very useful in detecting halophytic vegetation and relating it to the variability of the quality of these soils.     

Sampling-based flood risk analysis for fluvial dike systems

A dike system of moderate size has a large number of potential system states, and the loading imposed on the system is inherently random. If the system should fail, in one of its many potential failure modes, the topography of UK floodplains is usually such that hydrodynamic modelling of flood inundation is required to generate realistic estimates of flood depth and hence damage. To do so for all possible failure states may require 1,000s of computationally expensive inundation simulations. A risk-based sampling technique is proposed in order to reduce the computational resources required to estimate flood risk. The approach is novel in that the loading and dike system states (obtained using a simplified reliability analysis) are sampled according to the contribution that a given region of the space of basic variables makes to risk. The methodology is demonstrated in a strategic flood risk assessment for the city of Burton-upon-Trent in the UK. 5,000 inundation model simulations were run although it was shown that the flood risk estimate converged adequately after approximately half this number. The case study demonstrates that, amongst other factors, risk is a complex function of loadings, dike resistance, floodplain topography and the spatial distribution of floodplain assets. The application of this approach allows flood risk managers to obtain an improved understanding of the flooding system, its vulnerabilities and the most efficient means of allocating resource to improve performance. It may also be used to test how the system may respond to future external perturbations.     

Properties of New Coordinates for the General Three-Body Problem

This is an analysis of the features of the new coordinate system given by the principal axes of inertia, as determined by Euler angles, and twodistances related to the inertia principal moments and an auxiliar angleas coordinates, for studying the general three-body problem, interactingthrough gravitational forces.The reduction of order is performed in these new coordinates by using the angular velocity vector or the Euler angles.The Eulerian case of collinear motion is revisited from our own perspective.The value of the auxiliar angle is computed for the Sun–Earth–Moon system.     

New global positioning system reference station in Brazil

Co-located very long baseline interferometry (VLBI) and global positioning system (GPS) reference stations were installed near Fortaleza, Brazil, in 1993. Both have been important in the realization and maintenance of the International Terrestrial Reference Frame. A new-generation GPS system was installed in 2005 to replace the original station. Experience gained in the prior 12 years was used to improve the design of the GPS antenna mount. Preliminary indications are greatly improved data quality from the new station. Simultaneous observations from the nearly half-year of overlapping operation have been used to determine the local tie between the new and old GPS reference points to about 1 mm accuracy. This can be used to update the 1993 survey tie between the original GPS and the VLBI points, although there are questions about the accuracy of that measurement based on a comparison with space geodetic data. A test of removing the conical radome over the old GPS antenna indicates that it has biased the station height by about 16 mm downward, which probably accounts for most of the previous survey discrepancy.     

美国国家级干旱监测业务产品介绍

美国需要改进干旱监测与评估方法。干旱是代价昂贵的自然灾害(联邦应急管理局(FEMA),1995;W ilhite,2000),但经常被评估和预报产品的开发者忽略。相比于其他灾害,干旱表现得更模糊并且不适合用传统的评估或预报方法,它相对缓慢的发生以及其影响的复杂性,需要有一套新的方法来对它进行评估。干旱监测和预报技术的提高会使我们为应对干旱灾害做更好的准备工作,进行更好的应对实践,从而减少社会对干旱及其影响的脆弱性。为追踪和展示全美国干旱的程度、空间范围以及其影响,开发了新的干旱监测工具,研发了每周发布的国家级干旱监测业务产品(th…