Department of Geography and Environmental Studies

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Browsing Department of Geography and Environmental Studies by browse.metadata.advisor "Carey, Victoria"

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    The Identification of natural terroir units in the Robertson Wine District using GIS and remote sensing
    (Stellenbosch : Stellenbosch University, 2012-03) Remas, Hadley; Van Niekerk, Adriaan; Carey, Victoria; Stellenbosch University. Faculty of Arts and Social sciences. Dept. of Geography and Environmental Studies.
    ENGLISH ABSTRACT: One of the main objectives of the South African Wine of Origin Scheme (SAWOS) is to guarantee the quality of wine products emerging from South Africa’s viticultural production areas by preventing the abuse of names of products originating from outstanding viticultural areas. The study of terroirs contributes to knowledge that assists in delimiting potential viticultural areas in South Africa. Terroirs are areas with homogeneous groups of natural factors that, with the aid of effective management, have the potential to produce a unique product over a recognizable period. Natural terroir units (NTU) reflect the integration of relatively homogenous environmental factors, which include topography, climate, soil and geology. This study investigates the use of geographic information systems (GIS) and remote sensing methods in the identification of NTU in the Robertson wine district. Existing topographical, soil, geological and climatic GIS data layers were collected at various scales. In addition to this spatial data, orthorectified and radiometrically corrected SPOT 5 and ASTER satellite imagery were used to classify the land use/cover using an object-based image analysis (OBIA) approach. Eight land use/cover classes were distinguished by a sequential ruleset and an overall accuracy of 81.2% was achieved. The land use/cover layer was combined with the slope aspect and soil landscape to provide a three-component NTU description. One hundred and seventy NTU were identified, of which fifty five units exist for agriculture. These NTU can be used for site selection of agricultural produce and effective planning and management of land use. Climate was not included in the delimitation of NTU because the coarse resolution of climatic data could not be used to distinguish between different NTU. Therefore, all NTU identified in this research has similar climatic conditions. The major drawback of GIS-assisted terroir studies is the difficulty of representing a number of NTU on one GIS map. Therefore, it is recommended to associate the NTU map with a table of the classes instead. Furthermore, the accuracy, scale and resolution of available GIS data in South Africa influence the delimitation of NTU. Although remote sensing was found to provide efficient methods for land cover mapping, the use of multiseasonal satellite images would classify vineyards more efficiently because such an approach accounts for the different growth cycles of grapevines.