Vulnerabilidade natural de aquíferos e potencial de poluição das águas subterrâneas

Abstract

A widespread attitude exists of underestimating the risks of pollution of the groundwaters that it opposes to the growth of its use; this situation increases its risk of contamination. Like this, the work had as general objective to determine areas susceptible to the contamination of the groundwaters in Santa Maria's Geographical Micro region; and as specific objectives to collect data, to establish the natural vulnerability of the aquifers, to identify the pollutant activities and to represent cartographically the obtained information. A database was elaborated with information of the 345 registered wells (SIAGAS/CPRM) and the method GOD was applied (Foster and Hirata, 1987) considering Groundwater degree of hydraulic confinement, Occurrence of the litology substratum and Depth of the groundwater level. It was verified that the area presents fragile natural structure, prevailing the classes of High and Extreme vulnerability. The identified socioeconomic activities through consultations to the Base of Municipal Information (IBGE, 2002) they refer to the agricultural and cattle production. It was ended that the groundwaters in Santa Maria, Cacequi, São Sepé, Itaara, São Pedro do Sul, Nova Esperança do Sul, São Vicente and Jaguari are more susceptible the contamination for activities of the urban-residential section. While in Dilermando de Aguiar, Mata, São Martinho da Serra, Toropi and Vila Nova do Sul the risk of contamination is linked to the activities of the rural section. Those activities can alter or to induce new recharge mechanisms, the understanding of those mechanisms and the correct evaluation of such modifications is fundamental, because the polluting load can be controlled or modified, not happening the same with the natural vulnerability of the aquifer (Foster and Hirata, 1993).