Support method for interpretation of regional groundwater monitoring in urban areas

Fabio Pileggi,Bruno Conicelli,Ricardo Hirata,Nataly Aranda

doi:10.1590/2317-4889202120200053

Fabio Pileggi, Bruno Conicelli + Show 2 more

Open Access

https://doi.org/10.1590/2317-4889202120200053

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Abstract

Abstract Urban centers radically alter hydrological cycles, causing unintended consequences for the environment, such as the creation of extensive contamination plumes in unconfined aquifers. The Environmental Agency of the State of Sao Paulo has observed this issue since 1994. Therefore, this study aimed to create a method using nitrate as an indicator of contamination that permits an assertive interpretation of changes in the groundwater quality in monitoring wells of regional networks. The method was applied in ten cities with monitoring wells in the Bauru Aquifer System. The results correlated the presence of nitrate with the time and dynamics of land use in the capture zones of the wells over 54 years (1962-2016). In areas with sewer networks installed before 2001 and urban occupation greater than 60% of urban occupation in the capture zones, there was an increase in nitrate concentration of at least 35%. Likewise, extending this new method to other wells will make it possible to identify the causes of nitrate and other contaminants in the groundwater-monitoring network in the State of Sao Paulo.

Highlights

Cities have radically altered the flow of water, energy, and matter from river basins
The results revealed three types of behaviors overtime (Tab. 3): three wells with a tendency toward decreased concentration (Cajobi, Murutinga do Sul, and Pompéia); a well showing stable behavior (Inúbia Paulista); and six wells with a tendency toward increased concentration (Andradina, Clementina, Florida Paulista, Jales, Nova Independência, and São José do Rio Preto)
In all the studied cities, the urban density in the capture zone area increased between 132% (Inúbia Paulista) and 730% (São José do Rio Preto)

Summary

Introduction

Cities have radically altered the flow of water, energy, and matter from river basins. Various urban activities transfer immense amounts of matter from the atmosphere (Babinski et al 2003, 2012) and from the surface to the soil (CETESB 2013, Santos Filho et al 2017, Aranda et al 2019), rivers (Porto 2003, Xu et al 2019), and aquifers (Foster and Hirata 1988, DAEE 2012, Cary et al 2013, Conicelli 2014, Bertolo et al 2015, Hirata et al 2015, Petelet-Giraud et al 2018), sometimes contaminating them. No studies have explained the causes behind the increase of nitrate concentrations in the monitoring network over time; and reports have only attempted to describe the problem

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