A global study published in the journal Nature revealed that the sinking of deltas affects more than half of these ecosystems worldwide, including the South American deltas of the Paraná, Amazon, and Magdalena.
The phenomenon, mainly caused by human activities, progresses faster than the rise in sea level.
Scientists from the United States, United Kingdom, Italy, Germany, Canada, and the Netherlands analyzed 40 deltas on five continents.
After this, they discovered that between 54 and 65% of these areas suffer subsidence, that is, the progressive sinking of the ground.
In 19 of the 40 deltas studied, more than 90% of the area exhibits this process. The direct consequence is the reduction in height of the land relative to the sea level.
This increases the risk of flooding, land loss, and damage in productive areas. The deltas support large populations and concentrate key agricultural, fishing, and economic activities.
The situation in South America
The researchers determined that the sinking of deltas in the Paraná, Amazon, and Magdalena shows a moderate level of subsidence. The ground descends at a rate of less than 2 millimeters per year.
The Paraná Delta, which extends through Entre Ríos and Buenos Aires with more than 17,000 square kilometers, is part of the analyzed list.
It is one of the most important wetlands in South America and possesses great biodiversity.
The scientists detected that “the average rate of local subsidence is greater than the regional rate of sea level rise” in this delta.
The report indicates that “the rate of sea level rise is 0.2 millimeters per year” in this region.
The Amazon Delta also shows moderate sinking rates, below 2 millimeters per year. The conditions reflect a lower vulnerability compared to other deltas with extreme subsidence.
The Magdalena River delta in Colombia shows sinking of deltas, although less pronounced than in Amazon and Paraná.
The study noted that “subsidence is also observed, although scientists do not highlight it as an extreme process“.
In all three South American cases, the ground descends faster than the sea level rises, but the figures are far from the critical values of other systems.
Causes and solutions to the sinking of deltas worldwide
Human activities are the factors that most impact the sinking of deltas. The extraction of groundwater and the reduction of sediments lead the causes.
The scientists emphasized the urgency to “regulate the extraction of groundwater and restore the transport of sediments” to reduce the sinking.
They argued that local management can have immediate effects, while climate change adaptation requires long-term actions.
The research identified key factors that worsen the situation:
- Excessive extraction of groundwater
- Reduction of sediment transport
- Intensified human pressures
- Lack of local regulations
The scientists recommended constant monitoring to anticipate changes and avoid future risks.
They highlighted that the situation of the three analyzed deltas in South America, although requiring vigilance, is far from the most severe scenarios observed in Asia or Africa.
Periodic monitoring is presented as a key tool for the management and protection of these regions. The data showed that the relative stability of these deltas could change if human or natural pressures increase.
