Find out the dangers of groundwater exploitation and how Brazil has taken steps to mitigate this issue during its water crisis.
In times of drought or water shortage, organisations and individuals will resort to various methods of obtaining water. Uncontrolled exploitation of groundwater is an issue that can cause contamination and pollution, as well as the lowering of water table, decreased flow of rivers and even the drying of lakes.
The water crisis in the southeast of Brazil, which has led to increased demand for groundwater wells, highlights the dangers of this issue.
According to the Groundwater Research Center (CEPAS) of the University of São Paulo (USP), 400 wells were drilled in the Metropolitan Region of São Paulo (RMSP) from January to October 2014. A study by CEPAS has indicated that 40% of the metropolitan area’s aquifer capacity is idle. This volume is enough to supply 520 million litres per day, enough for the needs of 1.8 million people.
The Department of Water and Electric Energy (DAEE) division responsible for granting and supervising the use of water resources recorded 2,134 granted wells in the state capital and 24,699 granted wells across the state of São Paulo. However, the Brazilian Groundwater Association (ABAS) believes granted wells represent only 30% of existing wells in the state and just 10% in Brazil as a whole. Licenses can cost as much as $3,000 and well construction can cost around $35,000 - $110,000; this, together with delays of up to a year in awarding the grants and the lack of government surveillance, can account for the large number of illegal wells.
This situation is worrying because the construction of illegal wells does not follow the requirements of technical standards. As a result, these wells may draw water from shallower aquifers, which have high potential for industrial contamination and sewage pollution. Currently, the State of São Paulo has registered 4,346 properties as contaminated areas. One such area, Jurubatuba, a neighborhood in the southern city of São Paulo, was found to have contamination by organochlorine solvents and their metabolites in most of its deep wells in 2003. According to a survey done by the State Government, the known contamination covers an area of 6 km by 3.5 km with a magnitude of tens to hundreds of milligrams per litre of organochlorine solvents.
It is essential that governments discipline the use of groundwater in order to ensure quantity and quality of water supplies in the long term. In 2005, the DAEE responded to this threat by enacting Ordinance No. 1594 (October 5, 2005), delimiting an "Area of Temporary Restriction and Control" for groundwater use within 31.57 km². Under this ordinance, the drilling of new wells was prohibited and operation of several wells was restricted. The state environmental agency (CETESB) has classified the area as critical and is working on ways to oversee the management of contaminated sites and groundwater use in the region.
Remediation measures are crucial to prevent further contamination or depletion of water supply. In some cases, relying on the environmental and rehabilitation review processes of local authorities may be too slow to keep up with social and economic demands. To speed up the procedure, the responsibility of assessing risks and defining corrective measures has been transferred to consulting firms, with the methodology and criteria defined by the CETESB.
In the water sector, TÜV SÜD provides technical advisory services for industries, large-scale infrastructure projects, water and waste water treatment plants and networks and desalination facilities. Bureau de Projetos e Consultoria, a company under the TÜV SÜD Group, can also support stakeholders on the subject of groundwater quality.
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