Geostatistical Assessment of Sewage Outfall Discharges

Abstract- Geostatistical techniques were used to study the spatial continuity of the salinity of a sewage outfall discharge. The data set used was obtained in a monitoring campaign to a sea outfall, located off the Portuguese west coast near Aveiro region, using an Autonomous Underwater Vehicle. The spatial analysis package geoR was used for computing variograms and ordinary kriging. The robust estimator was used to compute the experimental semivariogram, which was fitted to spherical theoretical model, after a successful cross-validation. The prediction maps of the spatial distribution of salinity show clearly the effluent plume dispersion in the field. This study suggests that geostatistical methodology can provide estimates of effluents dispersion very valuable for environmental impact and management of sea outfalls. I