Abstract Incomplete information is one of the main constraints for decision-making, which are then by definition risky. In this study, formal risk concepts were introduced in decision-makersÕ meetings according to local demands and following a participatory approach, as a first step towards integrating risk assessment into rural decision-making in Santa Catarina, Brazil. Semi-structured interviews and meetings were conducted with extensionists and farmers. The following information was presented and discussed: (1) the time series and frequency distribution of maize yield predictions, simulated by the GAPS computer program for 16 feasible planting dates, representing climatic risks, both within and between years; and (2) a simple economic analysis (gross margin) and income probabilities for seven land-use options over a recent five-year period, followed by an interactive exercise where probabilities of achieving user-supplied target gross margins were calculated according to participantsÕ actual information, using the computer program @RISK. This paper also investigates decision-makersÕ attitudes towards risk, and how these were influenced by objective information. Although results AGRICULTURAL SYSTEMS from a study such as this are not definitive, considering that the effects of the information on actual decision-making require some time to become evident, it was already possible to conclude that the risk-orientated information presented according to local demands and following a participatory approach had a positive impact on decision-makersÕ understanding and perceptions. This approach should be further explored to effectively integrate risk assessment into rural decision-making. 0308-521X/$ -see front matter

Several conceptual models and data models have been proposed for geographical phenomena with uncertainties that cannot easily be forced into current standard data models. These models of uncer-tain objects can be categorized into two groups. One group (Clementini and Di Felice 1996; Cohn and Gotts 1996; Roy and Stell 2001) considers the broad boundary of an object as a homogeneous two-

ter verkrijging van de graad van doctor