Novel socio-environmental vulnerability index pinpoints sustainability issues in Brazilian river basins

Woman washing clothes in the Parnaíba River near Nazária, Piauí state, Brazil. Credit: Wilson Dias/Agência Brasil
Brazilian researchers have developed a comprehensive index called SEVI (Socio-Environmental Vulnerability) that measures a region’s vulnerability by combining environmental, physical, social, and economic indicators. The researchers applied this index to analyze the basins of the Parnaíba River and São Francisco River in the Northeast of Brazil. The Parnaíba and São Francisco basins are vital for agricultural expansion and biodiversity conservation, as they encompass over 780 municipalities and part of the threatened Caatinga and Cerrado biomes.
The findings of the study revealed that the key obstacles to improving the socio-environmental vulnerability of the Parnaíba basin, the second largest river basin in the Northeast, are infrastructure deficits, income disparities, and inadequate conditions for human development, all of which hinder adaptive capacity. In the São Francisco basin, the most significant causes of vulnerability are population density, soil degradation/desertification, and climate factors such as temperature and precipitation. These research findings were published in the journal Sustainability by authors affiliated with the National Space Research Institute (INPE) and the National Disaster Surveillance and Early Warning Center (CEMADEN).
Biologist Rita Marcia da Silva Pinto Vieira, the first author of the article, emphasized the need to consider the specific characteristics of each region when planning sustainable development projects, as well as the deficiencies of certain public policies. The study addresses an issue that affects agricultural areas worldwide, particularly in developing countries. The integration of socio-economic indicators reinforces the notion that sustainability is influenced not only by climate, environmental factors, and soil degradation but also by human activity and biodiversity.
The SEVI index was developed by combining indicators related to adaptation (human development, infrastructure, and income), sensitivity (days without rain, land use and cover, temperature, and soil type), and exposure (population density and soil degradation or desertification). The methodology was inspired by the environmentally sensitive areas (ESA) approach of the MEDALUS project, conducted in eight European Union countries in the late 1980s and early 1990s. The researchers assigned weightings to the indicators and overall index, ranging from very low to very high.
The study analyzed a total area of approximately 962,000 square kilometers (km²), with a population of around 20 million people, mostly residing in urban areas. Of this population, 16 million live in the São Francisco basin, which spans six states. There are four million people in the Parnaíba basin. According to the SEVI index, 53% of the São Francisco basin exhibits “very high” and “high” vulnerability, encompassing 337,569 km² with fragile socio-environmental conditions, partially overlapping with officially recognized desertification hotspots. In the Parnaíba basin, the proportion is 37% (121,990 km²). A significant portion of the analyzed area (549,830 km²) demonstrates “very low” and “low” adaptive capacity. Exposure is classified as “very high” and “high” in 62.8% and 30.7% of the São Francisco and Parnaíba basins, respectively. Sensitivity to vulnerability is also high in both basins (341,726 km² and 123,666 km²). These results mainly reflect population density, soil degradation, desertification, and the number of days without rain, which directly impacts the risk of wildfires in the dry season.
Climate change is expected to exacerbate these problems. Previous studies using global models have projected a significant decrease in streamflow in the São Francisco and Parnaíba rivers in the coming decades. Furthermore, deforestation rates have increased in the region, posing additional challenges to sustainability.
The researchers also assessed conservation units located in both basins and found that the Parnaíba basin exhibits lower vulnerability compared to the São Francisco basin. However, within a 5 km buffer zone, 32.4% of the São Francisco basin area (12,477 km²) is highly vulnerable, indicating human pressure from deforestation and burning in fully protected areas. Lapa Grande State Park in Minas Gerais stood out as the most well-preserved conservation unit in the region, with low vulnerability in 84.6% of its area.
The authors recommended extending conservation units, implementing sustainable land management practices in adjacent buffer zones, and developing strategies for the protection of ecosystem services and local vegetation. These initiatives should be shared with farmers in the region, particularly those facing high socio-environmental vulnerability and limited resources. By focusing on the specific variables of each region and biome, the SEVI index can be applied to support national climate change adaptation plans and the rehabilitation of degraded areas in other regions around the world.
This research provides valuable insights into the socio-environmental vulnerability of Brazilian river basins and emphasizes the importance of sustainable practices and conservation efforts to mitigate the challenges posed by climate change and human activities.
Citation: Rita Marcia da Silva Pinto Vieira et al, Socio-Environmental Vulnerability to Drought Conditions and Land Degradation: An Assessment in Two Northeastern Brazilian River Basins, Sustainability (2023). DOI: 10.3390/su15108029
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