Levantamento da vulnerabilidade dos recursos hídricos subterrâneos no município de Dona Francisca RS

Abstract

The correct use and administration of the natural resources are of fundamental importance for the economical development and well to be social of a nation. The main objective of the work is the analysis of the natural vulnerability of the ground waters in the municipal district of Dona Francisca/RS. For this the model DRASTIC was used. This model is subdivided in seven factors, which are: D = depth of the static level; R = total recharge; A = half aquifer; S = soils; T = Topography; I = impact in the vadose zone; C = hydraulic conductivity. To this group of factors weights are attributed in agreement with the reduction capacity of pollutant that each it possesses. That is done in the intention of quantifying a called value of potential index of pollution. The vulnerability indexes suggested by the model extend of <35 (protected area) up to >120 (obligatory protection area). In the Municipal district of Dona Francisca, Rio Grande do Sul State southern of Brazil. Was arrived to indexes contained in the intervals of 65 - 95 (vulnerable area 38% of the total), high vulnerability in the interval 95 120 (38% of the total area) by last bigger than > 120 (obligatory protection area 10%). They were simulated 21 wells, being 12 of the type manual drilled and 9 of the tubular type. They were spaced in GIS (Geographical Information System) with the use of the software Surfer 8 the following parameters: electric conductivity, total dissolved solids (TDS), potentiometric surface and the vulnerability index. Through the software Spring 4.1 were mapped the use of the earth, the geology and the steepness of the land. Starting from the mapping of the potentiometric surface was verified a tendency of ground water flow of northwest to southeast. Through the rising of the natural vulnerability of the mapped area can be defined the use and occupation of the soils location and potentiality contaminant activities dispose in this area of 104 Km2.