Problems associated with irrigation in humid regions include uncertainty of whether irrigation will be necessary in a given year, and the question of whether crop response will be sufficient to make the required investment profitable in the long run. A prototype knowledge based system (KBS) has been developed to determine the economic feasibility of a range of irrigation systems for site specific conditions. The KBS uses information input by the user to determine possible irrigation alternatives and provides an economic evaluation of suitable systems based on domain-specific knowledge about soils, crops, irrigation costs, and agricultural drought in Virginia. Irrigation systems considered by the KBS include center-pivot, traveling gun and portable pipe systems. Crops considered are field corn, soybeans, and peanuts. Preliminary evaluation showed that the KBS was able to effectively determine if portable pipe, traveling gun and center pivot irrigation systems were suitable, and provide an economic evaluation of these systems for site specific situations in Virginia. The KBS developed in this study provides a basic framework which can be used to build a more comprehensive system which would address a larger domain, considering additional systems and crops. / Master of Science