Proposal for the classification of potential pollution sources for groundwater contamination

Abstract

The identification of activities with the potential for groundwater contamination aids in the prioritization of actions to protect water resources, especially in areas with significant urban and economic development. This study presents a survey of potential pollution sources in the municipalities of Capivari, Elias Fausto, Indaiatuba, Monte Mor, Rafard and Salto (State of São Paulo) and proposes a classification of the associated contaminant load in order to identify the areas of highest hazard of groundwater contamination in this region. The classification developed here is called POSH-IG and is adapted from the renowned POSH (Pollutant Origin, Surcharge Hydraulically) method, which ranks the contaminant load of the potential pollution sources in three qualitative levels (low, moderate and high) based on the origin of the contaminant and the presence of a hydraulic surcharge promoting advective transport to the aquifer. In the POSH-IG method adjustments were made for the classification of the contaminant load of point sources, inserting available parameters from the Environmental Licensing System of São Paulo State. Land use mapping, the type and pattern of occupation was integrated to classify the contaminant load of diffuse pollution sources associated with sanitation systems in urban areas and farming and livestock activities in rural areas. Besides the evaluation of urban expansion areas, the density of occupation of residential, commercial, and services areas - an indirect indicator of population density - was also considered as a criterion for classification of diffuse sources related to sanitation systems. Of the 1918 point sources of contamination registered in this study, the activities with highest contaminant load are mainly related to the chemical, metallurgical, metal product, electronics and mechanical engineering industries, storage of hazardous products and inadequate waste disposal. In urban areas the greater potential contamination load from diffuse sources is concentrated in the older portions of the cities where higher occupation densities occur. The largest such areas occur in the municipalities of Indaiatuba and Salto, where there has been intense urbanization and in Monte Mor, where less than 45% of the city is servedby the sanitary system. In rural areas, sugar cane cultivation, prevalent in the municipalities of Capivari and Rafard, stands out because of its high potential for groundwater contamination.