Evolution des régimes hydrologiques en région équatoriale camerounaise: un impact de la variabilité climatique en Afrique équatoriale?

Lienou, Gaston; Mahé, Gil; Paturel, Jean Emmanuel; Servat, Éric; Sighomnou, D.; Ekodeck, Georges Emmanuel; Dezetter, Alain; Dieulin, Claudine

doi:10.1623/hysj.53.4.789

Cited by 57 publications

(64 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This variability might be due to anthropogenic activities, influence of Atlantic Ocean and global climate change. Similar results were documented in Equatorial Central Africa on the variability of the hydrographic regime [26] [27]. The strong correlation observed between rainfalls and relative wetness shows that the atmosphere of these zones, does not exchange only heat with the ocean, but also of water vapor and rains.…”

Section: Characteristic Of Environmental Variablessupporting

confidence: 82%

Influence of Anthropogenic Pollution on the Abundance Dynamics of Some Freshwater Invertebrates in the Coastal Area of Cameroon

Koji¹,

Ewoti²,

Onana³

et al. 2017

JEP

View full text Add to dashboard Cite

The abundance dynamic of some freshwater invertebrates in relation with the abiotic factors of the medium was studied from March 2013 to March 2014 on the main streams of the Wouri and Sanaga basins. Individuals of Copepoda, Atyidae, Chironomidae and Physidae were collected, identified and counted. Samplings were carried out monthly; meanwhile measurements of the environmental variables were taken. Results of the physico-chemical analyses revealed that water of the Sanaga basin is globally well oxygenated (77% -92%) and faintly mineralized (14 -107 µS/cm), excepted in the stations receiving household pollutants. Inversely, in the Wouri basin, waters are hypoxic with high content of organic matters (27.79 ± 9.43 mg/L). During rainy season (June-September), there is a dilution-dispersion of the organic matter due to stormwaters. Concerning biological analyses, the families of Physidae and Chironomidae were more abundant in urban stations than in stations situated in suburban area, especially during low water level period, showing that they are well adapted to anthropogenic and organic pollutions. The hypoxic conditions of urban waterways do not favor the proliferation of sensitive taxa such as Atyidae and Copepoda. These taxa preferred well oxygenated waters with rapid flow, and are more abundant during rainy season in stations located in suburban area or which are less subjected to anthropogenic disturbances.

show abstract

Section: Characteristic Of Environmental Variablessupporting

confidence: 82%

Influence of Anthropogenic Pollution on the Abundance Dynamics of Some Freshwater Invertebrates in the Coastal Area of Cameroon

Koji¹,

Ewoti²,

Onana³

et al. 2017

JEP

View full text Add to dashboard Cite

show abstract

“…Thus, we suppose that reduced flows would be due to an overall decrease in precipitation over the watershed of Wadi Mina [47]. Small changes in precipitation can have significant impact on the flow of surface water [145]. In fact, climate is recognized to be the main factor in semi-arid Mediterranean areas of Algeria which experience short and intense rain episodes, high evaporating power of wind, prolonged droughts and freezing and thawing cycles [42,45,46].…”

Section: Discussionmentioning

confidence: 99%

Erosion, Suspended Sediment Transport and Sedimentation on the Wadi Mina at the Sidi M’Hamed Ben Aouda Dam, Algeria

Hallouz

Meddi

Mahé

et al. 2018

Water

View full text Add to dashboard Cite

Abstract:The objective of this study was to follow-up on the evolution of the hydro-pluviometric schemes and particular elements of Wadi Mina (6048 km 2 ) to the Sidi M'Hamed Ben Aouda Dam to evaluate the silting origin and status of this dam situated in the northwest of Algeria. The pluviometric study targeted a series of rains during 77 years , the liquid discharge data cover a period of 41 years and the solids and suspended sediment concentrations data cover very variable periods, starting from 22 to 40 years for the entire catchment area. The statistical tests for ruptures detection on the chronological series of rains and discharges indicate a net reduction of rains of more than 20% on the entire basin since 1970. The evolution of solids inputs was quantified: the maximum values are registered on autumn start and at the end of spring. The Wadi Mina basin brings annually 38 × 10 6 m 3 of water with a specific degradation of 860 t·km −2 ·year −1 . By comparing the results found, we thus observe that the basin upstream of SMBA (1B) Dam is the greatest sediment producer towards the dam because it shows a specific degradation equal to 13.36 t·ha −1 ·year −1 .

show abstract

“…La plupart de ces travaux ont surtout porté sur l'Afrique de l'Ouest sahélienne sur des bassins de superficie très réduite (5 à 1000 km 2 ) et ont montré la diminution des crues induite par la baisse des lames d'eau précipitées. En effet, cette baisse du niveau de l'eau dans les cours et plans d'eau en Afrique de l'Ouest et Centrale est plus marquée au cours des décennies 1970 et 1980, en lien avec la diminution des précipitations observées (Mahé 1993, Mahé et Olivry 1995, Paturel et al 2003, Le Lay et Galle 2005, Lienou 2008, Amoussou et al 2012. En revanche, la légère reprise des précipitations depuis la fin des années 1990 en Afrique de l'Ouest en général et au Bénin-Togo en particulier, dans un environnement de plus en plus marqué par la pression anthropique, a entraîné une augmentation des écoulements et des crues dans les cours d'eau par rapport aux décennies 1970 et 1980 (Amoussou 2010).…”

Section: Introductionunclassified

Dynamique et modélisation des crues dans le bassin du Mono à Nangbéto (Togo/Bénin)

Amoussou

Tramblay

Totin

et al. 2014

Hydrological Sciences Journal

View full text Add to dashboard Cite

Reçu le 29 avril 2013; accepté le 28 octobre 2013; la discussion concernant cet article est ouverte jusqu'au 1er mai 2015Editeur Z.W. Kundzewicz; Editeur associé B. Touaibia Résumé Les inondations des dernières années en Afrique de l'Ouest rendent nécessaire la prévision hydrologique pour réduire la vulnérabilité des populations. Nous avons étudié la dynamique des crues dans le bassin du Mono en amont du barrage de Nangbéto (Togo et Bénin) par des méthodes statistiques et déterministes. L'augmentation des précipitations au cours de la décennie 1990 et la mise en eau du barrage de Nangbéto en 1988 ont modifié le régime du Mono, dont les débits d'étiages ont augmenté. Les débits entrants et sortants du barrage sont équivalents, même lors des crues. Les maximums annuels des débits entrants peuvent être modélisés par une distribution des valeurs extrêmes (GEV) de type Fréchet, tandis que ceux des débits sortants, suivent une loi GEV de type Weibull (bornée). Le mécanisme dominant de génération des crues dans le bassin est la montée progressive des eaux associée à l'augmentation de la saturation des sols. L'analyse des débits de crue entre 1988 et 2010 n'a pas montré d'augmentation de la magnitude ou de la fréquence des crues. Le modèle GR4J reproduit bien les débits de crues en période calage, mais ces critères de performance se dégradent lorsque l'on s'en éloigne. Dans ces conditions, l'utilisation de ce modèle pour évaluer les risques futurs de crues serait hasardeuse et il est nécessaire d'envisager d'autres types d'approches.Mots clefs Bénin-Togo ; bassin Mono ; barrage de Nangbéto ; crues ; GR4J ; statistiques ; extrêmes Dynamics and modelling of floods in the river basin of Mono in Nangbeto, Togo/Benin Abstract The devastating floods in recent years in West Africa call for improvement in hydrological forecasts to reduce the vulnerability of local communities. We studied flood dynamics in the Mono basin, in Togo and Benin, upstream of the Nangbeto Dam, using statistical methods. The increase in precipitation in the 23-year period from 1988 (following completion of the Nangbeto Dam) modified the regine of the Mono River, with an increase in stage discharge. There is little difference between the river discharge at the entrance and the exit of the Nangbeto Reservoir, at least at peak flow, which emphasizes that the dam, due to the small capacity of the reservoir, has a limited effect on flow regulation. The annual peak flows entering the reservoir can be modelled using a Frechet-type generalized extreme value (GEV) distribution, while those at the exit follow a Weibulltype GEV distribution. The main mechanism for peak flow generation in the basin is a steady rise of water as a result of increasing soil moisture saturation, rather than isolated rain spells. Peak flows between 1988 and 2010 do not show any change in magnitude and frequency. The GR4J hydrological model is shown to be effective in reproducing peak flows, but its skill decreases as we move away from the calibration period. Therefore, it may be risky t...

show abstract

Evolution des régimes hydrologiques en région équatoriale camerounaise: un impact de la variabilité climatique en Afrique équatoriale?

Cited by 57 publications

References 13 publications

Influence of Anthropogenic Pollution on the Abundance Dynamics of Some Freshwater Invertebrates in the Coastal Area of Cameroon

Influence of Anthropogenic Pollution on the Abundance Dynamics of Some Freshwater Invertebrates in the Coastal Area of Cameroon

Erosion, Suspended Sediment Transport and Sedimentation on the Wadi Mina at the Sidi M’Hamed Ben Aouda Dam, Algeria

Dynamique et modélisation des crues dans le bassin du Mono à Nangbéto (Togo/Bénin)

Contact Info

Product

Resources

About