Extraction de sables et tendance à l'incision du Niger supérieur (Mali)

Ferry, Luc; Miétton, Michel; Muther, Nadine; Martin, Didier; Coulibaly, N’Tjie; Laval, Myriam; Basselot, F.; Coulibaly, Y.; Collerie, Mathilde; Croix, Kévin de La; Olivry, Jean-Claude

doi:10.4000/geomorphologie.9966

Cited by 7 publications

(7 citation statements)

References 6 publications

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“…The alluvial sand is made up of sediment transported or deposited by the rivers following the erosion of the watershed. Two methods of exploitation are used for this sand: the direct taking in the minor bed of the watercourse in full water and loading on dugout canoes (sand of the Oubangui in Impfondo), the direct taking in the dried alluvial zone and loading in dump trucks (sand of the Congo river after the bridge of Djoué), the dredging of the sand constituting benches hindering the navigation and rejection in edge for formation of heaps to be valorized This sand is comparable to that obtained by the exploitation of the Niger River and used for urbanization in Bamako [33,4]. The direct removal of sand from riverbeds is destructive to the environment.…”

Section: Typology Of Geomaterials Deposits In Congomentioning

confidence: 62%

“…The direct removal of sand from riverbeds is destructive to the environment. Indeed, this type of removal is a cause of the modification of riverbanks that can go as far as the incision of the channel, and thus disruption of hydrological regimes, it is also attributed to the destruction of forest areas and the disappearance of many animal and plant species [4,6]. This kind of extraction has already been decried in Europe and is considered a threat to the global environment [16].…”

Section: Typology Of Geomaterials Deposits In Congomentioning

confidence: 99%

“…These materials are mined in the form of sand, gravel, clay, laterite, limestone, granite, ... [2], and used directly or broken up into aggregates, allowing the erection of buildings essential for the functioning of modern societies. However, the removal of natural resources and their preparation for use is damaging to the environment [3][4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

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Environmental Impacts of Geomaterials Exploitation in the Republic of Congo

Watha-Ndoudy¹,

Dipakama²,

Nzila³

et al. 2022

AJEP

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Geomaterials are extracted everywhere in Congo, generally without environmental and social impact studies. The objective of this study was to assess their exploitation and the associated environmental consequences. Data were collected through interviews and field surveys. A total of 163 quarry sites (17% industrial and 83% artisanal) were studied, with an annual production of nearly 52 million tons. The activity is carried out either in the open air or in water. Three types of materials are exploited: soft (65%), hard (35%) and smooth (0.1%). The activity is mainly centered around urban agglomerations, and sand and gravel are the most prized geomaterials, regardless of the type of exploitation. The geomaterials exploited come either from primary rocks (granite and quartzite) or from the products of their dismantling (accumulations of gravel, sandstone, recent sands or laterites). The various mining processes use, from extraction to finishing, incoming flows in the form of consumable materials (oils, greases, tires, etc.), in the form of energy (fuel, electricity, etc.), and in the form of water, in the form of energy (hydrocarbons, engines or explosives), water and outflows in the form of solid (abandoned gravel heaps), atmospheric (dust, gas, vapors) and liquid (lubricants, fuels, water for washing materials) discharges that induce various pollutions that affect all the compartments of the environment (physical environment, biodiversity, health and human well-being). The impacts of artisanal mining are mostly medium and minor, with only 18% of major impacts, in contrast to industrial mining, which generates 55% of major impacts and appears to be the most degrading for the environment. Despite of the legislative and regulatory texts, the exploitation sites are abandoned without any rehabilitation, which impacts the environment for a long time. To impulse a sustainable management of the activity, proposals have been made.

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Section: Typology Of Geomaterials Deposits In Congomentioning

confidence: 62%

Section: Typology Of Geomaterials Deposits In Congomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Environmental Impacts of Geomaterials Exploitation in the Republic of Congo

Watha-Ndoudy¹,

Dipakama²,

Nzila³

et al. 2022

AJEP

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“…Hydropower dams have already been reported to affect the sediment flux in the lower Sanaga River (Ngoupayou et al 2016). Rising sand extraction may amplify such geomorphological change by increasing riverbed incision, as already observed in the Niger River (Ferry et al 2012). Consequences may include the deforestation of riparian areas, reductions in species populations, and possibly the local disappearance of animal and plant species, even if such cases have not as yet been reported.…”

Section: Sand Extractionmentioning

confidence: 92%

The Sanaga River, an Example of Biophysical and Socio-Cultural Integration in Cameroon, Central Africa

Togouet¹,

Tchatcho²,

Tharme³

et al. 2023

River Culture: Life as a Dance to the Rhythm of the Waters

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The Sanaga River is the largest in Cameroon and one of the main resources for the economic development of the country. A lack of electricity is one of the primary setbacks for the Cameroonian economy, and the national authorities plan to at least double, from 2,000 MW, the nation's hydropower electricity supply by 2035. Representing more than 75% of the estimated total hydro potential of Cameroon, the Sanaga River has one of the greatest hydropower potentials in Africa. As well as being a vital asset for the national economy, it possesses exceptional natural features such as waterfalls, biodiversity hotspots with endemic and rare wildlife (e.g., the West African manatee, hippopotamus, chimpanzee and forest elephant), and very high cultural diversity, with numerous ethnic groups represented. There are many human activities along the river (use of water resources for food security and irrigated agriculture, inland fisheries, intensive aquaculture, sand extraction and hydropower production) that are increasing, and with visibly detrimental effects. The construction of dams has forced the local population to move from one livelihood activity to another. The unique cultural heritage and biodiversity are hence under pressure, due to over-fishing, logging, hunting, agrochemical pollution and habitat destruction. Unfortunately, the management actions necessary for remediation of these detrimental impacts are not well captured in basin development plans. It is therefore considered urgent to implement more sustainable human activities, including the development of alternative economic resources, such as ecotourism.

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“…/s serait assuré, même pendant les périodes de déficit en énergie. Si le soutien des débits d'étiage peut évidemment être profitable pour le développement par recours au moto-pompage de cultures de contre-saison à l'instar de ce que l'on constate au Mali en particulier à l'aval du barrage de Sélingué (Ferry et al, 2012), il peut aussi représenter une contrainte au niveau de la traversée du cours d'eau par les hommes et le bétail durant la saison sèche. Par ailleurs, le maintien de la pêche traditionnelle de Baro en mai suppose que la mare demeure à son plus bas niveau à cette date.…”

Section: Photounclassified