Hydrogeological modeling is an interesting and widely-used approach to improving our understanding of groundwater, both to test existing hypotheses on the behavior of hydrosystems and to predict their responses to various natural or man-made problems. Today, software such as Leapfrog Geo offers the possibility of building a 3D geological model with a more accurate representation of the subsurface. Statistical tools such as ordinary kriging can be used to simulate the spatial distribution of groundwater. These modeling approaches were combined to improve knowledge of the groundwater flow context within three massifs on the island of Grande Comore. The delineation of the 3D geometry of litho-stratigraphic units has enabled a more detailed conceptualization of groundwater flows in a complex volcanic environment. Piezometric interpolations were used to validate aquifer geometry. It has been demonstrated that an implicit geological model coupled with piezometry can provide very interesting information on the hydrogeological configuration of a volcanic massif. In the Karthala and Badjini massifs, the respective confined and semi-confined configurations of the aquifers are observed, with thicknesses that progressively decrease with distance from the coast. In the Grille massif, on the other hand, the aquifer configuration is unconfined, with thickness increasing with distance from the coast. In all three massifs, the flow of water in the underground hydrosystems is from the central part towards the coast, naturally following the geological configuration of the ground. It should be noted that the absence of data in the central parts of the massifs still leaves uncertainties about the geometry in these parts of the aquifers. However, the models that have been established provide valid hypotheses for characterizing the hydrogeological configuration at the scale of each massif.
References
[1]
Marini, D. (1990) Résultas et interpretations d’une campagne de pompage d’essai sur des puits dans les aquifères de base de la Grande Comore. DCTD, Technique COI/79/005 et COI/86/001.
[2]
Ecker, A. (1976) Groundwater Behaviour in Tenerife, Volcanic Island (Canary Islands, Spain). Journal of Hydrology, 28, 73-86. https://doi.org/10.1016/0022-1694(76)90053-6
[3]
Custodio Gimena, E. (2025) Geohidrología de terrenos e islas volcánicas. https://dialnet.unirioja.es/servlet/libro?codigo=195829
[4]
Savin, C., Ritz, M., Join, J. and Bachelery, P. (2001) Hydrothermal System Mapped by CSAMT on Karthala Volcano, Grande Comore Island, Indian Ocean. Journal of Applied Geophysics, 48, 143-152. https://doi.org/10.1016/s0926-9851(01)00078-7
[5]
Bret, J., Join, L. and Coudray, J. (2000) Investigation on Deep Water Resources by Tunnels within the “Piton des Neiges” Volcano, Reunion Island. In: Sililo, O., Ed., Groundwater: Past Achievements and Future Challenges, A. A. Balkema, 1103-1106.
[6]
Cruz, V. and Silva, O. (2001) Hydrogeologic Framework of Pico Island, Azores, Portugal. Hydrogeology Journal, 9, 177-189. https://doi.org/10.1007/s100400000106
[7]
Izuka, S.K. and Gingerich, S.B. (2003) A Thick Lens of Fresh Groundwater in the Southern Lihue Basin, Kauai, Hawaii, USA. Hydrogeology Journal, 11, 240-248. https://doi.org/10.1007/s10040-002-0233-5
[8]
Join, J., Folio, J., Bourhane, A. and Comte, J. (2015) Groundwater Resources on Active Basaltic Volcanoes: Conceptual Models from La Réunion Island and Grande Comore. In: Bachelery, P., Lenat, J.F., Di Muro, A. and Michon, L., Eds., Active Volcanoes of the World, Springer, 61-70. https://doi.org/10.1007/978-3-642-31395-0_5
[9]
Lachassagne, P., Aunay, B., Frissant, N., Guilbert, M. and Malard, A. (2014) High‐resolution Conceptual Hydrogeological Model of Complex Basaltic Volcanic Islands: A Mayotte, Comoros, Case Study. Terra Nova, 26, 307-321. https://doi.org/10.1111/ter.12102
[10]
Anderson, M.P., Woessner, W.W. and Hunt, R.J. (2015) Modeling Purpose and Conceptual Model. In: Anderson, M.P., Woessner, W.W. and Hunt, R.J., Eds., Applied Groundwater Modeling, Elsevier, 27-67. https://doi.org/10.1016/b978-0-08-091638-5.00002-x
[11]
Ziegel, E.R., Deutsch, C.V. and Journel, A.G. (1998) Geostatistical Software Library and User’s Guide. Technometrics, 40, 357. https://doi.org/10.2307/1270548
[12]
Franke, R. (1982) Smooth Interpolation of Scattered Data by Local Thin Plate Splines. Computers & Mathematics with Applications, 8, 273-281. https://doi.org/10.1016/0898-1221(82)90009-8
[13]
Smirnoff, A., Boisvert, E. and Paradis, S.J. (2008) Support Vector Machine for 3D Modelling from Sparse Geological Information of Various Origins. Computers & Geosciences, 34, 127-143. https://doi.org/10.1016/j.cageo.2006.12.008
[14]
Hardy, R.L. (1971) Multiquadric Equations of Topography and Other Irregular Surfaces. Journal of Geophysical Research, 76, 1905-1915. https://doi.org/10.1029/jb076i008p01905
[15]
Zhexenbayeva, A., Madani, N., Renard, P. and Straubhaar, J. (2024) Using Multiple-Point Geostatistics for Geomodeling of a Vein-Type Gold Deposit. Applied Computing and Geosciences, 23, Article ID: 100177. https://doi.org/10.1016/j.acags.2024.100177
[16]
Wycisk, P., Hubert, T., Gossel, W. and Neumann, C. (2009) High-resolution 3D Spatial Modelling of Complex Geological Structures for an Environmental Risk Assessment of Abundant Mining and Industrial Megasites. Computers & Geosciences, 35, 165-182. https://doi.org/10.1016/j.cageo.2007.09.001
[17]
Burke, H., Morgan, D., Kessler, H. and Cooper, A. (2025) A 3D Geological Model of the Superficial Deposits of the Holderness Area. https://www.semanticscholar.org/paper/A-3D-geological-model-of-the-superficial-deposits-Burke-Morgan/d7352283fc4e51abba596e7166e05536a941beac
[18]
Martin, P.J. and Frind, E.G. (1998) Modeling a Complex Multi‐Aquifer System: The Waterloo Moraine. Groundwater, 36, 679-690. https://doi.org/10.1111/j.1745-6584.1998.tb02843.x
[19]
Berg, R.C., Mathers, S.J., Kessler, H. and Keefer, D.A. (2011) Synopsis of Current Three-Dimensional Geological Mapping and Modeling in Geological Survey Organizations. Illinois State Geological Survey Circular, Vol. 578.
[20]
Rosenberg, M.D., Bignall, G. and Rae, A.J. (2009) The Geological Framework of the Wairakei-Tauhara Geothermal System, New Zealand. Geothermics, 38, 72-84. https://doi.org/10.1016/j.geothermics.2009.01.001
[21]
Bignall, G., Milicich, S., Ramírez, L., Rosenberg, M., Kilgour, G. and Rae, A. (2010) Geology of the Wairakei-Tauhara Geothermal System, New Zealand. Proceedings World Geothermal Congress 2010, Bali, 25-29 April 2010, 30.
[22]
Milicich, S.D., Rae, A.J., Rosenberg, M.D. and Bignall, G. (2008) Lithological and Structural Controls on Fluid Flow and Hydrothermal Alteration in the Western Ohaaki Geothermal Field (New Zealand)—Insights from Recent Deep Drilling. Geothermal Resources Council, Transactions, 32, 303-307.
[23]
Milicich, S.D., et al. (2010) Stratigraphic Correlation Study of the Kawerau Geothermal Field. GNS Science Consultancy, Confidential Report to Mighty River Power Limited 2010/23.
[24]
Intergovernmental Panel on Climate Change (IPCC) (2023) Climate Change 2022—Impacts, Adaptation and Vulnerability. Cambridge University Press. https://doi.org/10.1017/9781009325844
[25]
INSEED (2017) Annuaire des données du RGPH 2017: Populations cibles des programmes de développement.
[26]
Flower, M.F.J. (1973) Trace-Element Distribution in Lavas from Anjouan and Grande Comore, Western Indian Ocean. Chemical Geology, 12, 81-98. https://doi.org/10.1016/0009-2541(73)90107-1
[27]
Hajash, A. and Armstrong, R.L. (1972) Paleomagnetic and Radiometric Evidence for the Age of the Comores Islands, West Central Indian Ocean. Earth and Planetary Science Letters, 16, 231-236. https://doi.org/10.1016/0012-821x(72)90195-1
[28]
Emerick, C.M. and Duncan, R.A. (1982) Age Progressive Volcanism in the Comores Archipelago, Western Indian Ocean and Implications for Somali Plate Tectonics. Earth and Planetary Science Letters, 60, 415-428. https://doi.org/10.1016/0012-821x(82)90077-2
[29]
Nougier, J., Cantagrel, J.M. and Karche, J.P. (1986) The Comores Archipelago in the Western Indian Ocean: Volcanology, Geochronology and Geodynamic Setting. Journal of African Earth Sciences (1983), 5, 135-145. https://doi.org/10.1016/0899-5362(86)90003-5
[30]
Upton, B.G.J. (1982) Oceanic Islands. In: Nairn, A.E.M. and Stehli, F.G., Eds., The Ocean Basins and Margins, Springer US, 585-648. https://doi.org/10.1007/978-1-4615-8038-6_13
[31]
Bachèlery, P. and Coudray, J. (1993) Carte géologique des Comores: Notice explicative de la carte volcano-tectonique de la Grande Comore (Ngazidja). Mission Francaise de la Copération.
[32]
BRGM (1964) Rapport hydrogéologique sur l’alimentation en eau de la ville de Moroni (Grande Comore). BRGM, Tananarive, Technique 64 A/25.
[33]
BRGM (1965) Alimentation en eau de la ville de Moroni (Grande Comore). Sondage de reconnaissance. BRGM, Tananarive, Technique 65 A/34.
[34]
BRGM (1970) Alimentation en eau de Moroni (Grande Comore), Puits TP1. BRGM, Tananarive, Technique 70/22.
[35]
BRGM (1972) Alimentation en eau de l’aérodrome de Hahaîa (Grande Comore) étude hydrogéologique et géophysique. BRGM, Tananarive, Technique 72/7.
[36]
DCTD (1986) Recherche et mise en valeur des eaux souterraines, rapport technique, Hydrogéologie de l’île de Ngazidja (Grande Comore), état des connaissance en juillet 1986.
[37]
DCTD (1987) Rapport technique des projets COI/79/005 et COI/86/001. Perspectives de mise en valeur des eaux souterraines pour l’alimentation en eau des agglomération de l’île de Ngazidja (Grande Comore). Moroni, Comore, Technique COI/79/005 et COI/86/001.
[38]
DCTD (1988) Les eaux souterraines de l’Afrique orientale, centrale et australe. RessourcesNaturelles, 19, 50-67.
[39]
Turner, R.J., Mansour, M.M., Dearden, R., Ó Dochartaigh, B.É. and Hughes, A.G. (2014) Improved Understanding of Groundwater Flow in Complex Superficial Deposits Using Three-Dimensional Geological-Framework and Groundwater Models: An Example from Glasgow, Scotland (UK). Hydrogeology Journal, 23, 493-506. https://doi.org/10.1007/s10040-014-1207-0
[40]
Artimo, A., Mäkinen, J., Berg, R.C., Abert, C.C. and Salonen, V. (2003) Three-dimensional Geologic Modeling and Visualization of the Virttaankangas Aquifer, Southwestern Finland. Hydrogeology Journal, 11, 378-386. https://doi.org/10.1007/s10040-003-0256-6
[41]
Cherry, D., Gill, B., Pack, T. and Rawling, T. (2011) Geoscience Australia and GeoScience Victoria: 3-D Geological Modeling Developments in Australia. 19-24. https://www.researchgate.net/publication/281786125_Geoscience_Australia_and_GeoScience_Victoria_3-D_Geological_Modeling_Developments_in_Australia
[42]
Robins, N.S., Rutter, H.K., Dumpleton, S. and Peach, D.W. (2005) The Role of 3D Visualisation as an Analytical Tool Preparatory to Numerical Modelling. Journal of Hydrology, 301, 287-295. https://doi.org/10.1016/j.jhydrol.2004.05.004
[43]
Spottke, I., Zechner, E. and Huggenberger, P. (2005) The Southeastern Border of the Upper Rhine Graben: A 3D Geological Model and Its Importance for Tectonics and Groundwater Flow. International Journal of Earth Sciences, 94, 580-593. https://doi.org/10.1007/s00531-005-0501-4
[44]
Russell, H., et al. (2011) Three-Dimensional Geological Mapping for Groundwater Applications. In: Berg, R.C., Mathers, S.J., Kessler, H. and Keefer, D.A., Eds., Synopsis of Current Three-Dimensional Geological Mapping and Modeling in Geological Survey Organizations, Illinois State Geological Survey, 92.
[45]
Thomsen, R. (2011) 3D Groundwater Mapping in Denmark Based on Calibreted High Resolution Airborne Geophysical Data. Workshop Extended Abstract, Geological Society of America. https://pub.geus.dk/en/publications/3d-groundwater-mapping-in-denmark-based-on-calibreted-high-resolu
[46]
White (2013) Development of Three-Dimensional Models of Sedimentary Lithologies and Piezometric Levels to Understand Groundwater and Surface Water Flows, Lower Wairau Plain, Marlborough, New Zealand with Web and Smart Phone Access to Model Data. https://www.semanticscholar.org/paper/DEVELOPMENT-OF-THREE-DIMENSIONAL-MODELS-OF-AND-TO-%2C-White/b48be325761c5b0c9569a2e2593bfdc9efd36d9f
[47]
Åberg, S.C., Åberg, A.K. and Korkka-Niemi, K. (2021) Three-Dimensional Hydrostratigraphy and Groundwater Flow Models in Complex Quaternary Deposits and Weathered/Fractured Bedrock: Evaluating Increasing Model Complexity. Hydrogeology Journal, 29, 1043-1074. https://doi.org/10.1007/s10040-020-02299-4
[48]
Voss, C.I. and Souza, W.R. (1987) Variable Density Flow and Solute Transport Simulation of Regional Aquifers Containing a Narrow Freshwater-Saltwater Transition Zone. Water Resources Research, 23, 1851-1866. https://doi.org/10.1029/wr023i010p01851
[49]
Buchanan, S. and Triantafilis, J. (2009) Mapping Water Table Depth Using Geophysical and Environmental Variables. Groundwater, 47, 80-96. https://doi.org/10.1111/j.1745-6584.2008.00490.x
[50]
Rabah, F.K.J., Ghabaye, S.M. and Salha, A.A. (2011) Effect of GIS Interpolation Techniques on the Accuracy of the Spatial Representation of Groundwater Monitoring Data in Gaza Strip. Journal of Environmental Science and Technology, 4, 579-589. https://doi.org/10.3923/jest.2011.579.589
[51]
Caruso, C. and Quarta, F. (1998) Interpolation Methods Comparison. Computers & Mathematics with Applications, 35, 109-126. https://doi.org/10.1016/s0898-1221(98)00101-1
[52]
Webster, R. (2001) Geostatistics for Environmental Scientists. John Wiley & Sons. http://archive.org/details/geostatisticsfor0000webs
[53]
Bouhata, R., Kalla, M. and Driddi, H. (2015) Cartographie de la variabilité spatiale de la salinité du sol dans de la zone endoréique de Gadaine (Nord-Est algérien). Romanian Journal of Geography, 59, 63-69.
[54]
Collins, F.C. and Bolstad, P.V. (1996) A Comparison of Spatial Interpolation Techniques in Temperature Estimation. Proceedings of the Third International Conference/Workshop on Integrating GIS and Environmental Modeling, Santa Fe, 21-25 January 1996.
[55]
Johnston, K., Krivoruchko, K. and Lucas, N. (2004) Using ArcGIS Geostatistical Analyst. ESRI, 300.
[56]
Nalder, I.A. and Wein, R.W. (1998) Spatial Interpolation of Climatic Normals: Test of a New Method in the Canadian Boreal Forest. Agricultural and Forest Meteorology, 92, 211-225. https://doi.org/10.1016/s0168-1923(98)00102-6
[57]
Akramkhanov, A., Martius, C., Park, S.J. and Hendrickx, J.M.H. (2011) Environmental Factors of Spatial Distribution of Soil Salinity on Flat Irrigated Terrain. Geoderma, 163, 55-62. https://doi.org/10.1016/j.geoderma.2011.04.001
[58]
Pyrcz, M. and Deutsch, C. (2003) The Whole Story on the Hole Effect. Geostatistical Association of Australasia.
[59]
Delhomme, J.P. (1978) Kriging in the Hydrosciences. Advances in Water Resources, 1, 251-266. https://doi.org/10.1016/0309-1708(78)90039-8
[60]
ESRI (2025) Utilisation de la validation croisée pour évaluer les résultats d’interpolation. https://pro.arcgis.com/fr/pro-app/3.3/help/analysis/geostatistical-analyst/performing-cross-validation-and-validation.htm
[61]
Triki Fourati, H., Bouaziz, M., Benzina, M. and Bouaziz, S. (2017) Detection of Terrain Indices Related to Soil Salinity and Mapping Salt-Affected Soils Using Remote Sensing and Geostatistical Techniques. Environmental Monitoring and Assessment, 189, Article No. 177. https://doi.org/10.1007/s10661-017-5877-7
[62]
Arslan, H. (2012) Spatial and Temporal Mapping of Groundwater Salinity Using Ordinary Kriging and Indicator Kriging: The Case of Bafra Plain, Turkey. Agricultural Water Management, 113, 57-63. https://doi.org/10.1016/j.agwat.2012.06.015
[63]
Tabasaki, K. and Mink, J. (1983) Volcano Feeder Dikes Impound Large Resources of Groundwater in the Hawaîan Island. International Conference on Groundwater and Management, Sydney, 5-9 December 1983, 309-318.
[64]
Lau, L.S. and Mink, J.F. (2006) Hydrology of the Hawaiian Islands. University of Hawaii Press.
[65]
SONEDE (2023) Rapport annuel d’exploitation des eaux souterraines de l’île de la Grande Comore. Société Nationnalle d’Exploitation et de Distribution des Eaux (SONEDE).
