1 The GIS approach to detect the influence of the fresh water inflows on the marine-coastal waters: the case of the Apulia Region (Italy) through standard monitoring data A. Porfido, E. Barbone*, V. La Ghezza, G. Costantino, V. Perrino, N. Ungaro, M. Blonda. ARPA – Agenzia Regionale per la Prevenzione e la Protezione dell’Ambiente, Corso Trieste 27, 70126 Bari, Italia. *Corresponding author: e.barbone@arpa.puglia.it Abstract: The water quality in the marine coastal areas is affected by “natural” features (geo- morphology, hydrology) as well as by the “human” use of land. Understanding the linkage between water quality and river catchments is fundamental for the evaluation of different options in the coastal zone management. Monthly monitoring surveys were performed by ARPA Puglia during the January 2008-December 2009 period, both in the Adriatic and Ionian Seas. Spatial and temporal patterns of water chemical-physical parameters and the trophic index (TRIX) were investigated using the GIS approach for the evaluation of the influence of freshwaters inflows on the coastal area. The results indicate the effectiveness of standard monitoring activities in the water quality control and the usefulness of the GIS tool in order to detect the influence of the river’s runoff. Keywords: GIS, mixed effect modeling, TRIX, coastal water, river runoff 1. Introduction The coastal zones are areas where natural processes (change in precipitation inputs, erosion, weathering of terrain materials) as well as anthropogenic influences (urban, industrial and agricultural activities) are concentrated (Focardi et al, 2009). Among the anthropogenic activities, are worth of notice the over-utilization of groundwater resources, the pollution and discharge of wastewaters into the sea. Particularly, the rising water demand from agriculture in Southern Italy, an area with a natural water resource scarcity, leads to the accumulation of nutrients in river basins. An overall quantitative estimate of nutrients loadings runoff to the Mediterranean sea is reported by Strobl et al. (2009). Mixing between inland and coastal waters represents a key process for biological productivity, with strong implications for the whole coastal system functioning and ultimately on the fishery. For this reason, the understanding of linkage between river catchment and water quality in the associated coastal zone is fundamental for evaluation of different options in the integrated coastal zone management. The purpose of this study is to investigate the influence of the freshwater inflows on the marine-coastal waters of the Apulia Region by mean of GIS approach. Standard water monitoring surveys were performed by ARPA Puglia during January 2008-December 2009 period along Apulian coasts. Spatial and temporal surface distribution of TRIX index (Vollenweider et al., 1998) was examined to evaluate the trophic status and surface quality of the coastal water and was studied in relation to the physical (salinity) and biological (Chlorophyll a) parameters.