Estimating daily streamflow in the Congo Basin using satellite-derived data and a semi-distributed hydrological model

ABSTRACT

The application of remotely-sensed data for hydrological modeling of the Congo Basin is presented. Satellite-derived data, including TRMM precipitation, are used as inputs to drive the USGS Geospatial Streamflow Model (GeoSFM) to estimate daily river discharge over the basin from 1998 to 2012. Physically-based parameterization was augmented with a spatially-distributed calibration that enables GeoSFM to simulate hydrological processes such as the slowing effect of the Cuvette Centrale. The resulting simulated long-term mean of daily flows and the observed flow at the Kinshasa gauge were comparable (40 631 and 40 638 m³/s respectively), in the 7-year validation period (2004–2010), with no significant bias and a Nash-Sutcliffe model efficiency coefficient of 0.70. Modeled daily flows and aggregated monthly river outflows (compared to historical averages) for additional sites confirm the model reliability in capturing flow timing and seasonality across the basin, but sometimes fails to accurately predict flow magnitude. The results of this model can be useful in research and decision-making contexts and validate the application of satellite-based hydrological models driven for large, data-scarce river systems such as the Congo.     

Contamination des sédiments récents après leur prélèvement

The hydrocarbon content of recent sediments is often very low. Consequently, account must be taken of the numerous possibilities of contamination, which may completely obscure analytical results and, therefore, their interpretation. Two new contaminants are described and their causes determined: (1) hydrocarbons, essentially even-numbered $\text{n-}\text{alkanes}$, from the polyethylene core sleeves of Kullenberg corers, (2) $\text{n-}\text{heptadecane}$, biosynthesized during the storage of wet sediments at 4°C, in darkness.In order to avoid these contaminants, it is advisable to core without plastic core sleeves, and to store the freeze-dried sediments in metal or glassware, under an inert atmosphere. Some of the conclusions of previously published works about hydrocarbons in recent sediments should be re-evaluated.     

Petrology and geochemistry of REE-rich Mafé banded iron formations (Bafia group,Cameroon)

Archaean–Paleoproterozoic foliated amphibole-gneisses and migmatites interstratified with amphibolites, pyroxeno-amphibolites and REE-rich banded-iron formations outcrop at Mafé, Ndikinimeki area. The foliation is nearly vertical due to tight folds. Flat-lying quartz-rich mica schists and quartzites, likely of Pan-African age, partly cover the formations. Among the Mafé BIFs, the oxide BIF facies shows white layers of quartz and black layers of magnetite and accessory hematite, whereas the silicate BIF facies is made up of thin discontinuous quartz layers alternating with larger garnet (almandine–spessartine) + chamosite + ilmenite ± Fe-talc layers. REE-rich oxide BIFs compositions are close to the East Pacific Rise (EPR) hydrothermal deposit; silicate BIFs plot midway between EPR and the associated amphibolite, accounting for a contamination by volcanic materials, in addition to the hydrothermal influence during their oceanic deposition. The association of an oceanic setting with alkaline and tholeiitic magmatism is typical of the Algoma-type BIF deposit. The REE-rich BIFs indices recorded at Mafé are interpreted as resulting from an Archaean–Paleoproterozoic mineralization.     

Austerity urbanism and the promise of immigrant- and refugee-centered urban revitalization in the US Rust Belt

Recent urban studies research emphasizes the unevenness of local responses to immigration in the United States and the emergence of economic development-focused inclusionary initiatives as a response to neoliberal downscaling in the Rust Belt. Scholars also highlight the impact of austerity urbanism – the deepening of neoliberal urbanism – in Rust Belt cities following the 2007–2008 financial crisis, noting its potential to produce progressive activism. This article considers the relationship between downscaling, austerity urbanism, and immigration activism in the Rust Belt by analyzing economic revitalization narratives within a regional consortium of inclusionary initiatives. My findings underscore the incongruities and compromises encompassed by welcoming coalitions operating in the age of austerity. Some local actors are motivated by growth agendas but affirm inclusionary values toward immigrants and refugees to substantiate them. Other actors are motivated by social justice agendas but cite the economic benefits of immigration to garner support from other factions.     

Extension et sédimentation au paléozoïque terminal et au Mésozoïque dans le bassin de Majunga (Nord-Ouest de Madagascar)

The Majunga Basin is located in the northwestern part of Madagascar with a N45–60°E trending axis. It was filled by almost exclusively continental Karoo Supergroup sediments, which are Permian to Early Jurassic in age, and by younger sequences, mainly marine, that were deposited from the Middle Jurassic to the present.The Karoo Basin geometry is deduced from the analysis of seismic sections. A central northeast trending horst is flanked by two sub-basins. Deposition of the Karoo sequences was controlled by these northeast trending faults. On the contrary, the Middle Jurassic to present sequences witness only a slight tilting of the basement towards the northwest.The development of the Majunga Basin includes, therefore, two successive stages. In the synrift episode, from Permian to Early Jurassic times, the sedimentation was syntectonic, controlled by synsedimentary faulting and the creation of a horst and graben extensive pattern. The postrift episode started during the Middle Jurassic.These two stages of the Majunga Basin development correspond to the geodynamic evolution recorded elsewhere in this part of the Gondwana.