Influence of the Mekin hydroelectric dam on the distribution of benthic macroinvertebrates of the Dja stream: South Cameroon region

This work was conducted with the aim of studying the biodiversity of benthic macroinvertebrates in the Dja River and determining the effect of the Mekin hydroelectric dam on their population in relation to the physico-chemical quality of the water. The study ran from May to October 2020 and samplings were carried out on a monthly basis in four different sampling stations located upstream and downstream of the dam. The physico-chemical analyses were done according to standard methods, while the benthic macrofauna was collected using a turbid net of 400 µm mesh size over a total area of about 6 m2 per station. Physico-chemical analyses revealed a decreasing evolution from upstream to downstream of the dam of nitrogen forms (NO3- (1.67mg/L-0.41mg/L); NH4+ (0.31 mg/L-0.21 mg/L) with p>0.05); Electrical Conductivity (21.45µS/Cm-17.1µS/Cm with p<0.05) and Suspended Solids (11.10mg/L-6.57mg/L with p<0.05); while Dissolved Oxygen (49.82%-78.23% with p<0.05) and velocity (0.04m/s-0.23m/s) increased. Organic Pollution Index revealed that the water was moderately polluted (3-4). In total, 1894 individuals, of which 1044 belonging to 2 phyla, 2 classes, 6 orders, 27 families and 47 genera/species were collected upstream; and 850 belonging to 3 phyla, 4 classes, 8 orders, 28 families and 45 genera/species were collected downstream. Odonata was largely abundant and highly represented Trithemis dorsalis (96.05%); while downstream, Heteroptera was largely abundant and highly represented by Poissonia sp1. (79.78%). These results revealed that restoration of the upstream of the dam impacted by organic pollution and physical degradation of the environment is recommended.

State of trace element contamination of sediments from the Nangbéto hydroelectric dam lake (Togo)

The Nangbéto hydroelectric dam lake, which is a spillway for agricultural input residues, urban and industrial effluents present in the Mono basin, is exposed to all forms of pollution. The aim of this work is to estimate the content of seven trace elements present in the sediments of the aforementioned lake in order to assess the ecological risk incurred by the aquatic biocenosis and therefore by man. Forty-two sediment samples (21 per season) are realized in different areas of the Lake. Cd, Pb, Ni, Cu, Cr, As and Hg are measured out in the sediments by the flame atomic absorption spectrophotometer in these pre-mineralized samples. The results show average contents varying from the lowest level 0.04 mg / kg for Hg to the highest 12.15 mg / kg for Cu in the rainy season and from 0.03 mg / kg for Hg and for As to 9.14 mg/kg for Cu in the dry season. All of these values are below Canadian sediment quality standards. The strongest average geoaccumulation indices (Igeo) are obtained for Pb with values less than 2. The mean values of the contamination factor (FC) are less than 1. The mean indices of contamination (Im) are less than 2, threshold d 'an onset of polymetallic contamination. The ecological risk (Ri) in relation to the contamination of the sediments of the Lake with trace elements is low in any season (Ri <40) and this implies a low risk of contamination of the biocenosis. However, the present study only deals with metallic trace elements. It does not take into account other pollutants, nor the potential "cocktail" effects between them. Additional work should therefore be continued in this direction to consolidate the low risk recorded for the biocenosis. Le Lac du barrage hydroélectrique de Nangbéto qui constitue un déversoir des résidus des intrants agricoles, des effluents urbains et industriels présent dans le bassin du Mono est exposé à toutes formes de pollution. Le but de ce travail est de quantifier les teneurs de sept (7) éléments traces dans les sédiments dudit Lac afin d’évaluer le risque écologique encouru par la biocénose aquatique et partant par l’homme.Quarante-deux (42) échantillons de sédiments (21 par saison) sont échantillonnés dans différentes zones du Lac. Le Cd, Pb, Ni, Cu, Cr, As et Hg sont dosés dans les sédiments par le spectrophotomètre d’absorption atomique à flamme dans ces échantillons minéralisés. Les résultats montrent des teneurs moyennes variant de la plus faible teneur 0,04mg/kg pour le Hg à la plus forte (12,15mg/kg) pour le Cu en saison pluvieuse et de 0,03 mg/kg pour le Hg et pour l’As à la plus forte (9,14 mg/kg) pour le Cu en saison sèche. Toutes ces valeurs sont inférieures aux normes canadiennes de qualité des sédiments. Les plus forts indices de géoaccumulation (Igeo) moyens sont obtenus chez le Pb avec des valeurs inférieures à 2. Les valeurs moyennes de facteur de contamination (FC) sont inférieures à 1. Les indices moyens de contamination (Im) sont inférieurs à 2, seuil d’un début de contamination polymétallique. Le risque écologique (Ri) par rapport à la contamination des sédiments du Lac en éléments traces est faible en toute saison (Ri < 40) et cela implique un faible risque de contamination de la biocénose. La présente étude ne porte toutefois que sur les éléments traces métalliques. Elle ne tient compte ni des autres polluants, ni des effets "cocktail" potentiels entre eux. Un travail complémentaire devra donc être poursuivi dans ce sens pour consolider le faible risque enregistré pour la biocénose.

Amazonian House-ing: A Visual Anthropology Essay

This visual essay documents the house-ing practices of Amazonian river dwellers and urban and peri-urban residents in the face of large-scale development projects. In Altamira (Pará, Brazil), the construction of the third-largest hydroelectric dam in the world, the Belo Monte Plant, has led to the flooding of housing areas along rivers and the displacement of residents into collective urban resettlements. Although the complexities of people’s living did not enter the engineers’ calculations or the public policy agenda, the residents improvised construction materials and aesthetic repertoires to preserve the relationships that constituted their local ecologies. Our visual ethnography aims to re-center the situated purview of the resettled, re-visibilizing the house as an index of ineffaceable livelihood and as an ongoing terrain of contestation and continuous Amazonization. Resumo Este ensaio visual documenta as práticas de house-ing de ribeirinhos e habitantes urbanos e peri-urbanos da Amazônia, confrontados com grandes projetos de desenvolvimento. Em Altamira (Pará, Brasil), a construção da terceira maior hidroelétrica do mundo, a usina de Belo Monte, conduziu ao alagamento de áreas habitacionais e ao deslocamento de seus moradores para novos assentamentos urbanos coletivos. Embora as especificidades do mundo vivido dessas pessoas não tenham entrado no cálculo dos engenheiros, nem na agenda das políticas públicas, os moradores improvisaram materiais construtivos e repertórios estéticos para preservar as relações que constituíam suas ecologias locais. Esta etnografia visual busca restituir a perspectiva situada dos deslocados, dando visibilidade à casa como índice dos modos de viver e como um terreno aberto de contestação e de contínua amazonização. Resumen Este ensayo visual documenta las prácticas de house-ing de los ribereños y de los habitantes urbanos y periurbanos de Amazonia que se enfrentan a grandes proyectos de desarrollo. En Altamira (Pará, Brasil), la construcción de la tercera mayor represa hidroeléctrica del mundo, la usina Belo Monte, provocó la inundación de áreas de vivienda y el desplazamiento de sus habitantes a nuevos asentamientos urbanos colectivos. Aunque las especificidades del mundo vivido por estas personas no entraron en los cálculos de los ingenieros ni en la agenda de las políticas públicas, la gente improvisa materiales de construcción y repertorios estéticos para preservar las relaciones que constituían sus ecologías locales. Esta etnografía visual pretende recuperar la perspectiva de los desplazados, dando visibilidad a la casa como índice de formas de vida y como terreno abierto a la permanente contestación y amazonización.

Floristic diversity and conservation value of the biodiversity refuge area of the Soubré hydroelectric dam (South-West of Côte d'Ivoire)

After the establishment of the biodiversity conservation area of the Soubré hydroelectric dam, scientific studies showing its value as a biodiversity reserve and its importance for the population were not implemented. As a result, no sustainable management strategy has been initiated. this study was conducted to make up for this shortcoming. It aims to assess its conservation value. The data collection methodology combined botanical inventories and an ethnobotanical survey. The analyse of data was based on the plant diversity and the importance of the area for local populations. Investigations show a rich flora of 346 species. There are 38 endemic species, 10 vulnerable and 8 locally threatened with extinction. This flora richness allows to attribute to the conservation area the High Conservation Value of category 1 (HCV 1). Among the species list, 84 are cited by the populations as useful plants. The use categories are, in order of importance, medicinal use, food use, Handicrafted use, timber. The organs sought are mainly the leaves in the practice of traditional medicine, the fruits in food and the stem in crafts, timber and firewood. Among useful species, 13 are very important for local population. Of these, 6 are less abundant in the area such as Ricinodendron heudelotii, Carpolobia lutea G. Don. The capacity for the area to serve as a refuge for useful species gives it the HCV 5. These results will allow the implementation of appropriate management.

Development of a technology for collecting and analyzing data for monitoring based on an ontological approach

One of the ways to build information models is ontological modeling. The use of ontologies greatly facilitates the exchange of data between embedded models and utilities for the digital representation of an object or a real-world system, sometimes called “digital twin” (DT). It is also important to establish a correspondence between the DT, people and external programs. Based on the dictionary of the main terms, classes, objects of the subject area and the relations between them, we have built an ontology of the hydroelectric dam DT.