Search

A coincidence in the timing of floods and their drivers can be used as a proxy for the causality of flood generation. Here, we investigate the relationship between the seasonality of floods, maximum annual rainfall, and maximum annual soil moisture data of 886 basins in Brazil for 1980–2015 to shed light on process controls of flood generation. Floods tend to occur at the same time of year as soil moisture peaks and lag behind rainfall peaks by 3 weeks. In Amazonia, central and northern Brazil, flood timing is more correlated with the timing of soil moisture peaks than with that of rainfall peaks, which is interpreted as resulting from high subsurface water storage capacities. In southern and southeastern Brazil, on the other hand, flood timing is highly correlated with both soil moisture and rainfall because of low subsurface water storage capacities. These findings can support flood forecasting and climate impact studies. Plain Language Summary: In warm regions, floods are usually generated by a combination of intense rainfall and wet soils. In this paper, we analyze the average timing within the year of floods, extreme rainfall, and soil moisture to elucidate how floods come about in the main Brazilian rivers. We find that in some regions, such as Amazonia and central Brazil, floods tend to occur when soils are wet. In other regions, such as southern Brazil, floods tend to occur when rainfall is most extreme. We believe that these differences are related to differences in the soil water storage capacity. The understanding of the regional importance of each of these components helps increase the efficiency of flood prevention measures and climate change adaptation. Key Points: Flood peaks tend to occur at the same time of year as annual soil moisture peaks and lag behind annual rainfall peaks by 3 weeksFlood seasonality is linked mainly with soil moisture peaks in Amazonia and central Brazil, where soil storage capacity is highFlood timing is highly correlated with rainfall and soil moisture peaks in the south and southeast, where soil storage capacity is low [ABSTRACT FROM AUTHOR]

Disasters worldwide tend to affect the poorest more severely and increase inequality. Brazil is one of the countries with high income‐inequality rates and has unplanned urbanization issues and an extensive disaster risk profile with little knowledge on how those disasters affect people's welfare. Thus, disasters often hit the poorest hardest, increasing the country's income inequality and poverty rates. This study proposes a method to assess the impact of floods on households spatially based on their income levels by conducting flood analysis and income analysis. The method is applied to the Itapocu River basin (IRB) located in Santa Catarina State, Brazil. The flood is assessed by conducting rainfall analysis and hydrological simulation and generating flood inundation maps. The income is evaluated using downloaded 2010 census data and a dasymetric approach. Flood and income information is combined to analyze flood‐impacted households by income level and flood return period. The results confirm the initial assumption that flood events in the IRB are more likely to affect the lowest‐income households rather than the highest‐income levels, thus, increasing the income inequality. [ABSTRACT FROM AUTHOR]

Aim: Flooded forests are critically important for supplying water‐related ecosystem services, but their restoration has been severely limited by low seedling performance due to flooding stress. We classified the flooding tolerance of 15 native tree species in a nursery‐based method to guide species selection for restoring a flooded forest. Location: Atlantic Forest, São Paulo State, Brazil. Methods: We first exposed 15 native tree species typical of flooded forests to four flooding conditions (i.e., normoxia and three increasing hypoxia levels): no flooding, up to the middle of the root system, up to the root collar, and 2 cm above the root collar. After nine months, we evaluated seedling survival, growth (height and stem diameter), and the occurrence of hypertrophied lenticels and adventitious roots. Seedling survival and growth data were combined to create a flooding tolerance index. Further, we planted the same species in two degraded swampy areas under three soil preparation methods: planting seedlings in regular planting holes, on mounds, and in between furrows. We assessed seedling survival and stem diameter of these seedlings after one year. Results: Flooding tolerance index was significantly correlated to the occurrence of hypertrophied lenticels, but not of adventitious roots. Classifying flooding tolerance of tree species was effective in predicting species growth, but not seedling survival, in restoration plantations. Overall, seedling performance in restoration plantations was highly influenced by species identity, but not by soil preparation methods. Conclusions: Species selection to improve restoration performance of flooded forests can be guided by simple and fast screenings performed in nurseries before planting. Pioneer trees may facilitate the establishment of species less tolerant to flooding by reducing water saturation of superficial soil layers and enhancing micro‐relief heterogeneity by litter deposition. Only a few native species should initially be used in the restoration of flooded forests with high water tables. [ABSTRACT FROM AUTHOR]

Using data from the Damage Assessment Reports from the Civil Defence, the current study investigates the relationship between the damage caused by natural disasters and local development at the municipality level in Ceará state, Brazil. The results show that a better urban and water supply infrastructure, a lower population density, and a higher proportion of own revenues relative to total revenues are associated with smaller disaster damage. However, economic development in terms of GDP per capita exhibits a convex relationship with the impact of natural disasters across municipalities, reflecting the potential decreasing returns of preventive investments due to the highly hazardous environment that involves municipalities. [ABSTRACT FROM AUTHOR]

Objective. Income inequality scholars suggest that extreme income inequality leads to spatial segregation, political power concentrated in the high-income (elite) class, and thus, uneven public resource access. This work argues that income inequality may also predict higher levels of vulnerability of urban municipalities to climate-related hazards. Method. Using factor analysis and multilevel regression models, this research tests whether income inequality is a predictor of vulnerability to flood hazards. Results. The analysis shows that income inequality significantly predicts higher levels of a key component of vulnerability in urban Brazilian municipalities. Conclusion. By providing empirical evidence for the theorized linkages between income inequality, spatial segregation, and uneven public resource access, this work bolsters the claims of income inequality scholars who suggest high levels of income inequality have negative social consequences. Additionally, this work is relevant to climate change vulnerability scholars as it underscores the importance of considering income inequality as part of urban climate change vulnerability assessments. [ABSTRACT FROM AUTHOR]

We investigated the response of ant species to landscape and geomorphologic parameters of a long-term (7–11 years) restoration project in the Jequitinhonha River (Northern State of Minas Gerais, Brazil) margins, previously dredged by a diamond mining company. Geomorphological changes from the dredging were severe and the area is unlikely to be adequately restored, mainly due to the negative effects of flooding. Our hypothesis is that ant species assemblages bioindicate successional stages and soil characteristics. We studied the association of effects from the river's flooding zone, the native vegetation, and sedimentary grain size with that of ant species diversity, abundance, and composition. An ant sampling program was conducted in April 2005, using three methods: baits, pitfall traps, and direct collection. Grain size was measured by sieving. In total, 10,784 ants were sampled, belonging to 7 subfamilies, 24 genera and 45 morphospecies. Ant species richness was greater in the undisturbed savanna area than in the restored habitats, and equivalently greater in the ecotone and intermediate zone habitats than on the river bank, the poorest habitat. Atta sexdens rubropilosa indicated a condition related to small forest remnants having well-structured soil. On the other hand, ants with a body length of under 0.5 cm ( Dorymyrmex pyramicus and Pheidole fallax) predominated in sandy areas, where the majority of the granules were the finest. The lack of organic matter and soil structure for constructing suitable nests may prevent large ants from colonizing such areas, and thus inhibit the advance of natural succession. [ABSTRACT FROM AUTHOR]