In the Amazon, groundwater acts as a reservoir that sustains trees during dry periods. When a drought is prolonged, however, the water levels of underground aquifers drop, exacerbating the drought and leaving forests more vulnerable to fires, especially in years in which the El Ni\u00f1o climate phenomenon occurs.<\/p>\n
These conclusions are part of a study carried out at the University of S\u00e3o Paulo (USP) and published in the journal Science of the Total Environment<\/em> in December, which warned of the need to manage groundwater accumulated between and within rocks.<\/p>\n \u201cWhen the forest has no water to draw from, the smallest spark can start a fire, which then also spreads more easily,\u201d says USP geographer Bruno Conicelli, one of the authors of the article. Using satellite data, he calculated the level of Amazon aquifers between 2004 and 2016 and compared it with data on forest fires. The largest fires occurred in regions where the aquifers were driest.<\/p>\n \u201cBecause aquifers store enormous volumes of water\u2014around 97% of the planet’s fresh water in liquid form\u2014it takes longer for them to replenish, while rivers, which account for 1% of global freshwater reserves, are refilled almost instantly after heavy rain,\u201d explains USP geologist Ricardo Hirata, coauthor of the study.<\/p>\n This phenomenon is most visible in seasonal rivers in arid and semiarid regions, which dry up during the dry season and start flowing again as soon as the rains return. In these places, aquifers are generally deeper than the river surface and even deeper than the riverbeds.<\/p>\n \u201cIn the Amazon, aquifers take months to recover after the rains return,\u201d notes Conicelli. He explains that when there are droughts year after year, as has been the case recently, aquifers are unable to recover. Plants with shallower roots are the first to suffer from a shortage of water.<\/p>\n Variations in the areas affected by fire can be explained both by reduced aquifer levels and exploitation of the forest. There were many fires along the agricultural frontier of Mato Grosso, for example, despite the fact aquifers in the region were not as low. However, there were also intense fires in regions of the Amazon that were drier, such as in the north near the border with Venezuela, in the central region, and at the mouth of the Amazon River. Near the Andes, where it rains more, there were fewer fires.<\/p>\n Losing water The majority of Brazilian rivers are losing water (55%), according to a November study published in Nature Communications<\/em>. In areas of extensively irrigated agriculture, such as the S\u00e3o Francisco River basin, more than 61% of rivers supply water to aquifers.<\/p>\n \u201cThis loss does not mean that most rivers are drying up, but it could become significant in terms of flow if the aquifer level decreases,\u201d explains Edson Wendland, a civil engineer from USP\u2019s S\u00e3o Carlos School of Engineering (EESC) who is supervising the research.<\/p>\n A similar study published in the journal Water <\/em>in 2020 indicated that the main reason behind the reduced flow rates of rivers in the S\u00e3o Francisco basin was a drop in the water level of aquifers supplying the rivers. Water extraction for irrigation was identified as the likely main cause of the problem.<\/p>\n \u201cRivers and aquifers must be managed in conjunction with one another,\u201d argues EESC civil engineer Jos\u00e9 Gescilam Uch\u00f4a, lead author of the Nature Communications <\/em>article. According to Uch\u00f4a, it is important to monitor water resources, especially in areas of irrigated agriculture.<\/p>\n The story above was published with the title “The invisible drought<\/strong>” in issue 347 of january\/2025.<\/p>\n Projects<\/strong> Scientific articles<\/strong>
\n<\/strong>Groundwater surfacing in springs helps maintain perennial rivers that flow all year round, even during dry periods. Some rivers may lose water, however, as it infiltrates the riverbed and returns to aquifers.<\/p>\n
\n1.<\/strong> SACRE: Integrated solutions for resilient cities (n\u00ba 20\/15434-0<\/a>); Grant Mechanism<\/strong> Thematic Project; Principal Investigator<\/strong> Ricardo C\u00e9sar Aoki Hirata (USP); Investment<\/strong> R$6,494,953.26.
\n2.<\/strong> Impact of land use and occupation and climate change on hydrological flows between groundwater and surface water in the outcrops of the Guarani Aquifer system<\/em> (n\u00ba 23\/13160-8<\/a>); Grant Mechanism<\/strong> Doctoral Fellowship; Supervisor<\/strong> Edson Cezar Wendland (USP); Beneficiary<\/strong> Jos\u00e9 Gescilam Sousa Mota Uch\u00f4a; Investment<\/strong> R$365,185.44.
\n3.<\/strong> Extreme precipitation and temperature events in Brazil in the context of climate change:<\/em> Statistical properties and future changes<\/em> (n\u00ba 22\/06017-1<\/a>); Grant Mechanism<\/strong> Doctoral Fellowship; Supervisor<\/strong> Edson Cezar Wendland (USP); Beneficiary <\/strong>Andr\u00e9 Sim\u00f5es Ballarin; Investment<\/strong> R$158,795.17.<\/p>\n
\nLUCAS, M. C. et al<\/em>. Significant baseflow reduction in the Sao Francisco river basin<\/a>. Water<\/strong>. vol. 13, no. 2. dec. 22, 2020.
\nTOLEDO, N. et al<\/em>. Dynamics of meteorological and hydrological drought: The impact of groundwater and El Ni\u00f1o events on forest fires in the Amazon<\/a>. Science of the Total Environment<\/strong>. vol. 954, no. 176612. dec. 2024.
\nUCH\u00d4A, J. G. S. M. et al.<\/em> Widespread potential for streamflow leakage across Brazil<\/a>. Nature Communications<\/strong>. vol. 15, no. 10211. nov. 25, 2024.<\/p>\n","protected":false},"excerpt":{"rendered":"Over-exploitation and climate change are damaging environments that depend on underground water reserves","protected":false},"author":545,"featured_media":556335,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"footnotes":""},"categories":[159],"tags":[209,213,224,228,200],"coauthors":[1498],"class_list":["post-556334","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-science","tag-biology","tag-botany","tag-ecology","tag-engineering","tag-environment"],"acf":[],"_links":{"self":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/556334","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/users\/545"}],"replies":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/comments?post=556334"}],"version-history":[{"count":3,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/556334\/revisions"}],"predecessor-version":[{"id":556351,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/556334\/revisions\/556351"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/media\/556335"}],"wp:attachment":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/media?parent=556334"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/categories?post=556334"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/tags?post=556334"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/coauthors?post=556334"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}