FPI, a flexible index for surface water pollution measurement

In this paper, a new index for water quality rating, based on a combination of the average and the maximum value of any number of parameters, is put forward. The index satisfies the following basic requirements: globality of water dimensions, sensibility to pollution variations, robustness to time and spacial unexpected fluctuations, flexibility, i.e. distributional stability, both to missing information and to indicator substitution. The index parameters were estimated with the aim of measuring the quality of a freshwater stream for acquatic life and wildlife. To parametrize the index, 11 Italian experts on environmental protection were surveyed with a Delphi-type procedure. The experts were asked to select the relevant variables and determine their weights for harm risk evaluation. In this paper, the properties of the index are evaluated by performing several jackknife applications on real data. Monitoring data collected in the Province of Rovigo (Italy) were used for index distributional properties evaluation.