River Basin Brazil Research Articles

Databases and Applications of the Soil and Water Assessment Tool (SWAT) Model in Brazilian River Basins: a Review

Databases and Applications of the Soil and Water Assessment Tool (SWAT) Model in Brazilian River Basins: a Review

Development and evaluation of hydraulic geometry relationships for large Brazilian river basins

ABSTRACT River cross-section characteristics are not available for many regions of the world, and they are generally expressed as hydraulic geometry (HG) relationships. These relationships usually represent average characteristics of a region, which can generate biased estimates in smaller basins. Therefore, to improve the representation of river channel geomorphological characteristics, the objective of this study was to use a large database of river cross-section geometries to refine HG relationships for five river basins in Brazil. HG relationships were developed for the entire basins and for hydraulically homogeneous regions, obtained through a geographical convenience method. The relationship between the coefficients of the geometric relationships and morphoclimatic characteristics was assessed, showing a trend between precipitation and slope and the coefficients of the depth relationships. The estimated bankfull width and depth values were also compared to observed data and global datasets, showing an improvement in estimates with the more refined HG relationships.

Hydrographic basins dictate the genetic structure of the paradoxical frog Pseudis bolbodactyla (Anura: Hylidae) in the rivers of Central Brazil

Abstract Rivers are prominent landscape features, acting as key promoters of diversification among freshwater organisms. Albeit generally considered potential barriers to species movement, they may also facilitate gene flow and structure populations of semiaquatic species (Riverine Thruway Hypothesis, RTH). We evaluated the role of rivers on the processes responsible for current genetic variation in the semiaquatic frog Pseudis bolbodactyla, testing whether each hydrographic basin harbours distinct genetic lineages. We sequenced three markers on 166 samples from 13 localities along the Paraná (PR), Araguaia–Tocantins (AT), and São Francisco (SF) River basins in Brazil. We recovered three populations geographically matching each hydrographic basin. Our results indicate migration among basins, with the best model selected using approximate Bayesian computation, including migration between AT and SF and ancient gene flow from PR to the AT–SF ancestor. Our findings are likely related to the orogenic events in Central Brazil dating to the Late Miocene (5 Mya), when hydrographic basins and the geomorphological features of the Brazilian Shield were formed. This suggests that P. bolbodactyla probably represents a species complex, with each lineage occurring in a distinct hydrographic basin, matching the predictions of the RTH.

A New Species of Creptotrematina (Trematoda: Allocreadiidae) from the Red Minor Tetra, Hyphessobrycon eques (Steindachner, 1882) (Characidae) from Brazil, with Comments on the Genetic Divergence of C. Aguirrepequenoi Jiménez-Guzmán, 1973 across a Wide Geographical Range in Middle America.

Allocreadiids are relatively small digeneans that appear to be restricted to freshwater systems distributed across the world. Allocreadiids are highly diverse in the Americas, particularly in the Neotropical biogeographical region. Their taxonomic history has been rather controversial, with several taxonomic reassessments and the description of new genera and species. We sampled Creptotrematina specimens from a characid collected in the Pardo River, Paranapanema River basin in Brazil, and specimens of C. aguirrepequenoi, from Astyanax spp. in several localities between northern Mexico and Costa Rica. The specimens were studied through integrative approaches using morphological and molecular analyses of the 28S rDNA gene and two different regions of the COI mtDNA gene. We describe a new species of Creptotrematina which is differentiated from other congeners by the overall body size, but in particular by the size and position of the cirrus-sac, distribution of the vitelline follicles, and extension of uterine loops in the posterior end of body. Phylogenetic analyses of the 28S rDNA and COI mtDNA genes placed the new species in a monophyletic clade together with all other sequenced species of Creptotrematina, and as a sister species of C. batalhensis. Genetic divergences between the new species and other Creptotrematina spp. varied from 1.1 to 1.2% for the 28S rDNA and 12.4-14.3% for the COI mtDNA. Phylogenetic analysis based on COI mtDNA showed the isolates of C. aguirrepequenoi grouped in four monophyletic clades representing populations geographically separated along a wide geographical range spanning between northern Mexico and Costa Rica, with an estimated genetic divergence between 3.9% and 8.9%. Our findings based on integrative analyses recognize Creptotrematina saltograndensis n. sp. from a characid collected in the Pardo River, Paranapanema River basin in Brazil and provide validation of the wide geographical distribution of C. aguirrepequenoi across Middle-America parasitizing Astyanax spp.; the genetic divergence of the species through the analysis of two regions of COI mtDNA points towards considering it represent a species complex, although we refrain at the moment on describing a new species, awaiting for further verification using other molecular markers, and obtaining fresh material for a more detailed taxonomic analyses. This study increases the known diversity of allocreadiids and contributes to the understanding of evolutionary relationships, host-parasite relationships, and biogeographic history of the group.

Comparative Analysis between Remote Sensing Burned Area Products in Brazil: A Case Study in an Environmentally Unstable Watershed

Forest fires can profoundly impact the hydrological response of river basins, modifying vegetation characteristics and soil infiltration. This results in a significant increase in surface flow and channel runoff. In response to these effects, many researchers from different areas of earth sciences are committed to determining emergency measures to rehabilitate river basins, intending to restore their functions and minimize damage to soil resources. This study aims to analyze the mapping detection capacity of burned areas in a river basin in Brazil based on images acquired by AMAZÔNIA-1/WFI and the AQ1KM product. The effectiveness of the AMAZÔNIA-1 satellite in this regard is evaluated, given the importance of the subject and the relatively recent introduction of the satellite. The AQ1KM data were used to analyze statistical trends and spatial patterns in the area burned from 2003 to 2023. The U-Net architecture was used for training and classification of the burned area in AMAZÔNIA-1 images. An increasing trend in burned area was observed through the Mann–Kendall test map and Sen’s slope, with the months of the second semester showing a greater occurrence of burned areas. The NIR band was found to be the most sensitive spectral resource for detecting burned areas. The AMAZÔNIA-1 satellite demonstrated superior performance in estimating thematic accuracy, with a correlation of above 0.7 achieved in regression analyses using a 10 km grid cell resolution. The findings of this study have significant implications for the application of Brazilian remote sensing products in ecology, water resources, and river basin management and monitoring applications.

The Future Sustainability of the São Francisco River Basin in Brazil: A Case Study

The viewpoint and reaction of a country towards climate change are shaped by its political, cultural, and scientific backgrounds, in addition to the distinct characteristics of its evolving climate and the anticipated and actual consequences of the phenomenon in the times ahead. A region’s climate has a significant impact on how water is managed and used, mostly in the primary sector, and both the distribution of ecosystem types and the amount and spreading of species on Earth. As a result, the environment and agricultural practices are affected by climate, so evaluating both distribution and evolution is extremely pertinent. Towards this aim, the climate distribution and evolution in the São Francisco River basin (SFRB) is assessed in three periods (1970–2000, 1981–2022) in the past and 2041–2060 in the future from an ensemble of GCMs under two SSPs (Shared Socioeconomic Pathways), SSP2-4.5 and SSP5-8.5. The Köppen-Geiger (KG) climate classification system is analyzed, and climate change impacts are inferred for this watershed located in central-eastern Brazil, covering an area equivalent to 8% of the country. Results predict the disappearance of the hot summer (Csa) and warm summer (Csb) Mediterranean climates, and a reduction/increase in the tropical savanna with dry winter (Aw)/dry summer (As). A striking increase in the semi-arid hot (BSh-steppe) climate is predicted with a higher percentage (10%) under SSP5-8.5. The source and the mouth of SFRB are projected to endure the major impacts of climate change that are followed by a predicted increase/decrease in temperature/precipitation. Future freshwater resource availability and quality for human use will all be impacted. Consequences on ecosystems, agricultural, and socioeconomic sectors within the SFRB might deepen the current contrasts between regions, urban and rural areas, and even between population groups, thus translating, to a greater extent, the inequality that still characterizes Brazilian society. Maps depicting land use and cover changes in SFRB from 1985 to 2022 highlight tendencies such as urbanization, agricultural expansion, deforestation, and changes in shrubland and water bodies. Urban areas fluctuated slightly, while cropland significantly increased from 33.57% to 45.45% and forest areas decreased from 3.88% to 3.50%. Socioeconomic data reveals disparities among municipalities: 74.46% with medium Human Development Index (HDI), 0.59% with very high HDI, and 9.11% with low HDI. Most municipalities have a Gross Domestic Product (GDP) per capita below US$6000. Population distribution maps show a predominance of small to medium-sized urban and rural communities, reflecting the basin’s dispersed demographic and economic profile. To achieve sustainable adaptation and mitigation of climate change impacts in SFRB, it is imperative that integrated measures be conducted with the cooperation of stakeholders, the local population, and decision-makers.

Habitat quality on the edge of anthropogenic pressures: Predicting the impact of land use changes in the Brazilian Upper Paraguay river Basin

Landscape changes driven by anthropogenic activities often have negative impacts on ecosystems, jeopardizing the provision of vital services that sustain biotic elements and wildlife. Predicting the effects of such transformations is crucial for developing strategies to mitigate ecological damage. This study explores the interaction of land use changes and habitat quality estimates in the Upper Paraguay River Basin in Brazil, using the InVEST Habitat Quality model to estimate spatiotemporal landscape trends and evaluate the potential impact of land use policies for the future. Under a business-as-usual scenario by 2050, potential land use changes are simulated for shaping habitat quality, habitat degradation, and habitat rarity estimates as landscape proxies for biodiversity conservation. Results show an extensive expansion of pastures through deforestation, leading to progressive habitat degradation with a significant decay in the predicted and observed habitat quality. The habitat quality index estimates show a spatial decrease from 0.78 to 0.57 for the 1989–2050 period. The same trend is observed in protected areas for the period 2019–2050, with an increase of anthropogenic land use and a decrease of the habitat quality from 0.80 to 0.57 in conservation units, and from 0.75 to 0.53 in indigenous lands. For improved conservation outcomes, this work introduces new insights for shaping environmental actions that can be flagged as sustainable land management practices and ecological perspectives towards spatial pressures at different scales. Therefore, government institutions responsible for the protection of conservation units and indigenous communities can be informed about potential land use impacts on their territories. The findings suggest that incorporating additional scenario trends and climate-related variables could be a valuable direction for future studies to extend further the modelling approaches explored in this work.

Hydropower Plants and Ichthyofauna in the Tocantins–Araguaia River Basin: Challenges for Planning and Approaches to Ichthyofauna Conservation

The management of water resources is a complex issue, and the conservation of fish and fishery resources is a growing challenge given the increase in the number of hydroelectric projects in Brazilian river basins. This study describes the fragmentation of the Tocantins–Araguaia River Basin resulting from the installation of hydroelectric plants in operation and planned by the electricity sector until 2050, as well as its relationship with the conservation of fish fauna, especially long-distance migratory species. The hydroelectric projects in operation and planned were analyzed using data obtained from the National Electric Energy Agency. A literature review was carried out to assess the fish species of the Tocantins–Araguaia ecoregion, with an emphasis on long-distance migrants. In general, 75 hydroelectric dams are in operation, and a further 119 projects are in the electricity sector’s plans for construction by 2050 in the Tocantins–Araguaia ecoregion, including a stretch of the basin above the Tucurui dam, which will accentuate the fragmentation in the area. Of the 702 species found in the region, 31.1% are endemic, 6.1% are endangered, and several long-distance migratory species have had their populations restricted. Analysis of this information highlights the widespread impact on the ichthyofauna, affecting both species with a restricted distribution and migratory species with a long-distance distribution. The studies associated with the projects contribute to the advancement of knowledge, but they are only carried out after the works have been defined, which makes it difficult to plan conservation in advance. Transformations in the basin are imminent given the current changes and those expected in the coming years because of the electricity sector’s planning for the region. Considering the inseparable relationship between biodiversity and socio-environmental and cultural diversity, fish conservation is intrinsically linked to the conservation of socio-diversity and the effective participation of local communities from the start of the process. Fish depend on water, and people need both water and aquatic diversity. In conclusion, a well-structured and adaptative conservation plan, combined with the integration of effective fish routes, can contribute to the sustainable development of hydroelectric projects while safeguarding the biodiversity and ecological integrity of the Tocantins–Araguaia Basin.

Osteoporosis and Bone Deformities in Free-Living Geoffroy's Toadhead Turtles (Phrynops geoffroanus) Rescued from Urban Areas in the Metropolitan Region of Recife (Pernambuco, Brazil)

Abstract Organic pollutants have bioaccumulative effects and induce a high index of toxicity in aquatic ecosystems. The aim of our study was to report tomographic abnormalities found in free-living turtles (Geoffroy`s toadhead turtle, Phrynops geoffroanus) from an urban area near the Capibaribe and Beberibe river basins in Brazil, which are known to be contaminated by heavy metals as well solid waste. Clinical and tomographic evaluation of eight turtles was performed to assess their health status for subsequent release. Tomographic analysis revealed bone abnormalities including demineralization, coarse trabecular pattern, subperiosteal bone resorption, deformity of dorsal vertebrae and shell fracture. Considering that turtles are recognized as bioindicators of water quality, a high occurrence of bone abnormalities may suggest an association with environmental pollution in the studied area and signal that conservation initiatives are needed to safeguard the aquatic ecosystem of the metropolitan region of Recife.

Hidden Diversity in Eigenmannia (Gymnotiformes: Sternopygidae) Populations from Upper Paraná and Paraguay Rivers.

Eigenmannia is a highly diverse genus within the Sternopygidae family, comprising 30 species. Due to its complex taxonomy, molecular analyses have been crucial for species delimitation within this group. Therefore, the present study presents a genetic analysis using sequences of the mitochondrial gene cytochrome c oxidase subunit 1 (COI) in specimens previously identified through alpha taxonomy as E. correntes (with unpublished data), E. virescens, and E. trilineata, originating from various locations within the Upper Paraná and Paraguay River basins in Brazil. The molecular data confirm the taxonomic complexity of the genus, as individuals morphologically identified as E. virescens and E. trilineata shared the same haplotype (H52). Furthermore, the results of the species delimitation tests suggest that specimens morphologically identified as E. virescens belong to the species E. trilineata. In addition, samples morphologically identified as E. correntes may correspond to more than one Operational Taxonomic Units (OTUs). Furthermore, the intraspecific Kimura-2-parameter (K2P) distances within the different studied populations are significant. This study has contributed valuable information about genetic diversity in Eigenmannia, emphasizing the importance of using integrative analyses to resolve taxonomic conflicts within the group. It also supports biogeographical studies and assists in biodiversity conservation efforts.

Fishes of the upper rio Paraná basin: diversity, biogeography and conservation

Abstract The upper rio Paraná basin drains the most developed and environmentally degraded region in South America: the Brazilian southeast. While it is one of the most well-known Neotropical fish assemblages, it is also one of the most threatened by anthropic activity. Urbanization, deforestation, dam construction, invasive species, and water pollution not only reduce the living area of species but also alter our perception of the basin and its biotic elements. Such changes are so profound and pervasive that raise uncertainties about the native or non-native status of several species. This paper aims to offer a detailed picture of the native diversity and historical biogeography of the fishes in the upper rio Paraná basin, which we hope will offer a solid foundation for future conservation policies. We update the list of native species, analyze geographical distributions, and identify biogeographical patterns, emphasizing areas requiring recognition as distinct biotas for conservation efforts. Over the past 15 years, more than 100 additional species have been described or recorded, expanding the total to 341 native species belonging to six orders and 30 families, making it the richest river basin in Brazil outside the Amazonian region. Unlike most neotropical basins where Characidae dominates, loricariids make up nearly one-fourth of the total fish diversity in the region. Species and clades concentrate in the central basin, while endemics are confined to peripheral areas due to the complex biogeographical history shared with neighboring basins. Eighteen distinct biogeographical regions are identified, discussing their composition, histories, and conservation implications. The upper rio Paraná basin has 10% of its fish fauna ranked as endangered and present 128 non-native species, including three hybrids. This places it as the major drainage with the largest number of endangered taxa in the neotropics and at the same time the one with the most numerous non-native elements. Existing protected areas are deemed ineffective in preserving diverse assemblages and fail to safeguard the majority of threatened and narrowly-endemic species.

Orientatractis bowseri n. sp. (Nematoda: Cosmocercoidea: Atractidae) parasite of Peltocephalus dumerilianus (Schweigger) (Testudines: Podocnemididae) from the Brazilian Amazon.

Peltocephalus dumerilianus (Schweigger) is a diurnal freshwater turtle widely distributed in the Orinoco and Amazon River basins in Brazil, Colombia, Peru, Ecuador, Venezuela, and French Guiana. During a helminthological survey of freshwater turtles from the Brazilian Amazon, numerous nematodes with characteristics of the genus Orientatractis Petter, 1966 were recovered from the stomach of Peltocephalus dumerilianus. These nematodes were different from all congeneric species, and we describe herein. Orientatractis bowseri n. sp. differs from all known species of the genus by having dorsal cuticular projections on the posterior region of the females, distribution of caudal papillae and by having papilla-like ornamentations on the cuticle distributed from the mid-esophagus to the mid portion of the body. This study represents the fourth specie of the genus Orientatractis reported in Brazil, the seventh species of Orientatractis in the Neotropical region, and the third found infecting freshwater turtles in Brazil.

Genetic Diversity in Natural Populations of the Near-Threatened Species Lignobrycon myersi (Characiformes, Triportheidae): Implications for Species Conservation.

The river basins of Brazil contain a highly diverse ichthyofauna of remarkable endemism, including several threatened species. Accordingly, Lignobrycon myersi is a fish species distributed only in a few rivers from the state of Bahia, northeastern Brazil. Since this species is classified as Near Threatened and is poorly studied, efforts to understand the genetic structure of populations and putative cryptic forms should help define efficient strategies of management and conservation. Herein, the molecular identification and the population genetic diversity of specimens of L. myersi across their range (Almada, Contas, and Cachoeira river basins) were assessed using mitochondrial markers (16S rDNA and D-Loop, respectively). The inferences based on phylogenetics, genetic distance, and species delimitation methods invariably identified all samples as L. myersi. In addition, sequencing of D-loop fragments revealed significant haplotype diversity and a considerable level of population genetic structure. Despite their geographic isolation, these data suggested that populations from Almada and Contas rivers represent a single evolutionary lineage that could be managed as a whole. In contrast, the population from Cachoeira River was highly differentiated from the others and should be managed separately as a unique and endemic unit, particularly focused on the conservation of native habitats.

WRF-Hydro for Streamflow Simulation in the MATOPIBA Region within the Tocantins/Araguaia River Basin—Brazil: Implications for Water Resource Management

The effective management of water resources in regions with a high potential for water resources, such as the Tocantins/Araguaia Basin in Brazil, is crucial in the face of current climate change and urban and agricultural expansion. In this context, this study evaluates the WRF-Hydro hydrological model to simulate the flow of the Manuel Alves Pequeno, Vermelho, and Manuel Alves Grande rivers in the MATOPIBA region (encompassing areas from the states of Maranhão, Tocantins, Piauí, and Bahia), an agricultural frontier and the most key area in terms of grain production in Brazil. The aim is to analyze the hydrological parameters of soil infiltration, surface retention depth, land surface roughness, and Manning’s channel roughness. The simulations are conducted at a spatial resolution of 3 km with a channel network of 100 m, covering a period of heavy rainfall from 13 March to 1 June 2018. For model validation, observational data from three river gauge stations of the National Water and Sanitation Agency are used, with assessments based on the Nash-Sutcliffe efficiency index, standard deviation of observations, root mean square error, percentage bias, and correlation coefficient, resulting in values of 0.69, 0.56, 4.99, and 0.83, respectively. In particular, the adjustment of the infiltration factor and surface roughness parameter has a greater contribution to improving the statistical results than the adjustment of the other two hydrological parameters. Additionally, the quality of discharge simulation at each river gauge station is correlated with the temporal distribution of simulated precipitation compared to observed data in the drainage network. Highlighting WRF-Hydro’s potential as a fine-scale model easily coupled with numerical weather prediction, this study significantly advances regional river dynamics evaluation, crucial for strategic water resource management.

Mercury and CO2 emissions from artisanal gold mining in Brazilian Amazon rainforest

AbstractThe Tapajós River basin in Brazil is one of the world’s regions most affected by artisanal gold mining (ASGM), which is responsible for the release of mercury and high energy consumption. Mercury, mixed with gold-containing materials and then released through heating to extract the gold, can be recovered using a simple distillation device called a retort. Use of these tools has now become standard. In a comprehensive study, we investigated the use of mercury and energy at 47 mining sites in the Tapajós River basin. These included numerous mines that were operated informally or in some cases even illegally and are therefore not accessible to outsiders. Our survey shows that 1.7 kg of mercury are used per kg of gold extracted, of which only about 0.19 kg of mercury is released into the environment when retorts are used. Overall, this means an annual release of at least ≈2.5 tonnes of mercury in the region, even when retorts are used. We also find that ASGM contributes to climate change through energy consumption responsible for the release of about 16,000 kg of CO2 equivalent per kilogram of gold. This means that even artisanal gold mining, which uses retorts, has a major environmental impact.

Environmental vulnerability assessment of the Doce River basin, southeastern Brazil.

Environmental vulnerability is an important tool to understand the natural and anthropogenic impacts associated with the susceptibility to environmental damage. This study aims to assess the environmental vulnerability of the Doce River basin in Brazil through Multicriteria Decision Analysis based on Geographic Information Systems (GIS-MCDA). Natural factors (slope, elevation, relief dissection, rainfall, pedology, and geology) and anthropogenic factors (distance from urban centers, roads, mining dams, and land use) were used to determine the environmental vulnerability index (EVI). The EVI was classified into five classes, identifying associated land uses. Vulnerability was verified in water resource management units (UGRHs) and municipalities using hot spot analysis. The study employed the water quality index (WQI) to assess the EVI and global sensitivity analysis (GSA) to evaluate the model input parameters that most influence the basin's environmental vulnerability. The results showed that the regions near the middle Doce River were considered environmentally more vulnerable, especially the UGRHs Guandu, Manhuaçu, and Caratinga; and 35.9% of the basin has high and very high vulnerabilities. Hot spot analysis identified regions with low EVI values (cold spot) in the north and northwest, while areas with high values (hot spot) were concentrated mainly in the middle Doce region. Water monitoring stations with the worst WQI values were found in the most environmentally vulnerable areas. The GSA determined that land use and slope were the primary factors influencing the model's response. The results of this study provide valuable information for supporting environmental planning in the Doce River basin.

Hidden diversity and evolutionary diversification in Phalloceros harpagos Lucinda (Cyprinodontiformes: Poeciliidae)

AbstractThe distribution of Phalloceros species is generally allopatric and restricted; however, Phalloceros harpagos has a wide distribution and exhibits morphological variation among populations from different Brazilian river basins. Different species delimitation tests using cytochrome C oxidase subunit I gene sequences indicated that P. harpagos is a species complex that comprises between 7 and 9 phylogroups. The separation of the Paraná and Paraíba do Sul River basins most likely caused the diversification of these phylogroups in the Miocene period. The majority of phylogroups have a narrow distribution; however, one phylogroup has a broad distribution, being found primarily in the Paraná, Ribeira de Iguape, and Iguaçu River basins. This distribution can be attributed to possible headwater capture events caused by the reactivation of faults and erosion in the quaternary. Estimates about the times of divergence based on molecular data could be used to infer the biogeographic processes related to the diversification of South American freshwater fish.

Molecular phylogeny of two Rhinoxenus species (Monogenea: Dactylogyridae) from the nasal cavities of serrasalmids (Characiformes: Serrasalmidae) from Brazil.

The dactylogyrid genus Rhinoxenus (Monogenea: Dactylogyridae) is composed of specialized monogeneans infecting the nasal cavities of freshwater fishes from the Neotropical region. This taxon currently comprises 11 species and is easily distinguished from other monogeneans by the absence of the dorsal bar, ventral anchor with inconspicuous roots covered by a sclerotized cap, dorsal anchor greatly modified into a needle-like shape, and hook pair 2 located into bilateral lobes of the trunk. Specimens of Rhinoxenus euryxenus and Rhinoxenus paranaensis were found infecting the nasal cavities of Serrasalmus marginatus and Serrasalmus maculatus, respectively, from the Paraná River basin in Brazil. For the first time, molecular data of Rhinoxenus spp. were obtained and used as a basis for phylogenetic analyses of the genus. Furthermore, our findings represent the first record of R. paranaensis in Brazil.

Socio-Environmental Vulnerability to Drought Conditions and Land Degradation: An Assessment in Two Northeastern Brazilian River Basins

Over the past few decades, a significant amount of agricultural land has been lost due to soil degradation/desertification. In addition, the increasing frequency of extreme events, such as intense droughts and forest fires, has negatively impacted various ecosystem services. Two of the main Brazilian biomes—the Cerrado and the Caatinga—have been affected by increased rainfall variability, leading to desertification, increased fire frequency, and, consequently, rising concerns regarding the water and food security of the local population. In this study, we develop a methodology to assess these impacts using a Socio-Environmental Vulnerability Index (SEVI) that combines physical, environmental, and socio-economic indicators related to exposure, sensitivity, and adaptation, as well as including socio-environmental feedback. The developed SEVI is then applied to the São Francisco and Parnaíba river basins. The proposed index is based on the MEDALUS methodology and is adapted to include multiple biological, physical, and socio-economic indicators, allowing for the discrimination of areas characterized by different levels of vulnerability. We also analyze the effectiveness of governmental policies, such as the creation of conservation areas and the rural registration of properties, in reducing vulnerability. The SEVI analysis highlights that adaptive capacity is the main constraint for reducing socio-environmental vulnerability in the Parnaíba basin, while exposure and sensitivity are the greater challenges in the São Francisco basin. The results of this study are crucial for the prioritization of recovery actions in degraded areas.

Spatial–Temporal Variability of Climatic Water Balance in the Brazilian Savannah Region River Basins

The evaluation of water and energy cycles from the estimation of water balance is a fundamental instrument to assess the water potential of a region. Thus, the objective of this study was to evaluate the probable monthly water deficit and surplus in Cerrado river basins and the trend of monthly data on climatic water balance (CWB) and its input variables in the study region. Monthly data on precipitation (P) and reference evapotranspiration (ETo) from January 2003 to December 2019 were used. The deficit and the probable monthly water surplus were obtained from the CWB for each of the 4531 ottobasins. For this, the frequency equal to or greater than 80% of permanence in time was used as a reference. Trend analysis was applied. In the rainy season, most ottobasins showed positive CWB. On the other hand, in the period of lower water availability, most ottobasins showed a negative balance. In all months, there was some ottobasin with a significant trend both for CWB and for P and ETo. In most situations, these trends were a decrease in CWB and monthly P and an increase in monthly ETo.