Land uses simplified index (LUSI): A simple method to asses continental pressures on coastal waters

55 Conference Estuarine Coastal Sciences Association (ECSA 55), Unbounded boundaries and shifting baselines: Estuaries and coastal seas in a rapidly changing world, 6-9 September 2015, LondonThe DPSIR (drivers-pressures-state-impact-responses) framework is used to analyze the causal relationships between environmental and human systems and to report on environmental issues. The effective use of the DPSIR approach requires the accurate assessment of pressures. For coastal waters, although several methods have been evaluated, most of them are complicated or require large amounts of data. Here we present a novel method, the Land Uses Simplified Index (LUSI). The rationale of LUSI is based on the following assumptions: 1) Coastal waters receive pressures mainly from continental fluxes. 2) Coastal land uses determine the amount and nutrient richness of continental fluxes. 3) An area of riverine input into coastal waters is influenced by the complete range of uses of the respective watershed. 4) Coastal morphology has an effect on coastal water confinement and thus on received pressures. The LUSI algorithm combines categorized information on land uses (urban, industrial, agricultural, and riverine) that influence coastal waters and on the morphology of that land in terms of its ability to enhance or diminish these influences. A low LUSI value indicates that the coastal water area is not or only slightly influenced by continental pressures whereas a high LUSI value indicates a strong influence of continental pressures. Among the many advantages of LUSI are that it is easy to use, fast, cost-effective, repeatable, and yields comparable results among coastal areas. These characteristics recommend the use of LUSI within the DPSIR framework and in the implementation of environmental policies at the European level. For example, in accordance with the Water Framework Directive (2000/60/EC), LUSI (calculated using CORINE land cover) was able to demonstrate pressure-impact relationship for phytoplankton in Catalan coastal waters, NW Mediterranean (chlorophyll-atransformed=0.109*LUSI+0.208; R2=0.608; p=8.18e-05). These aspects of LUSI as well as the challenges in designing methodologies that balance simplicity with accuracy are discussed hereinPeer Reviewe