Lichenometric dating of Little Ice Age glacier activity in the central British Columbia Coast Mountains,Canada     

Jill E. Harvey  Dan J. Smith 《Geografiska Annaler: Series A, Physical Geography》2013,95(1):1-14

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Geographical object–oriented databases—a case study     

Peter Milne  Scott Milton  John L. Smith 《International journal of geographical information science》2013,27(1):39-55

ABSTRACT

An Australian standard for Spatial Data Transfer modelled on the draft American standard is likely to be introduced in 1993. The spatial data model is not accommodated by existing DBMS such as relational systems. Using this model as an example, the suitability of object–oriented database systems for geographical databases is demonstrated. Some initial performance figures obtained with the ONTOS system on an example database are given.  相似文献   

Family or Enterprise? What shapes the business structures of Australian farming?     

Sally Weller  Erin F. Smith  Bill Pritchard 《The Australian geographer》2013,44(2):129-142

Australian farmers navigate their contemporary circumstances through the use of different business and legal arrangements that are shaped by the commercial realities of farming and the aspirations of farm-owning households. In posing the question ‘Family or Enterprise?’, this paper examines the extent to which various household and farm business indicators are associated with different forms of farm ownership, namely sole proprietorships, partnerships, trusts and companies. Results from a postal survey of farm enterprises in Victoria, Australia suggest that both household and enterprise factors contribute to the business structure used, although the strongest determinants appear to be those factors that are less well understood in the rural geographical and sociological literature: household composition, farmer age and farm size. Greater scrutiny of the business instruments deployed by farmers to manage family and enterprise pressures should inform expectations of the fate of family farming in advanced financialised economies.  相似文献   

Climatic Change and Desert Vegetation Distribution: Assessing Thirty Years of Change in Southern Nevada's Mojave Desert     

Ross J. Guida  Scott R. Abella  William J. Smith Jr.  Haroon Stephen  Chris L. Roberts 《The Professional geographer》2013,65(2):311-322

A major theme in physical geography and biogeography is understanding how vegetation changes across geographic gradients during climate change. We assess shifts in distributions of fifteen Mojave Desert plant species based on a 2008 resurvey of 103 vegetation transects that were established in 1979. We model changes in species distributions using Maximum Entropy (Maxent) with environmental and climate variables to predict probability of species’ occurrences. Climate during the ten-year period preceding the 2008 vegetation survey was 1.5°C warmer and 3 cm per year of precipitation drier than the ten years preceding 1979. Species inhabiting the highest elevations and strongly correlated with precipitation displayed areal reductions from 1979 through 2008.  相似文献   

Meeting the needs for geographers     

Guy‐Harold Smith 《The Professional geographer》2013,65(1):5-9

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Cool,wet conditions late in the Younger Dryas in semi-arid New Mexico     

Stephen A. Hall  William L. Penner  Manuel R. Palacios-Fest  Artie L. Metcalf  Susan J. Smith 《Quaternary Research》2012,77(1):87-95

A thick alluvial sequence in central New Mexico contains the Scholle wet meadow deposit that traces upstream to a paleospring. The wet meadow sediments contain an abundant fauna of twenty-one species of freshwater and terrestrial mollusks and ten species of ostracodes. The mollusks and ostracodes are indicative of a local high alluvial water table with spring-supported perennial flow but without standing water. Pollen analysis documents shrub grassland vegetation with sedges, willow, and alder in a riparian community. Stable carbon isotopes from the wet meadow sediments have δ¹³C values ranging from ? 22.8 to ? 23.3‰, indicating that 80% of the organic carbon in the sediment is derived from C₃ species. The wet meadow deposit is AMS dated 10,400 to 9700 ¹⁴C yr BP, corresponding to 12,300 to 11,100 cal yr BP and overlapping in time with the Younger Dryas event (YD). The wet meadow became active about 500 yr after the beginning of the YD and persisted 400 yr after the YD ended. The Scholle wet meadow is the only record of perennial flow and high water table conditions in the Abo Arroyo drainage basin during the past 13 ka.  相似文献   

Geology of coal bearing Palaeogene sediments,onshore Torquay Basin,Victoria     

G. R. Holdgate  T. A. G. Smith  S. J. Gallagher  M. W. Wallace 《Australian Journal of Earth Sciences》2013,60(5):657-679

New mapping at Anglesea coal mine, and coal resource and deep groundwater drilling have provided new perspectives on the economically important Eastern View Group coal bearing sedimentary succession in the onshore Torquay Basin. In the Anglesea Syncline, the upper 35 m thick brown coal seam of the Eastern View Group is overlain by a low angle unconformity. Units overlying the coal seams include high energy, cross cutting sand channels of the Boonah Formation and lower energy channel and interchannel systems of the overlying Salt Creek and Anglesea Formations. The mine section can be correlated from borehole data with the Eastern View Group and Demons Bluff Group exposed in coastal cliff sections along the adjacent Anglesea to Torquay coast. Recently drilled coal and groundwater exploration bores provide new data on the extent of the coal measures in the Anglesea area, and details of the underlying Tertiary succession that include typical Otway Basin units such as the Pember Mudstone and Pebble Point Formations. The stratigraphy below the coal measures suggests that the Otway Ranges were not present during Palaeogene times. The rank of the brown coals on and around the Otway Ranges is higher than any other Tertiary coals in onshore Victoria, and they preserve similar patterns of rank distribution to the high rank black coals in the underlying Lower Cretaceous Otway Group. Evidence for large overburden thicknesses is lacking, and the high ranks may have been augmented by higher than normal geothermal gradients in the Early Tertiary. Comparisons between the observed depositional cycles, sequence stratigraphic cycles, and worldwide coastal onlap curves suggest that the observed disconformity boundaries are sequence boundaries that provide a chronostratigraphic framework. Sequences present may include TB4.1–4.5 in the overburden units, and TB 2.4–3.6 in the coal bearing interval.  相似文献   

Stratigraphy and tectonics of the Early to Middle Proterozoic transition,Katherine‐El Sherana area,Northern Territory     

R. S. Needham  P. G. Stuart‐Smith 《Australian Journal of Earth Sciences》2013,60(2):219-230

Abstract

Two unconformity‐bound groups of volcanic rocks and associated sediments (El Sherana and Edith River Groups) separate the older Pine Creek Geosyncline metasediments from platform cover of the McArthur Basin. Dominated by intersecting NW and ENE rift systems, the volcanics are genetically related to an extensional tectonic system which was also active during deposition of the Pine Creek Geosyncline sequence. In contrast, the younger platform cover was deposited in a relatively stable environment. The rift valleys were filled with rhyolite flows, ignimbrite and ill‐sorted arenite and rudite, and flyschoid sediments spread onto adjacent lands. Following tight upright folding, granite intrusion and erosion, an extensive ignimbrite sheet (=6000 km²) spread from a centre probably at the intercept of the two rifts. Microgranite at this intersection was possibly emplaced in the evacuated magma chamber. The volcanic sequences were deeply eroded and weathered before platform cover deposition began. The platform sediments, represented in the area by the Kombolgie Formation, were deposited from about 1690 Ma to 1650 Ma, and their base is taken as the closest stratigraphic indicator of the boundary between the Early and Middle Proterozoic.  相似文献   

Implementation/optimization of moving least squares response surfaces for approximation of hurricane/storm surge and wave responses     

Alexandros A. Taflanidis  Gaofeng Jia  Andrew B. Kennedy  Jane M. Smith 《Natural Hazards》2013,66(2):955-983

One of the important recent advances in the field of hurricane/storm modelling has been the development of high-fidelity numerical simulation models for reliable and accurate prediction of wave and surge responses. The computational cost associated with these models has simultaneously created an incentive for researchers to investigate surrogate modelling (i.e. metamodeling) and interpolation/regression methodologies to efficiently approximate hurricane/storm responses exploiting existing databases of high-fidelity simulations. Moving least squares (MLS) response surfaces were recently proposed as such an approximation methodology, providing the ability to efficiently describe different responses of interest (such as surge and wave heights) in a large coastal region that may involve thousands of points for which the hurricane impact needs to be estimated. This paper discusses further implementation details and focuses on optimization characteristics of this surrogate modelling approach. The approximation of different response characteristics is considered, and special attention is given to predicting the storm surge for inland locations, for which the possibility of the location remaining dry needs to be additionally addressed. The optimal selection of the basis functions for the response surface and of the parameters of the MLS character of the approximation is discussed in detail, and the impact of the number of high-fidelity simulations informing the surrogate model is also investigated. Different normalizations of the response as well as choices for the objective function for the optimization problem are considered, and their impact on the accuracy of the resultant (under these choices) surrogate model is examined. Details for implementation of the methodology for efficient coastal risk assessment are reviewed, and the influence in the analysis of the model prediction error introduced through the surrogate modelling is discussed. A case study is provided, utilizing a recently developed database of high-fidelity simulations for the Hawaiian Islands.  相似文献   

Comparative Evaluation of Single‐Well LNAPL Tracer Testing at Five Sites          下载免费PDF全文

Andrew Pennington  Jonathon Smith  Brad Koons  Craig E. Divine 《Ground Water Monitoring & Remediation》2016,36(2):45-58

Light nonaqueous phase liquid (LNAPL) tracer testing is a technique used to directly measure LNAPL flow in situ and evaluate LNAPL mobility and recoverability. The test method consists of adding a fluorescent oil‐soluble tracer to LNAPL within a well, isolating small volumes of LNAPL with known tracer concentrations for use as in‐well calibration standards, and measuring the rate of tracer concentration decline in the well over time. The test measures LNAPL flux through the well, which is directly related to LNAPL mobility and recoverability in the surrounding formation. Test results for a total of 29 wells at five sites are presented. Results from LNAPL tracer testing were comparable to results obtained through other methods, and the method offers a time‐averaged result measured over a relatively long period, in ambient conditions, and reflects the influences of heterogeneity and hydraulic changes. In some cases, tracer concentration decline followed unexpected patterns, and these data have led to a better understanding of test assumptions, mechanisms influencing tracer distribution, and options to improve test execution and data interpretation. Method improvements developed over the course of the field studies included refinement of pre‐test screening of LNAPL fluorescence and improvements to measurement equipment. Overall, the field studies confirmed the technical validity and usefulness of the LNAPL tracing technique to support LNAPL mobility and recoverability assessments.  相似文献