Automated calibration applied to watershed‐scale flow simulations

Complexity in simulating the hydrological response in large watersheds over long times has prompted a significant need for procedures for automatic calibration. Such a procedure is implemented in the basin‐scale hydrological model (BSHM), a physically based distributed parameter watershed model. BSHM simulates the most important basin‐scale hydrological processes, such as overland flow, groundwater flow and stream–aquifer interaction in watersheds. Here, the emphasis is on estimating the groundwater parameters with water levels in wells and groundwater baseflows selected as the calibration targets. The best set of parameters is selected from within plausible ranges of parameters by adjusting the values of hydraulic conductivity, storativity, groundwater recharge and stream bed permeability. The baseflow is determined from stream flow hydrographs by using an empirical scheme validated using a chemical approach to hydrograph separation. Field studies determined that the specific conductance for components of the composite hydrograph were sufficiently unique to make the chemical approach feasible. The method was applied to the Big Darby Creek Watershed, Ohio. The parameter set selected for the groundwater system provides a good fit with the estimated baseflow and observed water well data. Copyright © 1999 John Wiley & Sons, Ltd.     

Application of discriminant analysis to evaluate compositional controls of stratiform massive sulfide deposits in Canada

Multiple discriminant analysis is used to identify systematic variations of Cu, Pb, Zn, Ag, and Au grade values in the Canadian massive sulfide deposits with the three geological parameters of age, environment, and composition of volcanic lithology. The deposits have been separated into three groups on each of the three parameter scales and discriminant functions that separated the three groups on the basis of metal grades were then obtained. The results of the analysis indicated that Pb and Cu are the most significant in indicating specific trends along the three geological parameter scales. Pb grade increases in younger deposits with an increase in the sedimentary character of their environments, or with a more felsic nature to their volcanic rocks. On the other hand, Cu grade increases in deposits that occur in volcanic environments and with a more mafic nature to the volcanic host rocks. The results could have useful applications in mineral exploration.     

Effects of climate change and urban development on the distribution and conservation of vegetation in a Mediterranean type ecosystem

Climate and land-use changes are projected to threaten biodiversity over this century. However, few studies have considered the spatial and temporal overlap of these threats to evaluate how ongoing land-use change could affect species ranges projected to shift outside conservation areas. We evaluated climate change and urban development effects on vegetation distribution in the Southwest ecoregion, California Floristic Province, USA. We also evaluated how well a conservation network protects suitable habitat for rare plant species under these change projections and identified primary sources of uncertainty. We used consensus-based maps from three species distribution models (SDMs) to project current and future suitable habitat for 19 species representing different functional types (defined by fire-response – obligate seeders, resprouting shrubs – and life forms – herbs, subshrubs), and range sizes (large/common, small/rare). We used one spatially explicit urban growth projection; two climate models, emission scenarios, and probability thresholds applied to SDMs; and high-resolution (90 m) environmental data. We projected that suitable habitat could disappear for 4 species and decrease for 15 by 2080. Averaged centroids of suitable habitat (all species) were projected to shift tens (up to hundreds) of kilometers. Herbs showed a small-projected response to climate change, while obligate seeders could suffer the greatest losses. Several rare species could lose suitable habitat inside conservation areas while increasing area outside. We concluded that (i) climate change is more important than urban development for vegetation habitat loss in this ecoregion through 2080 due to diminishing amounts of undeveloped private land in this region; (ii) the existing conservation plan, while extensive, may be inadequate to protect plant diversity under projected patterns of climate change and urban development, (iii) regional assessments of the dynamics of the drivers of biodiversity change based on high-resolution environmental data and consensus predictive mapping, such as this study, are necessary to identify the species expected to be the most vulnerable and to meaningfully inform regional-scale conservation.     

Measuring What? “Success” and “Failure” in Ghana's Oil Industry

This article analyzes the dominant ways in which questions of oil prospecting, exploration, and production are framed and outcomes measured. Using the case of Ghana, a critical institutional approach, and drawing on multiple sources of data, it shows how existing policy overlooks the structural complexities of distribution, empowerment, and corruption. Willing local institutions can make a difference, but they too have structural impediments to overcome. Thus, for now, grand statements about “success” or “failure” in the management and use of oil economies need to be taken with caution.     

FIRST RESULTS FROM VIRGO,THE EXPERIMENT FOR HELIOSEISMOLOGY AND SOLAR IRRADIANCE MONITORING ON SOHO

First results from the VIRGO experiment (Variability of solar IRradiance and Gravity Oscillations) on the ESA/NASA Mission SOHO (Solar and Heliospheric Observatory) are reported. The observations started mid-January 1996 for the radiometers and sunphotometers and near the end of March for the luminosity oscillation imager. The performance of all the instruments is very good, and the time series of the first 4–6 months are evaluated in terms of solar irradiance variability, solar background noise characteristics and p-mode oscillations. The solar irradiance is modulated by the passage of active regions across the disk, but not all of the modulation is straightforwardly explained in terms of sunspot flux blocking and facular enhancement. Helioseismic inversions of the observed p-mode frequencies are more-or-less in agreement with the latest standard solar models. The comparison of VIRGO results with earlier ones shows evidence that magnetic activity plays a significant role in the dynamics of the oscillations beyond its modulation of the resonant frequencies. Moreover, by comparing the amplitudes of different components ofp -mode multiplets, each of which are influenced differently by spatial inhomogeneity, we have found that activity enhances excitation.     

Testing of Sydney dimension sandstone for use in the conservation of heritage buildings

This paper deals with the scientific assessment of the physical properties of sandstone used in the conservation of Sydney's historic heritage sandstone buildings. The local Hawkesbury Sandstone has been widely used for all manner of constructions since the early days of the first settlement. In the nineteenth century, dimension sandstone quarries existed all over the Sydney region, and the demand for the stone was great. During this time, a true ‘freestone’ known as ‘yellow block’ sandstone, in which bedding planes were absent, was quarried extensively. This sandstone is also known as a ‘self-colouring’ sandstone, where the rock, although grey when quarried, turns a yellow–brown after a few months exposure to the atmosphere. It can be easily carved and was eminently suitable for the ornate Victorian architecture of the time. There are very few quarries within the Sydney region today capable of producing ‘yellow block’ sandstone. Whenever possible, sandstone from suitable building excavations, particularly on the Pyrmont Peninsula, is used for this work. Conservation work is extremely expensive and the building elements that most need replacement, the overhanging and decorative elements, are usually those that cost the most. It is essential that the most durable replacement stone be selected. Thus, a strict regime of scientific testing is used for any major conservation project, in order to determine the physical properties of possible replacement stone. This is the province of the geologist and involves visual observation in the quarry or excavation, which is a simple, cost-effective means of weeding out poor quality stones, followed by laboratory engineering tests to establish the physical parameters of a sandstone and finally, petrographic analysis. The results of such tests, combined with careful sampling, ensure the best possible quality of replacement material.     

Sulfur chemistry in the middle atmosphere of Venus

Venus Express measurements of the vertical profiles of SO and SO₂ in the middle atmosphere of Venus provide an opportunity to revisit the sulfur chemistry above the middle cloud tops (～58 km). A one dimensional photochemistry-diffusion model is used to simulate the behavior of the whole chemical system including oxygen-, hydrogen-, chlorine-, sulfur-, and nitrogen-bearing species. A sulfur source is required to explain the SO₂ inversion layer above 80 km. The evaporation of the aerosols composed of sulfuric acid (model A) or polysulfur (model B) above 90 km could provide the sulfur source. Measurements of SO₃ and SO (a¹Δ → X³Σ^-) emission at 1.7 μm may be the key to distinguish between the two models.     

Mapping deer habitat suitability using remote sensing and geographic information systems

This paper describes an effort to map the habitat for the Eastern Tehama Deer Herd located in Northern California. The range of this herd encompasses almost 600,000 hectares (1.5 million acres). Knowledge of the spatial distribution of suitable habitat is prerequisite to managing the deer herd. Remote sensing and GIS are appropriate tools for such an assessment. Remotely sensed data were used to map vegetation/land cover. These data along with elevation, aspect, slope, juxtaposition, and various buffer zones were input into a GIS and a model was used to produce a map of habitat suitability. The accuracy of the vegetation/land cover map was assessed and methods for validating the habitat suitability map are presented.     

(Re-)negotiating access: The politics of researching skills and knowledge for ‘sustainable communities’

The last decade has witnessed a surge of interest in ‘sustainable communities’ within the UK. This has stimulated a plethora of research aimed at acquiring a better understanding of what ‘sustainable communities’ might look like and how they can be achieved. However, this has not been accompanied by a reflection and interrogation of the actual processes, challenges and politics of doing ‘sustainable communities’ research. This paper addresses this gap by highlighting the importance of paying attention to the on-going process of negotiating access when carrying out sustainability research at the community level. We draw on a recent study of skills and knowledge for ‘sustainable communities’ in Stroud Gloucestershire, UK, to illustrate the importance of sensitivity to social relationships throughout and beyond the research trajectory within sustainability research. Our experience raises important questions about the politics of research practices when doing sustainability research ‘with’ communities and the challenges associated with participatory approaches as a means to demonstrate research impact. We argue that in developing a fuller understanding of why and how different types of community level initiatives can contribute to the ‘sustainable communities’ agenda, greater consideration needs to be given to how these community practices can be better supported through the process of doing academic research.