Combining natural and anthropic atributtes for aquifers contamination potential in southeast of Brazil

Costa, Carlos Wilmer; Lorandi, Reinaldo; Lollo, José Augusto Di; Serikawa, Vagner de Souza

doi:10.14393/SN-v32-2020-56221

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Papers • Soc. nat. 32 • 2020 • https://doi.org/10.14393/SN-v32-2020-56221 copy

Combining natural and anthropic atributtes for aquifers contamination potential in southeast of Brazil

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

The compromise of surface water resources' quantity and quality, as well as the extensive use of groundwater, exposes aquifers to contamination risks. Considering this, combine natural and manmade influences is a proper strategy for potential aquifer contamination evaluation. This article presents charts of aquifer contamination potential in Rio Claro watershed (251,91km², in Santa Rita do Passa Quatro, SP) at 1:50,000 scale, taking in account aquifer units, surface geology units, soil and steepness information; operated using multicriteria analysis. The classes “Very high” and “High potential” where the most representative classes of contamination potential in the watershed (performing 46.1% in 1994 and 48.6% in 2014). Obtained contamination potential expressed geological attributes influence in the area. Land use / land cover changes were determinant for higher potential maintenance with time. Adoption of land use / land cover control measures and improvements in tillage management are alternatives for the groundwater protection in this watershed.

Keywords:
Groundwater; GIS; Multicriteria analysis; Geo-environmental attributes

Unit	Era Period	Description
Alluvial Deposits	Cenozoic Holocene	They are represented by wide plains that occur along the bottom of the Rio Claro valley and main tributaries. They consist of alluvial and colluvial sediments with a sandy texture due to the contribution of adjacent lithologies.
Piraçununga Formation	Cenozoic Tertiary	It is composed of light brown sandy-clayey sediments without very poorly selected sedimentary structures. At the base, it usually presents a line of pebbles or gravel, with quartz and quartzite pebbles and fragments of limonite, overlapping discordantly over the Corumbataí Formation.
Santa Rita do Passa Quatro Formation	Cenozoic Tertiary	They consist of sands in a clayey matrix, without sedimentary structures with basal gravel pebbles predominantly of quartz. In the area, these sediments are brown in color, very friable and have quartz granules dispersed throughout the thickness, which varies from a few cm to a few meters with a wide horizontal distribution (MASSOLI, 1981MASSOLI, M. Geologia do Município de Santa Rita do Passa Quatro, SP. Revista do Instituto Geológico, v. 2, n. 2, p. 35-45, 1981.).
Serra Geral Formation	Mesozoic Cretaceous	They are regionally constituted of sills and dikes of basic magmatites, of phaneritic texture and gray to black color, presenting intensely fractured and dense aspect. In aerial photographs, they have dark gray tones, steep slopes and preferential distribution along interfluves.
Botucatu Formation	Mesozoic Jura / Cretaceous	Consisting predominantly of aeolian sandstones attributed to deposits in a desert environment, with fine to medium grain, well rounded particles and essentially quartz composition (80%), the thickness varies between 20 and 280 meters. It has a large number of interconnected pores and a high capacity to store and supply water.
Pirambóia Formation	Mesozoic Triassic	Composed of whitish, yellowish and pinkish river sandstones, medium to fine, sometimes quite clayey, due to stratigraphic positioning. In aerial photographs, they present light gray to white shades, with a poorly developed drainage system, with dendritic pattern.
Corumbataí Formation	Paleozoic Permian	Regionally composed of variegated shales, being positioned between the Irati (lower) and Pirambóia (upper) formations. In aerial photographs, print dark gray tones and high drainage density with feather pattern.

Soils	Area (km²)	Thickness (m)	Granulometry (%)*			Permeability coefficient (cm/s)
Soils	Area (km²)	Thickness (m)	Cl	S	Sa
Quaternary	15.87	<2, 2-5	5	4	91	6.1 10^-3
Res. Santa Rita do P. Quatro	45.72	>5	14	8	78	3.7 10^-2
Res. Piraçununga	11.38	>5	28	7	65	4.2 10^-3
Res. Botucatu	17.65	<2, >5	20	5	75	3.8 10^-3
Res. Pirambóia	11.38	<2, >5	24	6	70	7.1 10^-3
Res. Magmatitos Básicos	26.48	<2, 2-5, >5	47	17	36	4.9 10^-4
Res. Corumbataí	19.65	<2	77	9	14	4.1 10^-4

CROSSING 2		Soils (thickness)
CROSSING 2		(>5m)	(2 - 5m)	(<2m)
Result 1	Very Low - 1	1	2	3
	Low - 2	1	2	3
	Average - 3	2	3	4
	High - 4	3	4	5
	Very High - 5	4	5	5

CROSSING 3		Slopes
CROSSING 3		> 20%	10 - 20%	5 - 10%	2 - 5%	0 - 2%
Result 2	Very Low - 1	1	1	1	2	3
	Low - 2	1	1	2	3	4
	Average - 3	2	2	3	4	4
	High - 4	3	4	4	5	5
	Very High - 5	3	4	5	5	5

CROSSING 4		Land use and coverage
CROSSING 4		Sugarcane	Water	Other uses*	Pasture	Exposed soil	Native vegetation	Urbanized area
Result 3	Very Low - 1	2	3	2	1	2	1	2
	Low - 2	3	3	2	2	3	1	3
	Average - 3	4	4	3	3	4	2	4
	High - 4	5	5	4	4	5	2	5
	Very High - 5	5	5	5	5	5	3	5

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[TFN1] Org.: The Author, 2020.