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Despite their importance to water security and their legal protection, diffuse seeps—which are primarily responsible for the formation of wetlands in Brazil's Cerrado savanna biome—continue to be systematically neglected by public policies, environmental consultants, rural landowners, and regulatory agencies. A group of Brazilian researchers points to the disconnect between technical and legal language as one of the main causes of this institutional invisibility.

Diffuse seeps are areas where groundwater flows continuously and diffusely without forming a single point of exudation (where the liquid "rises"). Rather than emerging in a well-defined location, as occurs in point-specific seeps, these flows are distributed over large areas. This results in waterlogged areas with permanently or seasonally wet soils, even without a visible water table.

The group an article in the journal Perspectives in Ecology and Conservation. "What's lacking for the protection of these areas isn't legislation, but law enforcement," says Alessandra Bassani, the first author of the article.

"The Native Vegetation Protection Law [Law 12,651] provides for the protection of 'seeps,' defined as natural outcrops of the water table, even if they don't form watercourses and even if they aren't permanent. This definition applies directly to non-riparian wetlands—that is, those that aren't located on riverbanks and are present in all Brazilian biomes. The problem is that these areas are rarely recognized as 'diffuse seeps' because seeps and springs are still improperly treated in practice as synonyms," explains Bassani.

"In addition, there's a persistent institutional and technical bias that directs protection only to visible surface waters, such as those associated with riverbanks or point-specific seeps, characterized by a single point of groundwater seepage and the presence of an apparent water surface," he adds.

As a result, ecosystems that should remain untouched have been systematically overlooked on maps, in licenses, and in land use permits, including for deforestation, drainage, and installing center pivots for irrigation. Between 1985 and 2020, more than 580,000 hectares of native vegetation in Cerrado wetlands were lost, 61% of which were converted for agricultural use. Replacing native vegetation with pastures and crops directly interferes with aquifer recharge and river base flow.

According to Bassani, Law 12,651 categorizes all natural outcrops of the water table, including diffuse seeps, as Areas of Permanent Preservation (APPs). These areas have permanently or seasonally saturated soil. This protection extends directly to wetlands, which are essential natural reservoirs that maintain river flow through groundwater.

However, these areas remain unprotected because they are not recognized as seeps. The legal terminology has not been correctly applied in mapping, licensing, and enforcement. Bassani points out that "veredas [palm swamps] are the only rural formations expressly recognized in practice as water APPs, effectively protected based on the presence of buriti palms as an indicator, while all other non-riparian wetlands [that are not directly associated with rivers or streams] remain unprotected."

Initially limited to perennial springs and seeps, protection was extended by the Brazilian Supreme Court (STF) in a Direct Action of Unconstitutionality (ADI 4,903/2019) to include areas surrounding seasonal springs and seeps. The legislation distinguishes between "springs" (point-specific sources with sufficient flow to form watercourses) and "seeps" (groundwater outcrops that do not necessarily form a watercourse).

Most of the Cerrado's wetlands are formed by diffuse seeps—slow water sources that are often invisible to the naked eye and that saturate the soil on a perennial or seasonal basis. However, the term "seeps" is rarely used to describe this type of vegetation formation. This has facilitated non-compliance with the law.

One example is the Rural Environmental Registry (CAR), a government system that monitors land use. It groups springs and seeps into a single category as if they were the same, which weakens the implementation of existing legal protections for wetlands.

In the Cerrado, non-riparian wetlands (wet clean fields, wet dirty fields, palm swamps, and campos de murundu [termite savanna]) perform crucial hydrological functions: they store rainwater and ensure the continuous release of water to river courses, even during periods of severe drought. Seasonal wetlands, whose surfaces dry up during part of the year, are also important as aquifer recharge zones.

"These ecosystems play a central role in the water resilience of river basins, in addition to contributing to carbon stocks and regional biodiversity. The Cerrado is considered the 'water tank of Brazil' because it's home to springs and seeps that form the country's main watersheds, including those that feed the Pantanal and the Amazon," says Rafael Silva Oliveira, a professor at the Institute of Biology at the State University of Campinas (IB-UNICAMP), Bassani's doctoral advisor, and senior author of the article.

The suppression and drainage of diffuse seeps is already having an impact, including water scarcity, reduced flow in waterways, and an interrupted supply to communities and agricultural areas. "Protecting diffuse seeps is crucial to preventing the hydrological collapse of the Cerrado, the Pantanal, and various rivers that form the Amazon basin," Oliveira warns.

In light of this, the article proposes two priority actions. First, the consistent adoption of the terms "seeps" and "diffuse seeps" in research, technical reports, licensing opinions, and management practices is necessary to enforce the law. The second priority action is developing high-resolution maps based on eco-hydrological criteria that differentiate riparian from non-riparian wetlands. Techniques such as remote sensing, the use of piezometers (instruments that measure water pressure), and the identification of hydromorphic soils are already available but are not institutionalized.

The researchers also suggest simple field methods, such as digging 30 centimeters into the soil at the height of the rainy season. The presence of water indicates saturation by the water table. Certain plant species, such as Xyris, Utricularia, and Drosera, also serve as reliable indicators of environments fed by seeps.

In addition to Bassani and Oliveira, both based at UNICAMP, the article included the participation of researchers from the University of Brasília (UnB), the Federal University of Minas Gerais (UFMG), and the Federal University of Santa Catarina (UFSC).

The authors argue that correctly applying Law 12,651 is a decisive step toward ensuring national water and climate security. "The legislation protects areas where the water table rises to the surface, such as diffuse seeps; therefore, any drainage intervention in these areas is illegal, since it aims precisely to eliminate the outcropping of groundwater that characterizes these formations as protected by law. Brazil has a rare opportunity to align science and public policy to protect ecosystems that are essential for water security, already recognized by law but neglected in practice," Bassani concludes.