South America is home to some of the world's most productive and diverse agricultural regions, such as the Pampas and the Chaco plains.
These vast flatlands have been undergoing a rapid transformation in recent decades, as native vegetation and pastures have been replaced by rain-fed croplands, mainly soybean and maize.
This change has been driven by soaring international demand and economic incentives, resulting in an agricultural expansion of 2.1 million hectares per year.
However, this large-scale land use change has also brought significant environmental and social consequences, such as biodiversity loss, soil degradation, greenhouse gas emissions, and displacement of rural communities.
One of the most striking impacts is the increased risk and frequency of surface flooding, which affects millions of people and causes economic losses, infrastructure damage, and health problems.
How agriculture affects the water cycle and flooding
STR/AFP via Getty Images)
A new study, published in Science, reveals how expanding large-scale agriculture is escalating flooding in the largest South American breadbasket, as per Phys.org.
The study, conducted by an international team of researchers from Argentina and the UK, used satellite imagery, field observations, statistical modeling, and hydrological simulations to analyze the trends and mechanisms of groundwater and flooding across the Pampas and Chaco plains over the last four decades.
It found that the replacement of deep-rooted native vegetation and pastures with shallow-rooted annual crops has altered the water balance of the region, causing the regional water table to rise closer to the surface.
This means that there is less capacity for the land to store water and buffer rainfall events, making flooding more likely and widespread.
The researchers estimated that floods are gradually doubling their coverage and becoming more sensitive to changes in precipitation.
They also observed that fine-resolution remote sensing imagery captured the appearance of newly flooded areas, expanding at a rate of approximately 700 square kilometers per year in the central plains.
The study provides unprecedented evidence on how subtle but widespread changes to vegetation cover by human activities can transform the water cycle across large regions.
It also highlights the need for better management and planning of land use and water resources to mitigate the negative effects of agricultural expansion on flooding.
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Implications and recommendations
The findings of the study have important implications for policymakers, farmers, and society at large, as per Mirage News.
The researchers warned that expanding large-scale agriculture is making the South American plains more vulnerable to climate variability and change, which could exacerbate the frequency and intensity of floods in the future.
They also pointed out that floods have significant social and economic costs, such as disrupting transportation, trade, food security, health services, and education.
The researchers suggested that some possible solutions to reduce flood risk include:
Restoring or conserving native vegetation and pastures in strategic areas to enhance water infiltration and storage.
Implementing best management practices for crop production, such as crop rotation, cover crops, no-till farming, contour plowing, terracing, and buffer strips.
Developing early warning systems and flood maps to inform decision making and emergency response.
Promoting adaptive governance and stakeholder participation to balance competing interests and values.
They hope that their study will serve as a "wake-up call" for society to recognize the trade-offs and synergies between agricultural development and environmental sustainability.
They also call for more interdisciplinary research to understand the complex interactions between land use change, water cycle, climate change, and human well-being in South America and beyond.
