A comparative appraisal of four proposed GIS-based methodologies to map anthropogenic cumulative effects at a landscape level in Ireland

Cumulative Effects Assessment, a requirement under European law, refers to the analysis of accumulated environmental change resulting from past, present and future human activities. Despite the legal requisite, and its potential to better address and mitigate environmental degradation, assessment of cumulative effects is a key deficiency in current environmental assessment practice – mainly due to the disparity in definitions and divergence in methodological approaches. To address the current lack of systematic methods and tackle some of the identified methodological shortcomings, intuitive yet innovative approaches based on Geographic Information Systems have been developed to examine potential cumulative effects at a landscape level. The approaches are tailored to tackle specific considerations such as direct and indirect effects on the receiving environment or on specific valued components. This paper demonstrates them and comparatively appraises their applicability. While further studies are required, pilot testing of these methods have validated their practical implementation and, more importantly, their potential to enhance current Irish practice by enabling systematic preliminary desk-based assessments of potential cumulative effect areas, thus facilitating better environmental management and evidence-based planning decisions.