Exploring the impact of map uncertainty on soil sealing versus conservation decisions

Incorporating soil quality into land-planning decisions is considered a crucial initial step in minimizing the environmental and human well-being impacts of soil sealing. In recent years, land planners have gained greater access to soil quality maps and, in the best cases, to their associated uncertainty. However, it remains unclear how the representation of map uncertainty influences decision-making, and how this influence varies depending on the decision to be made (conservation/conversion) and land-planners’ backgrounds or socio-demographic characteristics. This paper presents the results of a map-based survey, in which respondents were shown soil quality maps with varying levels and representations of uncertainty, and asked to make either sealing or conservation decisions. We determined through a statistical analysis how the different factors (level of uncertainty, map resolution, type of visualization, self reported comfort, expertise, etc.) influence decision-making, and how their influence varies across decision scenarios (sealing vs. conservation). We showed that the main factors at play are soil quality and uncertainty level. Their effects, however, depend on the decision scenario. We also demonstrated that end-users were able to incorporate uncertainty information into their decisions, and quantified, in each scenario, the threshold above which uncertainty impedes decision-making. These results highlight the impact of map uncertainty on planners’ decisions and underline the need for clear representation, as many environmental maps used in land planning are inherently uncertain.