GIS in local government: some findings from Great Britain

Abstract

Local government is one of the most important groups of users of geographical information systems (GIS). The significant interest amongst users and the varied demands to be made of GIS have stimulated discussion in many countries. This article presents some of the findings of a research project which is currently exploring the impact of GIS on British local government. The discussion examines the results of a comprehensive survey of all 514 local authorities in Great Britain. These findings provide an overview of GIS adoption in relation to type of local authority and geographical location. Particular attention is focused on the type of systems which have been adopted, the take-up of GIS over time, the software and hardware being utilized and the perceived benefits and problems associated with GIS. The results demonstrate that take-up has been most pronounced in the larger authorities, particularly in the southern part of Great Britain, with the most popular combination of equipment being Arc/Info software and workstations. For those authorities presently implementing a GIS, the technology is expected to improve existing capabilities for information processing rather than enhance decision-making or help achieve savings. In seeking these benefits authorities are encountering considerable problems which include basic technical difficulties in getting the equipment to work, data-related issues surrounding the collection, standardization and maintenance of geographical information, and profound organizational considerations associated with the introduction of information technology into complex environments. There is an urgent need for in-depth case studies which evaluate the experiences of users in relation to the vital process of implementation.     

A comparison of two methods to create tracks of moving objects: linear weighted distance and constrained random walk

As an object moves through space, it creates a track (or path) representing the object's past and present position and associated attributes. If data capture fails, then positions along the tracks are unknown. The particular problem we address in this paper is to create tracks of moving objects with missing data. We implement and test two techniques that create continuous tracks of two primate species (Ateles geoffroyi, the red spider monkey, and Cebus capucinus, the white-faced capuchin). Continuous tracks were needed to calculate home range and to analyze daily ranging patterns for each species. Establishing continuous tracks of primates through field data alone, however, was impossible due to challenging field conditions. The results of the analysis using tracks with interpolated positions helped establish that Ateles tend to move directly to their destination while Cebus tended to follow a more wandering track.     

Geochemical,mineralogical and microbiological characteristics of sediment from a naturally reduced zone in a uranium-contaminated aquifer

Localized zones or lenses of naturally reduced sediments have the potential to play a significant role in the fate and transport of redox-sensitive metals and metalloids in aquifers. To assess the mineralogy, microbiology and redox processes that occur in these zones, several cores from a region of naturally occurring reducing conditions in a U-contaminated aquifer (Rifle, CO) were examined. Sediment samples from a transect of cores ranging from oxic/suboxic Rifle aquifer sediment to naturally reduced sediment were analyzed for U and Fe content, oxidation state, and mineralogy; reduced S phases; and solid-phase organic C content using a suite of analytical and spectroscopic techniques on bulk sediment and size fractions. Solid-phase U concentrations were higher in the naturally reduced zone, with a high proportion of the U present as U(IV). The sediments were also elevated in reduced S phases and Fe(II), indicating it is very likely that U(VI), Fe(III), and SO₄ reduction has occurred or is occurring in the sediment. The microbial community was assessed using lipid- and DNA-based techniques, and statistical redundancy analysis was performed to determine correlations between the microbial community and the geochemistry. Increased concentrations of solid-phase organic C and biomass in the naturally reduced sediment suggests that natural bioreduction is stimulated by a zone of increased organic C concentration associated with fine-grained material and lower permeability to groundwater flow. Characterization of the naturally bioreduced sediment provides an understanding of the natural processes that occur in the sediment under reducing conditions and how they may impact natural attenuation of radionuclides and other redox sensitive materials. Results also suggest the importance of recalcitrant organic C for maintaining reducing conditions and U immobilization.     

Reconstructing past glacier dynamics and erosion from glacial geomorphic evidence: Snowdon,North Wales

Bedrock surfaces exposed around Llyn Llydaw, North Wales demonstrate contrasting styles of erosion beneath a Late Devensian ice sheet and a Loch Lomond Stadial (LLS) valley glacier. Ice sheet erosion involved lee-side fracturing, surface fracture wear and abrasive wear, while LLS erosion was primarily by abrasive wear. Preservation of ice sheet erosional features indicates limited rates of erosion during the LLS. Analysis of the geometry and distribution of erosional markings suggests that the low erosional capacity of the LLS glacier was due to a low basal sliding velocity. This prevented the formation of lee-side cavities, reduced the debris flux over the bed and minimised particle-bed contact loads. Reconstructions of the mass balance and geometry of the LLS glacier indicate that most of its balance velocity could be achieved by internal deformation alone. A combination of low subglacial water pressures and an unusually rough substrate explain the low sliding velocities. High bed roughness is due to the absence of leeside cavities and a change in flow orientation between ice sheet and LLS times, which meant that the LLS glacier was in contact with roughness elements which were generated in cavities beneath the ice sheet.     

70-cm radar observations of 433 Eros

Radar observations of 433 Eros were made at the Arecibo Observatory using a wavelength of 70 cm during the close approach of Eros to Earth in mid-January, 1975. A peak radar cross section of 39 ± 15 km² was observed. The spectral broadening obtained was approximately 30 Hz, which is consistent with a value of 16 km for the maximum radius of the asteroid. The surface of Eros appears to be relatively rough at the scale of a wavelength as compared to the surfaces of the terrestrial planets and the Moon. The composition of the surface is not well determined, except that it cannot be a highly conducting metal. A single measurement each of round-trip echo times delay and doppler shift was made.     

Microbial distribution and abundance in response to physical and biological processes on the continental shelf of southeastern U.S.A.

The distribution and abundance of bacteria and phytoplankton on the continental shelf of the southeastern United States were observed in relation to physical processes. Phytoplankton production was influenced by inputs of water of reduced salinity from the estuaries and by inputs of high salinity, low-temperature water from the west front of the Gulf Stream. The distribution of chlorophyll suggests that in each case production is influenced both by inputs of nutrients and by the enhanced vertical stability associated with the stratification of waters of different densities. The standing stock of bacteria on the inner shelf, 10⁶ ml^?1, is little changed by the influx of water of reduced salinity. On the outer shelf, where the usual standing stock of bacteria is 10⁵ ml^?1, the numbers increase to 10⁶ ml^?1 in and above intrusions of Gulf Stream water in which phytoplankton blooms have developed, suggesting that the bacteria respond to products of both phytoplankton and zooplankton production. Adenylate energy charge values in the waters of the southeastern shelf are variable and volatile. At times values of 0.7 to 0.8 are widespread over most of the shelf, while at other times values <0.6 are common, with localized patches of high values. Both autotroph-dominated and heterotroph-dominated microbial communities show these variations.     

ELA-ICP-MS U–Pb zircon geochronology of regional volcanism hosting the Bajo de la Alumbrera Cu–Au deposit: implications for porphyry-related mineralization

ELA-ICP-MS U–Pb zircon geochronology has been used to show that the porphyritic intrusions related to the formation of the Bajo de la Alumbrera porphyry Cu–Au deposit, NW Argentina, are cogenetic with stratigraphically well-constrained volcanic and volcaniclastic rocks of the Late Miocene Farallón Negro Volcanic Complex. Zircon geochronology for intrusions in this deposit and the host volcanic sequence show that multiple mineralized porphyries were emplaced in a volcanic complex that developed over 1.5 million years. Volcanism occurred in a multi-vent volcanic complex in a siliciclastic intermontane basin. The complex evolved from early mafic-intermediate effusive phases to a later silicic explosive phase associated with mafic intrusions. Zircons from the basal mafic-intermediate lavas have ages that range from 8.46±0.14 to 7.94±0.27 Ma. Regionally extensive silicic explosive volcanism occurred at ~8.0 Ma (8.05±0.13 and 7.96±0.11 Ma), which is co-temporal with intrusion of the earliest mineralized porphyries at Bajo de la Alumbrera (8.02±0.14 and 7.98±0.14 Ma). Regional uplift and erosion followed during which the magmatic-hydrothermal system was probably unroofed. Shortly thereafter, dacitic lava domes were extruded (7.95±0.17 Ma) and rhyolitic diatremes (7.79±0.13 Ma) deposited thick tuff blankets across the region. Emplacement of large intermediate composition stocks occurred at 7.37±0.22 Ma, shortly before renewed magmatism occurred at Bajo de la Alumbrera (7.10±0.07 Ma). The latest porphyry intrusive event is temporally associated with new ore-bearing magmatic-hydrothermal fluids. Other dacitic intrusions are associated with subeconomic deposits that formed synchronously with the mineralized porphyries at Bajo de la Alumbrera. However, their emplacement continued (from 7.10± 0.06 to 6.93±0.07 Ma) after the final intrusion at Bajo de al Alumbrera. Regional volcanism had ceased by 6.8 Ma (6.92±0.07 Ma). The brief history of the volcanic complex hosting the Bajo de la Alumbrera Cu–Au deposit differs from that of other Andean provinces hosting porphyry deposits. For example, at the El Salvador porphyry copper district in Chile, magmatism related to Cu mineralization was episodic in regional igneous activity that occurred over tens of millions of years. Bajo de la Alumbrera resulted from the superposition of multiple porphyry-related hydrothermal systems, temporally separated by a million years. It appears that the metal budget in porphyry ore deposits is not simply a function of their longevity and/or the superposition of multiple porphyry systems. Nor is it a function of the duration of the associated cycle of magmatism. Instead, the timing of processes operating in the parental magma body is the controlling factor in the formation of a fertile porphyry-related ore system.Electronic Supplementary Material Electronic supplementary material to this paper can be obtained by using the Springer Link server located at Editorial handling: N. White     

Production of vibrationally excited N2 by electron impact

Energy transfer from electrons to neutral gases and ions is one of the dominant electron cooling processes in the ionosphere, and the role of vibrationally excited N₂ in this is particularly significant. We report here the results from a new calculation of electron energy transfer rates (Q) for vibrational excitation of N₂, as a function of the electron temperature T_e. The present study was motivated by the development of a new cross-section compilation for vibrational excitation processes in N₂ which supercedes those used in the earlier calculations of the electron energy transfer rates. We show that the energy dependence and magnitude of these cross sections, particularly in the region of the well-known resonance in N₂, significantly affect the calculated values of Q. A detailed comparison between the current and previous calculated electron energy transfer rates is made and coefficients are provided so that these rates for transitions from level 0 to levels 1-10 can be calculated for electron temperatures less than .