Evaluation of methods for ewlhead protection areas for the State of São Paulo


The perimeters of protection wells play an important role in protecting the quality of groundwater exploited for public water supply. There are several methods which define the dimensions and shapes of zones of contribution, ie the area where the whole surface aquifer recharge is captured by the well, and areas based on transit times, defined in time when a particular contaminant may reach the well. Both zones allow control of land use in order to protect the catchment. This paper presented a comparative study of three different methods in different aquifers of the State of São Paulo. The methods studied were fixed radius calculated based on cylinder technique that uses volumetric flow equation; analytical model, using the uniform flow equation, and numerical model, by means of mathematical models for flow simulation. The results showed that each method has generated different areas both in shape and in dimensions. The first two methods defined sizes of zones of contribution similar but with different formats and about 200% greater than those defined with the same numerical hydrogeological conditions. From the results, it appears that the use of the analytical method is feasible on a first assessment since data for this are already available for nearly all public supply wells of the state and its accuracy is higher than the calculated fixed radii method. Already at a later stage, in which the zones of contribution is most sensitive, the numerical model would be the natural choice.


CARVALHO, Ana Maciel de; HIRATA, Ricardo. Avaliação de métodos para a proteção dos poços de abastecimento público do Estado de São Paulo. Geologia USP, Série Científica, v.12, n.1, p.53-70, abr., 2012.

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