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Computerized land evaluation systems and geographic information systems
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40 2019 ND-CP 413905
| Computerized land evaluation systems and geographic information systems
Some computerized land evaluation systems use statistically derived and analytically applied land use models, while others use qualitative impact assessment approaches based on expert opinion and rules. Geo-information technology has offered the scientific means to satisfy the demand for quantified spatial information on land resources, e.g. pedometrics to meet the requirements for quantitative spatial soil information (Webster 1994). Geographic Information Systems (GIS) have greatly improved spatial data handling (Burrough and McDonnell 1998), broadened spatial data analysis (Bailey and Gatrell 1995) and enabled spatial modelling of terrain attributes through digital elevation models (Hutchinson 1989; Moore et al.,1991). The advent of GIS has brought about a whole set of new tools and enabled the use of methods that were not available at the time when the 1976 Framework was developed. The automated land evaluation system (ALES; Rossiter 1990) is a computer program that allows land evaluators to build their own expert systems to evaluate land according to the framework for land evaluation (FAO 1976). ALES is a framework within which evaluators can express their own knowledge for use in projects or regional scale land evaluation, taking into account local conditions and objectives. The entities evaluated by ALES are map units, which may be defined either broadly, such as in reconnaissance surveys and general feasibility studies, or narrowly, such as in detailed resource surveys and farm-scale planning. Since each expert system is built by a different evaluator to satisfy local needs, there is no fixed list of land use requirements by which land uses are evaluated, and no fixed list of land characteristics from which land qualities are inferred. Instead, these lists are determined by the evaluator to suit local conditions and objectives. The framework also allows estimation of land qualities by pedotransfer function or simulation model (Bouma et al., 1996). Process-based models have been used to evaluate particular land qualities such as soil moisture regime (Bouma 1989) and solute leaching (Hutson and Wagenet 1992; Feyen et al., 1998). Other systems, developed before the era of GIS, such as LESA, currently have been integrated with GIS (Hoobler et al., 2003). |