Copyright © IFAC Artificial Intelligence in Agriculture, Wageningen, The Netherlands, 1995 EXGIS: AN EXPERT GEOGRAPlDCAL INFORMATION SYSTEM FOR LAND EVALUATION C. P. Vialoaris I, V. Kollias 1, N. A. Loreatzos I, D. Kalivas 1 , A. B. Sideridis l (J) In/ormaties Laboratory (2) Soils Laboratory Agricultural University 0/ Athens 75 Iera Odos, J 1855 Athens Greece Abstract : An Expert Geographical Infonnation System, (EXGIS), is presented, developed for the evaluation of natural resources. EXGIS has been based on a specially implemented shell, which can manipulate knowledge concerning the procedures of land evaluation. This shell collaborates with the Geographical Infonnation System PC ARCIINFO. EXGIS combines the capabilities of an Expert System, concerning the reasonable selection of areas which are suitable for a certain land management as well as the capabilities of ARCnNFO, in the process of setting the exact limits of these areas, their geographical treatment and their representation in map fonn. EXGIS uses spatial and conventional data. These data are stored in the spatial database of ARCnNFO and other conventional databases which are connected with the GIS. The stored knowledge, which the Expert System uses, enhances the whole system with the capability to answer complicated questions concerning procedures and management related with natural resources. Keywords: Expert systems, geographical infonnation systems, land evaluation. 1. INTRODUCTION Since the mid 1970's, Expert Systems (ES) have been used in a variety of application areas. One such area is the evaluation of natural resources (Loh et al., 1994). In particular, evaluation procedures are stored in a knowledge base and are used by ES (Pereira, et al., 1982; Rossiler, 1990; De la Rosa, et al., 1992). At the same time, a Geographic Information System (GIS) has to be used, to process and display spatial data. The present paper concerns an Expert Geographical Information System, EXGIS, which combines the capabilities of a commercial GIS, PC ARCnNFO ver. 3.4., with those of a rule-based ES. This ES has been based on a specially developed shell, which satisfies certain requirements, dictated by 85 the Greek agricultural extension services (yialouris, 1994). It has been implemented in CLIPPER because the files produced by the latter (DBASE III+ files) can subsequently be processed by ARCIINFO. EXGIS is currently running under DOS. As opposed to known commercial ES, it is disk resident, hence its operation is not limited by the available amount of primary storage. EXGIS was used as a tool for land evaluation, in order to determine its functionality. This decision was based on the following factors: Firstly, the amount of Greek land, which is suitable for agricultural use, is 13%, therefore, the identification of the optimum land use, for sustainable agriculture, has a major practical