Expert system for evaluating the Environmental Sensitivity Index (ESI) of a local area.

Considerable amounts of data are required in order to estimate the Environmental Sensitivity to desertification of a particular area. Data alone, however, is useless without appropriate tools for their efficient exploitation. In terms of tools - sophisticated techniques must be used to acquire and manage the large amounts of spatial and temporal data. These data, which are becoming ever more complex and which produce heterogeneous information layers with different levels of detail, are necessary to solve the crucial and intricate problems of today. In terms of data - three different types of information are essential for estimating the Environmental Sensitivity to desertification: physical-structural, vegetal, and socio-economic. These categories are not necessarily independent: remotely sensed radiometric data and vegetation or phytoclimatic maps, are all influenced by different factors from many different origins. Data can be obtained from available documents or obtained by dedicated surveys where costs depend on the ease with which they are obtained. They can be nominal (e.g. crop data, crop type, and forms of tillage), presence or absence, ordinal, discrete (e.g. a pedological system, soil water, or organic matter content), or continuous (e.g. information from a Digital Elevation Model) to name but a few. The complexity of the information is related to the sophistication of the questions that have to be answered; yet the combination of different data and complex questions means that the data have to be analysed in an integrated way to extract succinct, and well founded, answers (De Jong, 1994; Ferrara et al., 1995; Yassoglu et al., 1995). In this context, a comprehensive system was developed to evaluate and investigate the causes and responses which contribute to the Environmental Sensitivity to desertification of each fundamental land unit describing an Environmental Sensitive Area (ESA). The coverage of the scheme ranges from the local to basin-wide scales. The system presented here is an expert application of this system, presented as a web-based tool to enable the Environmental Sensitive Index to be determined for individual areas. In the system data from many different sources, such as qualitative and quantitative satellite radiometric measurements, available geographical data, and ad hoc ground surveys, can be integrated.