Morphological and sedimentological changes in the Senegal River estuary after the constuction of the Diama dam

Barusseau, Jean-Paul; Bâ, Mariline; Descamps, Cyr; Diop, E. S.; Diouf, Bachir; Kane, Alioune; Saos, J. L.; Soumaré, Abdoulaye

doi:10.1016/s0899-5362(98)00014-1

Cited by 38 publications

(15 citation statements)

References 3 publications

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“…These observations and the satellite data also provide insight on the sand sourcing the seaward face of the Langue de Barbarie, which is derived from the coast and shoreface of Mauritania updrift of the historic mouth of the Senegal (Figure 1), in agreement with a conclusion also reached by Barusseau et al [25]. The satellite data show that the Langue de Barbarie spit is a 100-400 m-wide feature.…”

Section: Lst and Growth Dynamics Of The Langue De Barbarie Spitsupporting

confidence: 89%

Shoreline Changes on the Wave-Influenced Senegal River Delta, West Africa: The Roles of Natural Processes and Human Interventions

Sadio

Anthony

Diaw

et al. 2017

Water

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Abstract:The Senegal River delta in West Africa, one of the finest examples of "wave-influenced" deltas, is bounded by a spit periodically breached by waves, each breach then acting as a shifting mouth of the Senegal River. Using European Re-Analysis (ERA) hindcast wave data from 1984 to 2015 generated by the Wave Atmospheric Model (WAM) of the European Centre for Medium-Range Weather Forecasts (ECMWF), we calculated longshore sediment transport rates along the spit. We also analysed spit width, spit migration rates, and changes in the position and width of the river mouth from aerial photographs and satellite images between 1954 and 2015. In 2003, an artificial breach was cut through the spit to prevent river flooding of the historic city of St. Louis. Analysis of past spit growth rates and of the breaching length scale associated with maximum spit elongation, and a reported increase in the frequency of high flood water levels between 1994 and 2003, suggest, together, that an impending natural breach was likely to have occurred close to the time frame of the artificial 2003 breach. Following this breach, the new river mouth was widened rapidly by flood discharge evacuation, but stabilised to its usual hydraulic width of <2 km. In 2012, severe erosion of the residual spit downdrift of the mouth may have been due to a significant drop (~15%) in the longshore sand transport volume and to a lower sediment bypassing fraction across the river mouth. This wave erosion of the residual spit led to rapid exceptional widening of the mouth to~5 km that has not been compensated by updrift spit elongation. This wider mouth may now be acting as a large depocentre for sand transported alongshore from updrift, and has contributed to an increase in the tidal influence affecting the lower delta. Wave erosion of the residual spit has led to the destruction of villages, tourist facilities and infrastructure. This erosion of the spit has also exposed part of the delta plain directly to waves, and reinforced the saline intrusion within the Senegal delta. Understanding the mechanisms and processes behind these changes is important in planning of future shoreline management and decision-making regarding the articulations between coastal protection offered by the wave-built spit and flooding of the lower delta plain of the Senegal River.

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Section: Lst and Growth Dynamics Of The Langue De Barbarie Spitsupporting

confidence: 89%

Shoreline Changes on the Wave-Influenced Senegal River Delta, West Africa: The Roles of Natural Processes and Human Interventions

Sadio

Anthony

Diaw

et al. 2017

Water

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“…The Alqueva dam is expected to amplify coastal erosion (Del Río et al 2002); however its harshness is unknown. Similar situations are already documented for other Portuguese (Dias et al 2000, Veloso-Gomes 2002 and worldwide coastal areas (Ly 1980, Palanques et al 1990, Barusseau et al 1998, Chen & Zong 1998). …”

Section: Water Quantity and Sediment Loadsupporting

confidence: 84%

Review on the major ecosystem impacts caused by damming and watershed development in an Iberian basin (SW-Europe): focus on the Guadiana estuary

Morais

2008

Ann. Limnol. - Int. J. Lim.

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The Guadiana estuary (Iberian Peninsula, Europe) has low agriculture, industry and urban pressure, unlike other major Iberian estuaries; however, this situation is about to change. The Alqueva dam was constructed at 150 km from the river mouth, creating one of the biggest artificial lakes in Europe, which will support 110 000 ha of irrigation areas. Moreover, the estuarine margins are suffering increased human pressure. The risks that the Alqueva dam will pose to the downstream ecosystems, mainly to the estuary and adjacent coastal area, will be reviewed in this paper. Other issues are also analysed, as increased human desertification in the Portuguese basin, real estate pressure and the impact of the construction of a public infrastructure in the Portuguese lower estuary. Increased problems of sediment load reduction, water quality deterioration and shifts in the downstream fish populations are expected due to higher river flow reduction. Irreversible changes to estuarine margins and increased risk of pollution in the estuary will result from the multiple urban pressures. Lack of forest management and increased risk of wildfires, leading to water quality degradation and increased soil erosion, are a result of human desertification in the upper Portuguese basin. Multiple solutions to tackle these problems have to be considered. Creating the International Natural Park of the Lower Guadiana would not be enough and tourism should not be regarded as the only way to develop such a poor region. An ecohydrological approach of the basin should be implemented, to establish scientific based solutions to help solving conflicts and testing scenarios. Ultimately, the creation of a Portuguese-Spanish Basin Management Council for the lower Guadiana, involving those that are interested in the sustainable development of the Guadiana (local populations and associations, private stakeholders (dam managers, tourism entrepreneurs, farmers), local and national authorities, ENGO's and scientists) is essential to produce ecological and sustainable management decisions.

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“…Like all dams, Diama has created a boundary. Being an anti-salt barrier, Diama divides the upriver and downriver areas into two highly distinct hydrographical sectors with regards to water quality (Barusseau et al 1998). Within the estuary, it is still too early for a proper assessment of the impact of the artificial opening of Barbary Spit to be undertaken.…”

Section: Key Findingsmentioning

confidence: 99%

Large Dams and Uncertainties: The Case of the Senegal River (West Africa)

Dumas

Miétton

Hamerlynck

et al. 2010

Society & Natural Resources

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This paper examines the environmental and socio-economic consequences of hydraulic infrastructural changes along the Senegal River valley and estuary. During the 1980s, two dams were built along the valley floor to facilitate hydro-electrical production and regular water supply for crop irrigation. In 2003, a breach was dug across Barbary Spit to alleviate flooding in the nearby Saint-Louis city. Although these structures helped regulate the river flow, they also resulted in a series of unforeseen impacts. The study examines these, after on-site measurements (topometry, water salinity, piezometry), analysis of hydrological data, field observations, and surveys with dam managers, state regional directions and local stakeholders. It stresses the urgency of elaborating models of hydraulic management to limit the negative consequences of the hydraulic constructions. These models should consider the variety of water uses in the middle valley and delta, and also the water safety and quality (salinity) downriver from Diama Dam.

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Morphological and sedimentological changes in the Senegal River estuary after the constuction of the Diama dam

Cited by 38 publications

References 3 publications

Shoreline Changes on the Wave-Influenced Senegal River Delta, West Africa: The Roles of Natural Processes and Human Interventions

Shoreline Changes on the Wave-Influenced Senegal River Delta, West Africa: The Roles of Natural Processes and Human Interventions

Review on the major ecosystem impacts caused by damming and watershed development in an Iberian basin (SW-Europe): focus on the Guadiana estuary

Large Dams and Uncertainties: The Case of the Senegal River (West Africa)

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