Assessment of coastal vulnerability to land-based sources of pollution and its application in Apulia, Italy

: The present paper deals with the assessment of the coastal vulnerability to pollution sources induced by land-based activities (LBAs). The coastal vulnerability is expressed and evaluated in relation to the land-based activities present in the coastal areas and a new index, namely Coastal Pollution Index from land-based activities (LBAs_index), is proposed. The index is calculated considering nine indicators using a transect-based approach. The nine indicators refer to point and non-point sources of pollution, and include: rivers quality status, seaports category, airports category, wastewater treatment facilities/submarine outfalls, aquaculture/mariculture areas, pollution load of urban runoff, type of artisanal/industrial facilities, farm/agriculture areas, type of suburban roads. Each indicator is quantified by means of quantitative scores, whereas the strength of cause-effects relationship is assessed by assigning weights using the Fuzzy Analytic Hierarchy Process approach (F-AHP). The indicators are then aggregated to obtain a synthetic index and classified in five categories of vulnerability. The main findings of this study include: i) the identification of key indicators of coastal vulnerability to LABs; ii) the development of a new index to identify the coastal transects where the effects of the LBAs may be the greatest. The paper explains the methodology for the index computation, and illustrates it with an application in Apulia, Italy. The results demonstrate the feasibility of the index and its usefulness to identify the most critical areas in terms of land pollution sources and to produce a vulnerability map. The application allowed to have a synthetic picture of the threat of pollution from LBAs, facilitating its analysis and the benchmarking between the transects. Regarding the case study area, results show that low vulnerability transects are characterized by small agricultural areas/artisanal activities and small urban areas, whereas in very high vulnerability transects all indicators assume high scores.