[ Modélisation hydrodynamique de l’aquifère côtier du Saloum (Centre Ouest du Sénégal) par approche stochastique ]
Volume 46, Issue 1, July 2025, Pages 112–123
Seyni NDOYE1, Hamza Brahim Mahamat2, Amadou Sarr3, Mathieu Le Coz4, Arnaud Gauthier5, Cheikh Bécaye GAYE6, Philippe Le Coustumer7, and Moumtaz RAZACK8
1 Université Cheikh Anta Diop, Ecole Supérieure Polytechnique, Département de Génie Civil, BP 5085 Dakar Fann, Senegal
2 Polytechnic University of Mongo, Faculty of Mines and Geology, BP 4377 Mongo, Chad
3 Université Cheikh Anta Diop, Faculté des Sciences et Techniques, Département de Géologie, BP 5005 Dakar Fann, Senegal
4 University of Poitiers, CNRS, UMR 7285 IC2MP, 40 Avenue du Recteur Pineau, 86022 Poitiers Cedex, France
5 Civil Engineering and Geo-Environment Laboratory, Faculty of Science and Technology, University of Lille, Villeneuve-d’Ascq, France
6 Université Cheikh Anta Diop, Faculté des Sciences et Techniques, Département de Géologie, BP 5005 Dakar Fann, Senegal
7 Bordeaux Imaging Center, University of Bordeaux, Bordeaux, France
8 Department of Hydrogeologye UMR 7185, University of Poitiers, France
Original language: French
Copyright © 2025 ISSR Journals. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Water supply in the Saloum area is provided by the groundwater in the sandy-clay formations of the Continental Terminal. The presence of hypersaline waters from the Saloum River in the north and the ocean in the west, climate change and population growth are threatening groundwater resources, hence the need for a better understanding of the aquifer system. The aim of this work is to establish a hydrodynamic model that can reproduce the behaviour of flows by identifying the main recharge and evaporation mechanisms and estimating the hydrodynamic properties. The heterogeneity of the geological formation is at the root of a very large variation in the hydraulic parameters. This heterogeneity and the very limited uncertainty in the data justify opting for a stochastic modelling approach. The modelling is carried out under steady state conditions with imposed loads in order to quantify the natural flows passing through the aquifer and to understand the distribution of hydrodynamic parameters in order to reconstruct the piezometry. The probability densities for the values of permeability and recharge obtained indicate a high sensitivity of the simulations to these two parameters. The hydraulic conductivity values oscillate between 10-2 and 10-5 m.s-1 and are identical to those obtained by test pumping. The overall average balance shows a perfect balance between inflow and outflow. The average annual recharge of 13.98 mm is provided mainly by rainwater, and evapotranspiration is 13.65 mm. The model, which is deemed acceptable under steady-state conditions, will serve as the basis for modelling saline intrusion.
Author Keywords: Modelling, Stochastic, Aquifer, Saloum, Senegal.
Volume 46, Issue 1, July 2025, Pages 112–123
Seyni NDOYE1, Hamza Brahim Mahamat2, Amadou Sarr3, Mathieu Le Coz4, Arnaud Gauthier5, Cheikh Bécaye GAYE6, Philippe Le Coustumer7, and Moumtaz RAZACK8
1 Université Cheikh Anta Diop, Ecole Supérieure Polytechnique, Département de Génie Civil, BP 5085 Dakar Fann, Senegal
2 Polytechnic University of Mongo, Faculty of Mines and Geology, BP 4377 Mongo, Chad
3 Université Cheikh Anta Diop, Faculté des Sciences et Techniques, Département de Géologie, BP 5005 Dakar Fann, Senegal
4 University of Poitiers, CNRS, UMR 7285 IC2MP, 40 Avenue du Recteur Pineau, 86022 Poitiers Cedex, France
5 Civil Engineering and Geo-Environment Laboratory, Faculty of Science and Technology, University of Lille, Villeneuve-d’Ascq, France
6 Université Cheikh Anta Diop, Faculté des Sciences et Techniques, Département de Géologie, BP 5005 Dakar Fann, Senegal
7 Bordeaux Imaging Center, University of Bordeaux, Bordeaux, France
8 Department of Hydrogeologye UMR 7185, University of Poitiers, France
Original language: French
Copyright © 2025 ISSR Journals. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Water supply in the Saloum area is provided by the groundwater in the sandy-clay formations of the Continental Terminal. The presence of hypersaline waters from the Saloum River in the north and the ocean in the west, climate change and population growth are threatening groundwater resources, hence the need for a better understanding of the aquifer system. The aim of this work is to establish a hydrodynamic model that can reproduce the behaviour of flows by identifying the main recharge and evaporation mechanisms and estimating the hydrodynamic properties. The heterogeneity of the geological formation is at the root of a very large variation in the hydraulic parameters. This heterogeneity and the very limited uncertainty in the data justify opting for a stochastic modelling approach. The modelling is carried out under steady state conditions with imposed loads in order to quantify the natural flows passing through the aquifer and to understand the distribution of hydrodynamic parameters in order to reconstruct the piezometry. The probability densities for the values of permeability and recharge obtained indicate a high sensitivity of the simulations to these two parameters. The hydraulic conductivity values oscillate between 10-2 and 10-5 m.s-1 and are identical to those obtained by test pumping. The overall average balance shows a perfect balance between inflow and outflow. The average annual recharge of 13.98 mm is provided mainly by rainwater, and evapotranspiration is 13.65 mm. The model, which is deemed acceptable under steady-state conditions, will serve as the basis for modelling saline intrusion.
Author Keywords: Modelling, Stochastic, Aquifer, Saloum, Senegal.
Abstract: (french)
L’alimentation en eau dans la zone du Saloum est assurée par la nappe sablo-argileuses du Continental Terminal. La présence des eaux hypersalées du fleuve Saloum au nord et l’océan l’Ouest, les changements climatiques, l’accroissement de la population constituent une menace accrue sur les ressources en eau souterraine d’où un besoin d’une meilleure compréhension du système aquifère. Ce travail cherche à établir un modèle hydrodynamique permettant de reproduire le comportement des écoulements à travers l’identification des principaux mécanismes de recharge, d’évaporation et l’estimation des propriétés hydrodynamiques. L’hétérogénéité de la formation géologique est à l’origine d’une très forte variation des paramètres hydrauliques. Cette hétérogénéité et l’incertitude des données très réduites conduisent à opter pour une approche de modélisation stochastique. La modélisation est faite en régime permanent en charge imposée pour la quantification des débits naturels transitant dans l’aquifère et la connaissance de la distribution des paramètres hydrodynamiques permettant la reconstitution de la piézométrie. Les densités de probabilité pour les valeurs de perméabilité et de la recharge peu étalées obtenues indiquent une forte sensibilité des simulations à ces deux paramètres. Les valeurs de conductivité hydraulique oscillent entre 10-2 et 10-5 m.s-1 et sont identiques à celles obtenus par pompage d’essai. Le bilan global moyen montre un équilibre parfait entre les débits d’entrée et de sortie. La recharge annuelle moyenne de 13,98 mm est assurée pour l’essentiel par les eaux de pluie et l’évapotranspiration est de 13,65 mm. Le modèle jugé acceptable en régime permanent va servir de base pour la modélisation de l’intrusion saline.
Author Keywords: Modélisation, Stochastique, Aquifère, Saloum, Sénégal.
How to Cite this Article
Seyni NDOYE, Hamza Brahim Mahamat, Amadou Sarr, Mathieu Le Coz, Arnaud Gauthier, Cheikh Bécaye GAYE, Philippe Le Coustumer, and Moumtaz RAZACK, “Hydrodynamic modelling of the Saloum coastal aquifer (central western Senegal) using stochastic approach,” International Journal of Innovation and Applied Studies, vol. 46, no. 1, pp. 112–123, July 2025.
