Making a case for power-sensitive water modelling: a literature review

Models are widely used to research hydrological change and risk. However, the power embedded in the modelling process and outcomes is often concealed by claiming their neutrality. Our review shows that in the scientific literature relatively little attention is given to the influence of models on development processes and outcomes in water governance. At the same time, an emerging body of work offering critical insights into the political implications of hydrological models and a nuanced understanding of their application in context has begun to flourish. Drawing on this work, we call for power-sensitive modelling which includes the following considerations: take a holistic approach to modelling beyond programming and coding; foster accountability; work towards just and equitable water distributions; be transparent about the expectations and choices made; and democratise modelling by giving space to and being mindful of representations of multiple bodies of knowledge and multiple stakeholders and by incorporating marginalised people and nature into the modelling process. Our call should not be understood as a suggestion to do away with modelling altogether, but rather as an invitation to interrogate how quantitative models may help to foster transformative pathways towards more just and equitable water distributions.Volkswagen FoundationPeer Reviewe

Magnetic particle characterization in the Seine river system: Implications for the determination of natural versus anthropogenic input

International audience[1] This study presents an innovative application of well-established environmental magnetic proxy parameters on fluvial sediments, with the aim to trace geological and human-induced processes in the complex Seine river drainage system in northern France. We seek to identify environmental fingerprints of mechanical and chemical weathering processes, the regional distribution of the suspended material, and changes in the balance of natural input versus anthropogenic pollution. In order to reach these goals, we applied a combination of rock magnetic and advanced scanning electron microscopic techniques on a large number of sediment trap samples. Generally, we observe an increase in magnetic concentration coupled with a coarsening in magnetic grain size downstream of the Seine river system. Furthermore, the dominant magnetomineralogy changes from high-coercivity minerals upstream in more rural areas to magnetite-dominated assemblages downstream. Each river (segment) shows its specific trend line depending on regional initial input, weathering conditions, drainage area, and potential pollution sources. One major outcome of this study is the observed significant correlation between anthropogenic antimony-rich iron oxide particles and the magnetic concentration. This shows the potential of magnetic remanence measurements as proxy parameters for specific heavy metal pollution concentrations. Hence, the environmental magnetic study presented herein serves to identify major trends as well as local particularities and leads to quantitative analyses of the contributions of individual tributaries in the Seine river system. Components: 9513 words, 9 figures, 4 tables

Radiochemical data for layers inside a buried manganese nodule from core CH71-09, HARMATTAN campaign of the R/V Jean Charcot on the Romanche trench area (Atlantic ocean)

Radiochemical analyses have been performed on micro-samples extracted from various surface and inside layers of a buried manganese nodule recovered from core CH71-09 at a depth of 10.0 cm. Non manganese oxide parts consisting essentially of the surrounding carbonate sediment inlays have been separated using hydrofluoric acid. After processing the samples have been dissecated at 110 Celsius and prepared as an aliquot from which a part is used for radiometric measurements using Alpha spectrometry and the other part is used for uranium-238 and thorium-232 using co-solvant precipitation

Radiochemical data for layers inside manganese crusts retrieved during the ROMANCHA campaign of the R/V Jean Charcot on the Romanche trench area (Atlantic ocean)

Radiochemical analyses have been performed on micro-samples extracted from various surface and inside layers of manganese crusts covering basalt or volcanic breccia rocks (see, Table Annex7-B). Non manganese oxide parts consisting essentially of the surrounding carbonate sediment inlays have been separated using hydrofluoric acid. After processing the samples have been dissecated at 110 Celsius and prepared as an aliquot from which a part is used for radiometric measurements using Alpha spectrometry and the other part is used for uranium-238 and thorium-232 using co-solvant precipitation

Radiochemical data for sediments of cores CH71-08 and CH71-09, HARMATTAN campaign of the R/V Jean Charcot on the Romanche trench area (Atlantic ocean)

Radiochemical analyses have been performed on 500 mg of each carbonate rich sediment sample (i.d., carbonaceous clay or mud) and 2 g for carbonate devoid samples (i.d., pelagic clay or mud). In the last case the CaCO3 part has been separated using hydrofluoric acid. After processing the samples have been dissecated at 110 Celsius and prepared as an aliquot from which a part is used for radiometric measurements using Alpha spectrometry and the other part is used for uranium-238 and thorium-232 using co-solvant precipitation

Energy dispersive X-Ray analysis (EDAX) of layers inside manganese crusts retrieved by the R/V Jean Charcot on the Romanche trench area (Atlantic ocean)

Energy dispersive X-Ray analysis (EDAX)has been performed on micro-samples extracted from various surface and inside layers of manganese nodules and manganese crusts covering basalt or volcanic breccia rocks. Measurements have been performed on pellets built from the samples reduced to powder. Results are presented as average of about 10 point measurements. Concentrations have been normalized at 100% of total metal oxides

Relationships between the Fe-Mn deposits from the Romanche Trench and its hydrothermal environment

The geological characteristics and Fe-Mn deposits from the North wall of the Romanche trench (Atlantic ocean) were studied in order to investigate possible relationships of these deposits with hydrothermalism. The results indicate diffuse hydrothermal activity in all of the rock samples which may explain the notable mineralogical associations observed, such as talc-dolomite-hematite-serpentine. All rock outcrops were covered with Fe-Mn deposits, but no such deposits were noted on sedimentary platforms. The variations in average chemical composition are very low among the different deposits, with the exception of one peculiar encrustation, explained by a local and short-term anomaly of redox potential. Hence, the phenomenon which produces these deposits is not localized. From this study, we conclude that marine Fe-Mn deposits result from the continuous supply of terrigenous iron and discontinuous supply of manganese, probably hydrothermal in origin. Detrital particles and numerous chemical elements are scavenged during the accretion process itself, whereas some trace elements, among the least soluble (Co, Ti, Th, Ce), are adsorbed on these deposits, independently of the accretion. This explains the inverse variation of the content of these elements versus deposit thickness

Chemical analysis of manganese nodules and crusts from the Romanche trench area (Atlantic ocean)

Manganese nodules and manganese crusts covering basalt or volcanic breccia rocks have been analysed using various methods. Energy dispersive X-Ray analysis (EDAX)was used for the determination of Fe, Mn, Ti, Mg, Al, Si, K, Ca, S. Measurements have been performed on pellets built from the samples reduced to powder. Results are presented as average of about 10 point measurements. Concentrations have been normalized at 100% of total metal oxides. Atomic absorption analysis was performed on the same samples for Ni, Cu, Co and Zn elements

Étude sédimentologique et isotopique des carottes de la basse vallée de l'Aude

Au cours du temps, le lit mineur de la Cesse a tendance à se contracter et le lit majeur à recouvrir le lit mineur antérieur. Ceci signifie, d'une part, un changement de dynamique fluviale (substitution d'un lit majeur à un lit mineur) et, d'autre part, l'apparition d'une tendance à l'accumulation.Les dernières crues de l'Aude n'ont pas eu d'incidence importante sur la morphologie du lit de la rivière aux sites échantillonnés. On peut tout au plus envisager un dépôt décimétrique au site CPS3. Par ailleurs, il apparaît nettement que les retombées de Tchernobyl ont été assez faibles dans cette région