Comparison of stochastic and deterministic methods for mapping environmental noise from opencast quarries

An accurate mapping of the acoustic spatial variability generated by quarrying plants constitutes an important step in the assessment of the environmental compatibility of the extraction site with the surrounding area. This paper refers to the results of a study comparing performances obtained by stochastic and deterministic methods to determine the acoustic climate of the areas surrounding opencast quarries. To this aim noise levels are monitored in the areas surrounding a limestone quarry site in central Italy. In the first phase an analytical prediction model, based on ISO 9613 and ISO 3746, is developed using the sampled sound power level of each source as input data. In the second phase, in contrast, the stochastic method of Ordinary Kriging is used to plot an acoustic map. This is drawn up by interpolating the scattered sound pressure level data from sampled points which are identified as nodes of a rectangular grid covering the chosen area. The analytical prediction model output, which consists in the sound pressure level at various target points, is then compared with the homologous map obtained from the Ordinary Kriging method. Finally the resulting maps are evaluated with respect to statistical measures and cross validation procedures in order to determine the most suitable method.