Groundwater vulnerability assessment in coastal plain of Rio Grande do Sul State,Brazil, using drastic and adsorption capacity of soils

Groundwater vulnerability assessment to delineate areas that are more susceptible to contamination has become an important element for resource management and land use planning. The objective of this work was to integrate hydrogeologic data in a geographic information system (GIS) for phreatic groundwater vulnerability assessment of a pilot area from the Coastal Plain of the Rio Grande do Sul State, Brazil, using the DRASTIC method and adsorption capacity of soils. The studied ions were copper, lead, sulfate and phosphate. Using the original DRASTIC method, the vulnerability presented high values, mainly due to the texture of the sediments and the low depths of waters, which favor the accessibility of the contaminants to the groundwaters. DRASTIC with adsorption capacity of soils showed specifics results for each studied ion. Groundwater vulnerability to metals in relationship to anions was lower. These results show that the original DRASTIC method represents better contaminants with high mobility. An erratum to this article can be found at     

National-scale data-driven rainfall induced landslide susceptibility mapping for China by accounting for incomplete landslide data

China is one of the countries where landslides caused the most fatalities in the last decades.The threat that landslide disasters pose to people might even be greater in the future,due to climate change and the increasing urbanization of mountainous areas.A reliable national-scale rainfall induced landslide suscep-tibility model is therefore of great relevance in order to identify regions more and less prone to landslid-ing as well as to develop suitable risk mitigating strategies.However,relying on imperfect landslide data is inevitable when modelling landslide susceptibility for such a large research area.The purpose of this study is to investigate the influence of incomplete landslide data on national scale statistical landslide susceptibility modeling for China.In this context,it is aimed to explore the benefit of mixed effects mod-elling to counterbalance associated bias propagations.Six influencing factors including lithology,slope,soil moisture index,mean annual precipitation,land use and geological environment regions were selected based on an initial exploratory data analysis.Three sets of influencing variables were designed to represent different solutions to deal with spatially incomplete landslide information:Set 1(disregards the presence of incomplete landslide information),Set 2(excludes factors related to the incompleteness of landslide data),Set 3(accounts for factors related to the incompleteness via random effects).The vari-able sets were then introduced in a generalized additive model(GAM:Set 1 and Set 2)and a generalized additive mixed effect model(GAMM:Set 3)to establish three national-scale statistical landslide suscep-tibility models:models 1,2 and 3.The models were evaluated using the area under the receiver operating characteristics curve(AUROC)given by spatially explicit and non-spatial cross-validation.The spatial pre-diction pattern produced by the models were also investigated.The results show that the landslide inven-tory incompleteness had a substantial impact on the outcomes of the statistical landslide susceptibility models.The cross-validation results provided evidence that the three established models performed well to predict model-independent landslide information with median AUROCs ranging from 0.8 to 0.9.However,although Model 1 reached the highest AUROCs within non-spatial cross-validation(median of 0.9),it was not associated with the most plausible representation of landslide susceptibility.The Model 1 modelling results were inconsistent with geomorphological process knowledge and reflected a large extent the underlying data bias.The Model 2 susceptibility maps provided a less biased picture of landslide susceptibility.However,a lower predicted likelihood of landslide occurrence still existed in areas known to be underrepresented in terms of landslide data(e.g.,the Kuenlun Mountains in the northern Tibetan Plateau).The non-linear mixed-effects model(Model 3)reduced the impact of these biases best by introducing bias-describing variables as random effects.Among the three models,Model 3 was selected as the best national-scale susceptibility model for China as it produced the most plausible portray of rainfall induced landslide susceptibility and the highest spatially explicit predictive perfor-mance(median AUROC of spatial cross validation 0.84)compared to the other two models(median AUROCs of 0.81 and 0.79,respectively).We conclude that ignoring landslide inventory-based incomplete-ness can entail misleading modelling results and that the application of non-linear mixed-effect models can reduce the propagation of such biases into the final results for very large areas.     

Petrology,phase equilibria modelling,noble gas chronology and thermal constraints of the El Pozo L5 meteorite

We present the results of physical properties, petrography, bulk chemistry, mineral compositions, phase relations modelling and Noble gases study of the meteorite El Pozo. The petrography and mineral compositions indicate that the meteorite is an L5 chondrite with a low shock stage of S2-S3. Heterogenous weathering was preferentially along shock structures. Thermobarometric calculations indicate thermal equilibrium conditions between 768?°C and 925?°C at ～4 to 6?kb, which are substantially consistent with the petrological metamorphism type 5. A pseudosection phase diagram is relatively consistent with the mineral assemblage observed and PT conditions calculated. Temperature vs. fO₂ diagram shows that plagioclase compositional stability is very sensitive to Tschermack substitution in orthopyroxene, clinopyroxene and X_An plagioclase during the high temperature metamorphic process. Based on noble gases He, Ne, Ar and K contents a cosmogenic exposure age CRE of 1.9?Myr was calculated. The ²¹Ne would be totally cosmogenic, with no primordial Ne. The ²¹Ne/²²Ne value (0.97) is higher than solar value. According to the cosmogenic Ne content, we argue that El Pozo chondrite originally had a pre-atmospheric mass of 9–10?kg, which would have been produced by a later collision after the recognized collision of the L-chondrite parent body ～470?Ma ago.     

New rurality and the experience of place: the small rural locality of La Niña,Buenos Aires,Argentina

This paper presents a cultural geographic approach for understanding local social processes of territorial re-appropriation taking place in response to non-local forces and interests. This approach is applied to the small rural locality of La Niña, in Buenos Aires Province, Argentina. The small village of La Niña is currently in a locally-led process of recovering from a recent depopulation trend caused mainly by the irruption of transnational agribusiness. As economic opportunities have dwindled in the last decades, more recently local inhabitants and new settlers have set forth diverse strategies aimed at mitigating the effects of depopulation on the social structure. We focus our attention on the way the living experience of place is involved in all these strategies. We contend that despite economic and cultural homogenization caused by globalization, the experience of place is a permanent though ever-changing aspect of social life. Our research was based on archival and hemerographic surveys and ethnographic field techniques, encompassing participatory observation, semistructured and in-depth interviews with social and government leaders and local producers as well as field landscape appraisals.     

Enhanced double-mechanism creep laws for salt rocks

The double-mechanism creep law (DM model) is an empirical creep constitutive model widely employed in Brazilian salt rock mechanics. This model often presents good performance in steady-state creep prediction. However, transient creep is not accounted for, and whenever early creep estimates are important, the contribution of this phase might be meaningful. This work adds value by presenting two alternatives to account for transient creep in the DM model. The first alternative couples the transient function from Sandia’s multi-mechanism deformation model to the DM model steady-state creep rate (EDMT model). The second alternative couples the DM model response to Norton’s power law when the strain rate given by the latter remains lower than the one from the former (EDMP model). These models can be implemented in numerical simulators at small code extensions of the DM model implementations. Applications from previous works by the authors are revisited to validate the formulations based on experimental data. EDMT and EDMP models differ in the formulation of transient creep and, consequently, in the time of transition between the transient and the steady-state phases. Both methods were successful in treating transient creep and in simulating experimental results.     

Scientists' warning on extreme wildfire risks to water supply

2020 is the year of wildfire records. California experienced its three largest fires early in its fire season. The Pantanal, the largest wetland on the planet, burned over 20% of its surface. More than 18 million hectares of forest and bushland burned during the 2019–2020 fire season in Australia, killing 33 people, destroying nearly 2500 homes, and endangering many endemic species. The direct cost of damages is being counted in dozens of billion dollars, but the indirect costs on water-related ecosystem services and benefits could be equally expensive, with impacts lasting for decades. In Australia, the extreme precipitation (“200 mm day −1 in several location”) that interrupted the catastrophic wildfire season triggered a series of watershed effects from headwaters to areas downstream. The increased runoff and erosion from burned areas disrupted water supplies in several locations. These post-fire watershed hazards via source water contamination, flash floods, and mudslides can represent substantial, systemic long-term risks to drinking water production, aquatic life, and socio-economic activity. Scenarios similar to the recent event in Australia are now predicted to unfold in the Western USA. This is a new reality that societies will have to live with as uncharted fire activity, water crises, and widespread human footprint collide all-around of the world. Therefore, we advocate for a more proactive approach to wildfire-watershed risk governance in an effort to advance and protect water security. We also argue that there is no easy solution to reducing this risk and that investments in both green (i.e., natural) and grey (i.e., built) infrastructure will be necessary. Further, we propose strategies to combine modern data analytics with existing tools for use by water and land managers worldwide to leverage several decades worth of data and knowledge on post-fire hydrology.     

Geochemical evidence for melting of carbonated peridotite on Santa Maria Island, Azores

The islands of the Azores archipelago emerge from an oceanic plateau built on lithosphere increasing in age with distance from the Mid-Atlantic Ridge from 10 to 45 Ma. Here, we present the first comprehensive major and trace element and Sr–Nd–Pb isotope data from Santa Maria, the easternmost island of the archipelago, along with published data from the other Azores islands situated much closer to the Mid-Atlantic Ridge axis. We can show that the distinctively more variable and more enriched trace element ratios at Santa Maria combined with a relatively small range in Sr–Nd–Pb isotope ratios are the result of low degrees of partial melting of a common Azores mantle plume source underneath thicker lithosphere. This implies that melt extraction processes and melting dynamics may be able to better preserve the trace element mantle source variability underneath thicker lithosphere. These conclusions may apply widely for oceanic melts erupted on relatively thick lithosphere. In addition, lower Ti/Sm and K/La ratios and SiO₂ contents of Santa Maria lavas imply melting of a carbonated peridotite source. Mixing of variable portions of deep small-degree carbonated peridotite melts and shallow volatile-free garnet peridotite could explain the geochemical variability underneath Santa Maria in agreement with the volatile-rich nature of the Azores mantle source. However, Santa Maria is the Azores island where the CO₂-rich nature of the mantle source is more evident, reflecting a combination of a smaller extent of partial melting and the positioning at the edge of the tilted Azores mantle plume.     

Microbiological composition of native and exotic clams from Tagus estuary: Effect of season and environmental parameters

The influence of seasonal and environmental parameters on the occurrence of bacteria was investigated in two clam species (Venerupis pullastra and Ruditapes philippinarum), water and sediment from the Tagus estuary. Total viable counts (TVC), Escherichia coli, Salmonella spp. and Vibrio spp. were evaluated during one-year. Overall, significant seasonal variations were found in both sampling sites, especially for E. coli and Vibrio spp. levels. In summer, significantly higher Vibrio spp. levels were found in R. philippinarum and sediment samples, but not in V. pullastra clams and water samples. In contrast, significantly higher TVC and E. coli levels were observed in winter months in water and sediment samples. Salmonella spp. was generally isolated when higher levels of E. coli were detected, particularly in R. philippinarum. This study is useful for authorities to develop monitoring strategies for coastal contamination and to estimate human health risks associated with the consumption of bivalves.     

Epidemiological analysis of malaria and its relationships with hydrological variables in four municipalities of the State of Amazonas,Brazil

Abstract

This work comprises a spatial, temporal and statistical analysis of the epidemiology of malaria occurrence in four municipalities of the State of Amazonas, Brazil: Coari, Codajás, Manacapuru and Manaus, for the period 2003–2009. The number of malaria cases, precipitation, water level and temperature data were analysed in this study. The strength of the relationship between these hydrological/meteorological variables and the occurrence of malaria was determined by employing the Spearman rank correlation coefficient. Seasonal peaks of malaria were registered, on average, about 1–2 months before the annual maximum temperature and after the river’s seasonal high-water level. The phenomenon called repiquete (notable variations in the water level) was observed during periods of between 9 and 56 days. The results showed a statistically significant correlation between malaria, temperature, precipitation and water level. Temperature influenced malaria occurrence the least, while rainfall was the most important factor, especially in the municipality of Coari. Water level had an important influence on the records of malarial occurrence in the municipality of Manacapuru.

Editor Z.W. Kundzewicz

Citation Wolfarth, B.R., Filizola, N., Tadei, W.P., and Durieux, L., 2013. Epidemiological analysis of malaria and its relationships with hydrological variables in four municipalities of the State of Amazonas, Brazil. Hydrological Sciences Journal, 58 (7), 1495–1504.     

Influence of Environmental Variables and Fishing Pressure on Bivalve Fisheries in an Inshore Lagoon and Adjacent Nearshore Coastal Area

Climate changes affect marine ecosystems and the survival, growth, reproduction and distribution of species, including those targeted by commercial fisheries. The impact of climate change has been reported for many fish species, but studies focusing on the effects of climate on bivalve resources are lacking. In Portugal, the harvesting of bivalves is an old and artisanal activity, of special importance along the Algarve coast (South of Portugal). This study aims to evaluate the influence of climatic, environmental and fisheries factors on the landings of intertidal coastal lagoon and coastal bivalve species (subtidal nearshore species). The environmental and fisheries parameters considered to affect the landings of bivalves in the eastern Algarve were: fishing effort (number of fishing events), sea surface temperature, North Atlantic Oscillation (NAO) index, upwelling index, wind magnitude and direction and river discharges. Analysis of time series data using min/max autocorrelation factor analysis and dynamic factor analysis showed that, for most species, fishing effort was positively related with landings per unit effort trends in the following year. Lagoon bivalve species (Cerastoderma edule and Ruditapes decussatus) responded to different environmental variables than the coastal bivalve species (Chamelea gallina, Pharus legumen, Donax spp. and Spisula solida). Upwelling index had a significant effect on the lagoon bivalves while the NAO index, wind magnitude and direction, and river discharges only affected the coastal species. This study highlighted the need to adapt fishing effort regimes, while considering the background effects of environmental variability, in order to improve fisheries management.