Most previously developed coastal vulnerability/sensitivity indices acknowledge that the addition of socio-economic variables would assist in defining vulnerable areas. This study investigated the incorporation of socio-economic variables into a GIS based coastal vulnerability index for wave-induced erosion in Northern Ireland.

In this application, a socio-economic sub-index was developed to contribute potentially one third of the overall index score; the other components consisted of coastal forcing and coastal characteristic sub-indices. All variables were ranked on an arbitrary 1–5 scale with 5 being most vulnerable. The variables were merged within sub-indices and then the sub-indices were combined to produce the overall index.

Several problems were encountered in assessing socio-economic vulnerability indicators. These relate to the inherent difficulties involved in ranking socio-economic data on an interval scale. Temporal aspects also caused difficulties as socio-economic variables vary over time as coastal populations and policies change. There were also problems in relation to the size of the unit used to display the data and how this affected the vulnerability of certain areas. Larger, more fundamental, problems in relation to human perceptions of vulnerability were also investigated. The final results of the combined index were tested against field and desk-top studies and although they correlated well with expected outcomes, the results did suggest an under representation of the socio-economic index. Suggestions are put forward to alleviate this problem in any future developments.