This dissertation presents the design and implementation of a graphical user interface (GUI) to display spatial data in a web-based environment. The work is a case study for a web-based framework for distributed applications, the Web Computing Skeleton, using a distributed open spatial query mechanism to display the geographic data. The design is based on investigation of geographic information systems (GISs), GUI design and properties of spatial query mechanisms. The purpose ofthe GUI is to integrate information about a geographic area; display, manipulate and query geographic-based spatial data; execute queries about spatial relationships and analyse the attribute data to calculate the shortest routes for emergency response. The GUI is implemented as a Java applet embedded in a web document that communicates with the application server via generic GIS classes that provide a common interface to various GIS data sources used in the spatial query mechanism to access a geographic database. Features that are supported by the distributed open spatial query mechanism include a basic set of spatial selection criteria, spatial selection based on pointing, specification of a query window, description of a map scale and identification of a map legend. The design is based on a formal design process that includes the selection of a conceptual model, identification of task flow, major windows and dialog flow, the definition of fields and detailed window layout and finally the definition of field constraints and defaults. The conceptual model characterises the application and provides a framework for users to learn the system model. This model is conceptualised as a map that the user manipulates directly. Unlike a typical map, which just shows spatial data such as roads, cities, and country borders, the GIS links attribute data like population statistics to the spatial data. This link between the map data and the attribute data makes the GIS a powerful tool to manipulate and display data. To measure the performance of displaying spatial data, two main factors are considered, namely processing speed and display quality. Factors that affect the processing speed include the rate of data transfer from the generic GIS classes, the rate data is downloaded over the network and the speed of execution of the drawing. Two factors that influence the spatial data display quality are pixel distance and bitmap quality. The pixel distance set in the geographic database is represented by two pixels on the display screen, which affects the display quality since the pixel distance is the upper limit for display granularity. This means that setting the pixel distance is a trade-off between the processing speed and the display quality. Bitmaps are raster images that are made up of pixels or cells. To improve the raster image quality, the bitmap resolution can be adjusted to display more pixels per centimetre. / Dissertation (MSc (Computer Science))--University of Pretoria, 2007. / Computer Science / unrestricted

Geography education is undergoing change in K-12 education due in part to the introduction of geospatial technologies, including geographic information systems (GIS). Although active engagement in GIS mapping would seem to enhance students’ spatial thinking, little is known about the mapping strategies that students employ or about changes in their geographic knowledge that would result. This study, set in a high school Advanced Placement human geography class, sought to contribute to these areas of inquiry. Participants performed a web-based GIS task focused on global population and migration. Attention in the study was on (a) the strategies students employed when investigating geographic phenomena using GIS, (b) changes in their cognitive maps, as assessed through sketch maps, resulting from the activity, (c) the relationship between GIS maps and sketch maps, and (d) the ways in which a subset of students serving as case studies explained the nature of their mapping. The study employed screen-captures, video-recordings, observations, pre- and post-study sketch maps, and interviews. Analyses of the GIS process revealed that, in creating their maps, the students used a number of strategies, which included searching, layering, removing layers of data, adjusting transparency, editing, and noting. Although searching and layering were employed by all students, there was variability across students in use of the other strategies. With respect to changes in their spatial thinking, analyses of the sketch maps showed increases in elaboration and accuracy in terms of migration patterns. When GIS maps were compared to sketch maps, analyses showed relations for many students. The six students who served as case studies revealed major connections between personal interests and the reasoning employed in mapping. They also described their entry points into the process. The study shows how real-time data collection, including screen captures, as well as more static measures, specifically sketch maps, can provide insights into the spatial thinking of students while using GIS. It provides some support to educational approaches to geography in which students become creators of maps, not simply users of maps, and suggests that, through their own mapping process, students expand their cognitive maps and enhance their spatial thinking.

Thesis (MSc)--University of Stellenbosch, 2004 / ENGLISH ABSTRACT: The Sandveld, a potato growing area of the Western Cape is subject to significant groundwater abstraction for both municipal and agriculture purposes. The climate is arid and sensitive and important ecosystems in the area are showing varying degrees of impact. Management measures are needed to ensure ongoing sustainable development of the area. In this study, different interpolation techniques were evaluated to calculate values for unsampled variables rainfall and groundwater elevation. Local deterministic techniques as well as geostatistical techniques were used. It was found that geostatistical techniques, especially with collateral information, such as topography, provided a more accurate result. For environmental studies of this nature, Kriging is recommended as interpolation technique. The underlying data will determine the selection of the particular type of Kriging. Data was extracted from a customized relational database, geoMon, used for data capture, retrieval, processing and reporting. Ease of data extraction facilitated analysis. The interpolated grids were applied in two scenarios: Recharge calculations and quantification as well as a new classification approach according to Resource Directed Measures (RDM). Management classes were defined based on GIS-derived data. / AFRIKAANSE OPSOMMING: Die Sandveld, ‘n aartappelverbouingsgebied in die Wes-Kaap, ondergaan aansienlike grondwateronttrekking vir beide munisipale sowel as landbou doeleindes. Die klimaat is dor en droog en sensitiewe en belangrike ekosisteme in die area ondervind wisselende impakvlakke. Bestuursmaatreëls word benodig om volhoubare ontwikkeling van die area te verseker. In hierdie studie is verskillende interpolasie tegnieke om onbekende waardes vir veranderlikes gebruik in grondwater evaluasie te bereken, evalueer. Lokale deterministiese tegnieke sowel as geostatistiese tegnieke is gebruik. Geostatistiese tegnieke, veral gebruik saam met addisionele inligting soos topografie, bereken meer akkurate resultate. Vir omgewingsstudies van hierdie aard, word Kriging aanbeveel as interpolasie tegniek. Eienskappe van die onderliggende data word gebruik om die tipe Kriging aan te dui. Data is onttrek uit ‘n gebruikersaangepaste databasis, geoMon, wat gebruik is vir datavaslegging, onttrekking, prosessering en verslaggewing. Die gemak waarmee data onttrek kon word het analise vergemaklik. Geïnterpoleerde data is gebruik vir grondwateraanvullingsberekeninge en -kwantifisering sowel as ‘n nuwe benadering tot klassifikasie volgens hulpbron gerigte maatreëls. Bestuursklasse gebaseer op GIS-afgeleide data, is gedefinieer.

The working hypothesis for this study is that the introduction of GIS technology into the ancient procedures of map-making has changed the map-making context sufficiently to require a revision of the way we think about, learn from, and use maps, specifically in the public involvement process in natural resource management. The assumption that we jointly know what maps mean, and how to use them, has been carried unchallenged into the vastly changed arena of digital, information-dense, and highly technical map-making, courtesy of Geographic Information Systems (GIS). It has remained unchallenged even as the social context for environmental policy-making is undergoing historic upheaval. GIS fundamentally changes how information is viewed, literally, by many different groups, for its maps and databases contain varying levels of uncertainty, multiple embedded assumptions, potentially privileged knowledge, and considerable power as story-makers, along with unintended and unexplored social consequences. GIS maps/databases are used here as the central refractor of ideas about relationships between scientists and lay audiences; between the post-modern understanding of privilege and social change; and ultimately between technology and meaning, where changing expectations about the role of science in natural resource management resonate most profoundly. Key research questions are: (1) How can GIS maps contribute to mutual learning in the natural resource management arena?, and (2) Which consequences of GIS development could change approaches to natural resource management? The exploratory case study used to address these questions examines GIS maps from the Coastal Landscape Analysis and Modeling Study (CLAMS), a landscape-scale bioregional assessment in western Oregon that draws heavily on GIS technology to illustrate ecological and socioeconomic dynamics and interactions. Findings suggest that use of GIS through time may change the realm of designing and structuring decision problems, adjusting it from a largely science-driven exercise in natural resource management to a more collaborative story-making one. While epistemological differences between scientists and lay audiences remain, they can be offset through such collaboration, with concomitant shifts in power structures that could affect a range of conditions including rates of technology diffusion, and management of a broad transition in how natural resources are perceived and utilized. / Graduation date: 2005

This study has attempted to model and quantify the impacts of Beneficial Management Practices (BMP) like buffer strips on the phosphorus concentration and loading in the Buck Creek Watershed of Central Indiana. The GIS based modeling was done using the Soil and Water Assessment Tool (SWAT) developed by the U.S. Department of Agriculture-Agricultural Research Services (USDA-ARS). The results from the EPA funded two year (2002-2004) Upper White River Watershed Project (UWRWP) for the Buck Creek Watershed were used as the measured base data for the modeling evaluation. These measured data were compared against the data generated out of the model simulation based on two different scenarios which took into consideration the combinations of land use, agricultural management practices, point source pollutions and BMPs. Scenario-1 simulated all the aspects of land use intensity, moderate agricultural management practices and moderate point source pollutions taking place in the Buck Creek watershed. While running the model in scenario-1, there was a noticeable increase in the phosphorus loading to the sub-watersheds ranging from 10% in the lowland sub-watershed of BC-4 to 39% in the highland sub-watershed of BC-7. In scenario-2, BMPs were implemented in the model which added 100 acres of vegetated buffer strips uniformly in all sub-watersheds and 3 acres of grassed buffers along the streams except BC-3. On re-running the model in scenario-2, there was a drastic decline in the phosphorus loading to the stream. It has been noted that there was at least 15% reduction in the loading of phosphorus to the stream where buffer strips were implemented. The present GIS modeling study helped to quantify the changes in the loading of sediments and nutrients which are induced by any parametric changes in the watershed including soil, slope, land use, agricultural management practices and BMPs. / Department of Geography

Thesis (MA)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Recently there has been growing interest in evaluating the performance and outcomes of spatial planning policies worldwide. In response to this a research was carried out to evaluate and monitor the effectiveness of spatial planning policies in the Cape Metropolitan Area (CMA). The Planning Indicators Model (PIM), which consists of a set of twenty-six indicators, was applied to monitor and measure the extent to which the Metropolitan Spatial Development Framework (MSDF) has affected land use and physical development in the CMA. To achieve the aim of the study, the research was divided into three phases. The first phase involved a literature review, the second phase involved interviews with planning officials and lastly, the collection of different thematic datasets required to run the Planning Indicators Model. The data sets were used to monitor and display spatiotemporal variations in conformance and performance indices in the form of maps. These maps were used to identify areas where strengths can be protected and where weaknesses need to be corrected. From a set of 26 indicators used for this study only two indicators monitored conformances (Growth of informal housing townships) over the period 1993 – 1998; the others simply indicated the present conditions. This means that the rest of the indicators did not show trends. However, the data are presented in this report as a useful baseline for future conformance and performance monitoring exercises. The study also revealed that for the past twelve years the MSDF has been the subject of extensive debate within the local authorities. Also several indicators seem to overlap and need to be clearly defined, thus it is recommended that some of these indicators should be combined to avoid duplication and confusion. Generally, the PIM can assist in making the impact of spatial planning greater in the CMA. / AFRIKAANSE OPSOMMING: Onlangs is daar wêreldwyd groeiende belangstelling in die prestasies en uitkomstes van ruimtelike beplannings- beleide. In reaksie daarop is hierdie navorsing gedoen om die doeltreffendheid van die ruimtelike beplannings- beleide van die Kaapse Metropolitaanse Gebied (KMG) te evalueer en te monitor. Die Beplannings Aanwysers Model (BAM) wat bestaan uit ‘n stel van ses-en- twintig aanwysers, is aangewend om te meet tot hoeverre die Metropolitaanse Ruimtelike Ontwikkelings Raamwerk grondgebruik en fisiese ontwikkeling in die Kaapse Metropolitaanse Gebied beïnvloed het. Om die doelwit van hierdie studie te verwesenlik, is die navorsing gedoen in drie fases. Die eerste fase bestaan uit ‘n oorsig van die literatuur en die tweede fase uit onderhoude met amptenare verantwoordelik vir beplanning. Die laaste fase beslaan die versameling van die verskillende tematiese stelle data wat benodig word vir die Beplannings Aanwysers Model. Die stelle data is gebruik om die ruimtelike- en tydsvariasies in die konformering- en prestasie indekse te monitor en ten toon te stel in die vorm van kaarte. Hierdie kaarte is gebruik om die gebiede te identifiseer waar sterkpunte behoue moet bly en waar swakpunte reggestel moet word. Uit die stel van 26 aanwysers wat gebruik is vir hierdie studie, het net twee aanwysers konformering (Die groei van dorpsgebiede met informele behuising) gedurende die periode 1993 – 1998 gemonitor; die ander het eenvoudig die huidige toestand aangetoon. Dit beteken dat die ander aanwysers nie tendense aangetoon het nie. Die data word egter in hierdie verslag weergee as ‘n nuttige basis vir die toekomstige monitor van konformering en prestasie. Die studie toon ook aan dat daar gedurende die afgelope twaalf jaar baie deur plaaslike owerhede gedebatteer is oor die Metropolitaanse Ruimtelike Ontwikkelings Raamwerk. Ook oorvleuel sommige van die aanwysers en moet hulle meer duidelik omskryf word. Dus word daar aanbeveel dat sommige van die aanwysers gekombineer moet word om duplikasie en verwarring te voorkom. Oor die algemeen kan die Beplanning Aanwysers Model help om die impak van ruimtelike beplanning op die Kaapse Metropolitaanse Gebied te bevorder.

This study is a test of a methodology to predict changes in elevation and shoreline position of coastal wetlands in Trinity Bay, Texas, in response to projected sea level rise. The study combines numerical modeling and a geographic information system. A smoothing technique is used on a United States Geographical Survey (USGS) digital elevation model to obtain elevation profiles that more accurately represent the gently sloping wetlands surface. The numerical model estimates the expected elevation change by raster cell based on input parameters of predicted sea level rise, mineral and organic sedimentation rates, and sediment autocompaction rates. A GIS is used to display predicted elevation changes and changes in shoreline position as a result of four projected sea level rise scenarios over the next 100 years. Results demonstrate that this numerical model and methodology are promising as a technique of modeling predicted elevation change and shoreline migration in wetlands. The approach has potential utility in coastal management applications.

Land, water and natural resources are under increasing pressure due to rising demands for food and energy from the rapidly growing global population. Across a catchment there can be multiple stakeholders with conflicting opinions over how space and resources should be used and managed. Consequently, it is important to consider the suitability of a catchment for a particular purpose to optimise use of the area and minimise potential conflicts and impacts on the wider environment. Aquaculture is a significant contributor to world food supply and as fisheries are unlikely to increase it is expected that the industry will continue to grow and expand in the future to help meet food security requirements. As a result, it is essential that the sector aims for sustainable development within the most suitable locations. However, it can be difficult to assess the suitability of multiple large catchments and some issues may not be immediately apparent. This project aimed to show how spatial models could be used as decision support tools to evaluate the suitability of large catchments for sustainable aquaculture. Four large areas of importance to aquaculture were selected; covering 10,148km2, 26,225km2, 48,319km2 and 66,283km2 in Bangladesh, China, Thailand and Vietnam respectively. Asia is by far the most dominant aquaculture region in the world and each of the four study areas contribute to local, regional and global food supplies. The study area in Bangladesh was located in Khulna region in the south west of the country and the main species of focus were prawn and shrimp. The Chinese study area was located in the south eastern province of Guangdong and the main species covered were tilapia and shrimp. Similarly, in Thailand, the main species evaluated were tilapia and shrimp whilst the study area extended across the Central region. Finally, the largest study area was the Mekong Delta in Vietnam and the main species of focus in this area were pangasius catfish and shrimp. One of the challenges in modelling large catchments is model applicability and data availability. Often, the required data are not available (or accessible) and it would be difficult, time consuming and expensive to collect new information. Furthermore, when assessing multiple areas is it vital that a representative and unbiased approach is used where no one catchment is favoured over the other due to higher quality data. Therefore, this study used data that are available for almost any area in the world; allowing future application of the models and enabling effective and unbiased decision support. Four modelling stages were employed in this study to evaluate the suitability of large catchments for sustainable aquaculture development. The first stage was the classification of seasonal land use models from satellite imagery. This provides information on what the land is used for and how aquaculture could impact or be impacted by the wider environment. The second step was the development of seasonal models of site suitability using optimal values within a GIS-based multi-stage framework. These models identify which locations are best for culture and can also be used to estimate the availability of areas for food production. The next stage investigated the use of Maxent as a novel approach in site suitability modelling to evaluate the conditions experienced by existing farms. The information from Maxent can be used to identify trends, opportunities and concerns related to sustainable management and farm locations. Finally, qualitative models of non-point source pollution (NPSP) were developed which assess the risk of NPSP within a catchment. NPSP is an issue which can impact both aquaculture and the wider environment. Thus, it is important to understand the areas within a catchment where NPSP risk is higher enabling the establishment of monitoring and/or mitigation procedures. The models support the ecosystem approach to aquaculture (EAA) and enable objective planning and management strategies to enhance productivity across large catchments without negatively impacting the environment. In order to meet growing food requirements, large areas will need to be used for agriculture and aquaculture; therefore, analysis at a wider catchment level, which complements assessment at a local scale, is required as it allows a holistic view of the situation. The work presented here illustrates the potential use of spatial models across large catchments and considers the suitability of the areas for aquaculture development.

published_or_final_version / abstract / Geography and Geology / Master / Master of Philosophy

<p>Dental caries is a multi-factorial disease that affects everyone irrespective of race, class or gender, however, the burden of the disease is often found in children from lower socio-economic backgrounds. The nature of the disease is such that it can be prevented. Various international studies on fluoride have shown a reduction in the prevalence of dental caries. By using geographical information systems, oral health data can be linked to the fluoride levels and further analysis could be done to identify areas at risk of dental caries as well as show patterns in the distribution of dental caries. The aim of this study was therefore to assess the effects of different levels of fluoride on the prevalence of dental caries in selected towns in the Northern Cape and Westen Cape. It also examined the application of Geographical Information Systems (GIS) to oral health data.</p>