Browsing by Subject "Geographic Information Systems"

Now showing 1 - 4 of 4
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    Open Access
    Cartographic GIS standards adopted by the Department of Water Affairs and Forestry : a case study
    (1996) De Klerk, Jeanne Louise; Martin, C G C
    The Department of Water Affairs and Forestry (DWAF) acquired a Geographic Information System (GIS) in 1987. The purpose of acquiring such a system was to aid the department in implementing their water resource management strategy of that time. On acquiring this system it was well recognised that the GIS would need to communicate geo-referenced information, generated by analysis and modelling to decision makers by means of graphic representations or maps (Olivier et al., 1990: 14 73). Towards the end of 1990 it became apparent that the department needed to standardise cartographic output of this system. Maps on the same theme, which were produced at different sites were not comparable and graphic communication was not effective. A consultant was appointed, who, in conjunction with the departmental digital cartographer, established criteria and standards which were flexible enough to accommodate mapping on a wide variety of themes. These standards were implemented, to a limited extent in July 1994. Standards were set for map encoding, map content and map composition. This report investigates how effective these standards have been. The effectiveness of these standards have been measured in terms of the five recognised cartographic design principles that have been identified by Robinson et al. (1984), Wood (1992) and Dent (1990). These include the clarity and legibility of maps, the distinction between figure and ground, the hierarchical organisation of mapped information, the visual contrast of marks on maps and the visual balance or layout of the finished map. A sample of maps made after the implementation of cartographic standards at the department was compared to a sample of comparable maps made prior to the implementation of these standards. In a large organisation like the department the success of such standards do not depend on the standards alone but also on their implementation. Implementation related problems were identified by comparing standardised maps with the standards. The outcome of the investigation proved that the effectiveness of graphic communication had indeed improved albeit to a varying degree. In most cases the standards were adequate and the main problems actually lay with their implementation. Recommendations on the implementation and the few aspects of the standards that require amendment have been included in this report.
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    Open Access
    The development of a Geographic information system for environmental monitoring on the Cape Peninsula, and an assessment of the use of spot imagery for vegetation mapping
    (1991) Webster, Michael S; Moll, EJ; Martin, C G C
    This thesis concerns the establishment of a Geographic Information System for the Cape Peninsula and the use of SPOT satellite imagery to map land cover classes. The former is seen as a necessary tool to promote judicious conservation management decisions for the fragile "Fynbos" ecosystem, and the latter as a convenient means of acquiring up-to-date information concerning the environment, and to monitor change.
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    Open Access
    Geographic information system (GIS) integration of geological, geochemical and geophysical data from the Aggeneys base metal province, South Africa
    (1994) Naicker, Isayvani; De Wit, Maarten
    Geographic Information System (GIS) technology aids in storage, manipulation, processing, analysis and presentation of spatial data sets. GIS can effectively interrogate large multidisciplinary exploration data sets in the search for new mineral exploitation targets. A spatial database, the AGGeneys Exploration Database (AGGED), has been created, comprising exploration data gathered during two decades of exploration for base-metals in the Aggeneys area, Bushmanland, South Africa. AGGED includes data extracted from analog maps, as well as digital remotely sensed sources, stored in vector and raster data structures, respectively. Vector data includes field based observations such as the extent of outcropping geological units, litho- and chrono-stratigraphic data; structural data; laboratory data based on regional geochemical stream sediment and traverse sampling; cadastral data and known mineral occurrences. Raster data includes Landsat satellite TM imagery and airborne magnetic data. Spatial variation within single data maps are examined. Spatial correlation between three different data maps are facilitated using colour analysis of hue, saturation and value components in a perceptual colour model. Simultaneously combining lead and zinc data with Landsat TM and geophysical magnetic data spatially delineates four new "geoscience" anomalies in the area under investigation. Two distinctive anomalies occur on the farms Aroams and Aggeneys. The Aroams anomaly (GSAl) has not been previously recognised, whereas the Aggeneys anomaly (GSA2) has been located before. The two other "geoscience" anomalies, on the farm Haramoep (GSA3 and GSA4 ), are slightly less distinct. Overlaying fold axial trace patterns and anomalies on the farm Haramoep, indicate that F2 and F3 fold structures are closely associated with these two anomalies. The location of the Aroams anomaly occurs along the same east-west trend of the four known major ore-deposits viz. Big Syncline, Broken Hill, Black Mountain and Gamsberg. Extrapolating F2 and F3 fold patterns using magnetic data locates this Aroams anomaly along the F3 axial trace extending from Big Syncline through to Gamsberg. The elevated Pb-Zn geochemical anomaly and structural data associated with the Aroams anomaly makes it a promising future exploitation target. The AGGED database can be expanded both in geographic extent to include surrounding areas, and to allow for inclusion of future surveys. Analytical processing of data in AGGED can also be continued and expanded. GIS is a burgeoning field and developments in GIS technology will impact on the explorationist. Developments in object-oriented and knowledge-based database technologies, visualisation techniques and artificial intelligence, incorporated in future GIS need to be closely monitored and evaluated by geoscience explorationists.
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    Open Access
    Open source GIS for HIV/AIDS management
    (BioMed Central Ltd, 2008) Vanmeulebrouk, Bas; Rivett, Ulrike; Ricketts, Adam; Loudon, Melissa
    BACKGROUND: Reliable access to basic services can improve a community's resilience to HIV/AIDS. Accordingly, work is being done to upgrade the physical infrastructure in affected areas, often employing a strategy of decentralised service provision. Spatial characteristics are one of the major determinants in implementing services, even in the smaller municipal areas, and good quality spatial information is needed to inform decision making processes. However, limited funds, technical infrastructure and human resource capacity result in little or no access to spatial information for crucial infrastructure development decisions at local level.This research investigated whether it would be possible to develop a GIS for basic infrastructure planning and management at local level. Given the resource constraints of the local government context, particularly in small municipalities, it was decided that open source software should be used for the prototype system. RESULTS: The design and development of a prototype system illustrated that it is possible to develop an open source GIS system that can be used within the context of local information management. Usability tests show a high degree of usability for the system, which is important considering the heavy workload and high staff turnover that characterises local government in South Africa. Local infrastructure management stakeholders interviewed in a case study of a South African municipality see the potential for the use of GIS as a communication tool and are generally positive about the use of GIS for these purposes. They note security issues that may arise through the sharing of information, lack of skills and resource constraints as the major barriers to adoption. CONCLUSION: The case study shows that spatial information is an identified need at local level. Open source GIS software can be used to develop a system to provide local-level stakeholders with spatial information. However, the suitability of the technology is only a part of the system - there are wider information and management issues which need to be addressed before the implementation of a local-level GIS for infrastructure management can be successful.