Rainfall Variability in Western Côte d’Ivoire: A Case Study of the Mountain District (1961–2020)

COULIBALY Léréyaha^1, , OUATTARA Ismaïla¹, YAO Kouadio Assemien François¹, OUEDRAOGO Moussa¹, DIALLO Seydou DAO Amidou², SORO Gneneyougo Emile² and KAMAGATE Bamory²

¹Department of Mines and Reservoirs, Training and Research Unit in Geological and Mining Sciences, University of Man, Man; Côte d'Ivoire

²Geosciences and Environment Laboratory, Training and Research Unit in Environmental Sciences and Management, Nangui Abrogoua University, Abidjan, Côte d'Ivoire

Cite this paper:
COULIBALY Léréyaha, OUATTARA Ismaïla, YAO Kouadio Assemien François, OUEDRAOGO Moussa, DIALLO Seydou DAO Amidou, SORO Gneneyougo Emile and KAMAGATE Bamory. Rainfall Variability in Western Côte d’Ivoire: A Case Study of the Mountain District (1961–2020). American Journal of Water Resources. 2025; 13(4):121-128. doi: 10.12691/ajwr-13-4-1

Abstract

This study investigates the variability of climatic parameters, specifically rainfall, in the Mountain District of Côte d’Ivoire. It utilizes satellite-based rainfall data spanning from 1961 to 2020, complemented by observational data from SIEREM (Système d'Informations Environnementales sur les Ressources en Eau et leur Modélisation) database for the period 1961–2000. A preliminary processing of the rainfall datasets was conducted to correct biases and address data gaps. The methodological framework combines statistical change-point detection tests (Cusum (Cummulative Sum) and Student’s t-test) with trend analysis techniques (Mann-Kendall and linear regression). Results from the change-point tests indicate no statistically significant discontinuities in the rainfall time series. However, trend analyses suggest a non-significant overall decline in precipitation across all monitoring stations. Notably, a marked reduction in monthly rainfall totals during May and June was observed, potentially offset by increased precipitation from August to October. Decadal analysis of annual cumulative rainfall over six decades reveals that precipitation consistently exceeded 1,000 mm, except at the Kouibly and Semien stations, where totals ranged from 922 mm to 981 mm during the decades 1971–1980, 1991–2000, and 2011–2020. Spatial analysis of rainfall isohyets highlights a heterogeneous distribution across the district, with rainfall patterns exhibiting an East–West gradient.

Keywords:
rainfall variability mountain regions precipitation trends Côte d’Ivoire

This work is licensed under a Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

References:

[1]	Servat, E., Paturel, J. E., Kouamé, B., Travaglio, M., Ouedraogo, M., Boyer, J. F., Lubès-Niel, H., Fritsch, J. M., Masson, J. M., & Marieu, B. (1998). Identification, caractérisation et conséquences d'une variabilité hydrologique en Afrique de l'Ouest et Centrale. IAHS Journal, 252, 323–337.
[2]	Danumah, J. H., Odai, S. N., Saley, B. M., Szarzynski, J., Adjei, K., Kouamé, F. K., & Akpa, L. Y. (2016). Flood risk assessment and mapping in Abidjan district using multi-criteria analysis (AHP) model and geoinformation techniques (Côte d’Ivoire). Geoenvironmental Disasters, 3(10), 1–13.
[3]	Yao, A. B., Goula, B. T. A., Kouadio, Z. A., Kouakou, K. E., Kane, A., & Sambou, S. (2012). Analysis of Climate Variability and Quantification of Water Resources in the Humid Tropical Area: The Case of the Lobo Watershed in West-Central Côte d’Ivoire. Ivorian Journal of Science and Technology, 19, 136–157.
[4]	Kouao, J.-M., Tagnon, B., Koffi, B., Kouassi, A. M., Kouassi, K. A., & Gone, D. L. (2024). Variabilité climatique et tendances interannuelles récentes du climat en Afrique de l’Ouest : Cas de la Côte d’Ivoire. European Scientific Journal (ESJ), 34, 235.
[5]	Bigot, S., Brou, T., & Servat, E. (2005). Variabilité pluviométrique et relations avec les indices climatiques en Afrique de l’Ouest : cas de la Côte d’Ivoire. Sécheresse, 16(1), 5–13.
[6]	Kouassi, K. H., Kouadio, K. K., Koffi, B. Y., & Boko, M. (2018). Rainfall Variability and Extreme Events in Côte d’Ivoire from 1961 to 2015. Climate, 6(2), 37.
[7]	Kouadio, K. K., Koné, D., Kouassi, K. H., & Aman, A. (2021). Assessment of Climate Variability and Droughts in Côte d’Ivoire Using Standardized Indices. Theoretical and Applied Climatology, 146, 1031–1047.
[8]	Bérenger, K., Alexis, L. B., Kouamé, J. O. K., Valentin, B. E., Konan, J. Y. N., Gnibga, I. Y., Konaté, Y., Dibi, B., & Kouakou, L. K. (2023). Impact of climate and land use/land cover change on Lobo reservoir inflow, West-Central of Côte d'Ivoire. Journal of Hydrology: Regional Studies, 47.
[9]	Abatzoglou, J. T., Dobrowski, S. Z., Parks, S. A., & Hegewisch, K. C. (2018). TerraClimate, a high-resolution global dataset of monthly climate and climatic water balance from 1958–2015. Scientific Data.
[10]	Helsel, D. R., & Hirsch, R. M. (2002). Statistical methods in water resources—Hydrologic analysis and interpretation. Techniques of Water-Resources Investigations of the U.S. Geological Survey, Chap. A3, Book 4, 266–274.
[11]	Templ, M., Alfons, A., & Filzmoser, P. (2012). Exploring incomplete data using visualization tools. Journal of Advances in Data Analysis and Classification, [Online First].
[12]	Lemaître, F. (2002). Recensement des tests de détection de tendances ou de ruptures adaptés à l’analyse de stationnarité des régimes de crues en France. Rapport de fin d’étude TPE, CEMAGREF, 94 p.
[13]	Krishna, U. (2012). Studies in low and flood flow estimation for Irish River Catchments. PhD Thesis, National University of Ireland, Galway, 312 p.
[14]	Sen, P. K. (1968). Estimates of the regression coefficient based on Kendall’s tau. Journal of the American Statistical Association, 63(324), 1379–1389.
[15]	Pingale, S. M., Jat, M. K., Goyal, R. K., & Khare, D. (2014). Spatial and temporal variation of rainfall in semi-arid region of Madhya Pradesh, India. Theoretical and Applied Climatology, 115(3–4), 503–516.
[16]	Savané, I. (1997). Contribution à l'étude géologique et hydrogéologique des aquifères discontinus du socle cristallin d'Odienné (Nord-Ouest de la Côte d’Ivoire). Thèse de doctorat ès Sciences Naturelles, Université d’Abidjan, Côte d’Ivoire, 386 p.
[17]	Brou, Y. T. (1997). Analyse et dynamique de la pluviométrie dans le sud forestier ivoirien : recherche de corrélations entre les variables climatiques et les variables liées aux activités anthropiques. Thèse de Doctorat en Géographie, Université de Cocody, Abidjan, Côte d’Ivoire, 211 p.
[18]	Lasm, T., Kouamé, F., Soro, N., Jourda, J. P. R., & Biémi, J. (2004). Analyse géostatistique de la fracturation extraite de l'imagerie spatiale aéroportée et satellitaire. Application à la région de Man-Danané (Ouest de la Côte d'Ivoire). Revue Ivoirienne des Sciences et Technologie, 5, 135–154.
[19]	Yiou, P., Goubanova, K., Li, Z. X., & Nogaj, M. (2008). Weather regime dependence of extreme value statistics for summer temperature and precipitation. Nonlinear Processes in Geophysics, 15, 365–378.
[20]	Kouassi, A. M., Kouamé, K. F., Koffi, Y. B., Dje, K. B., Paturel, J. E., & Oulare, S. (2010). Analyse de la variabilité climatique et de ses influences sur les régimes pluviométriques saisonniers en Afrique de l’Ouest : cas du bassin versant du N’zi (Bandama) en Côte d’Ivoire. Journals Open Edition, 138, 10400–23388.
[21]	Chatelain, C., Gautier, L., & Spichiger, R. (1996). Forest history fragmentation in southern Côte d'Ivoire. Biodiversity and Conservation, 5, 37–53.
[22]	Ahoussi, K. E., Koffi, Y. B., Kouassi, A. M., Soro, G., Soro, N., & Biémi, J. (2013). Étude de la variabilité hydroclimatique et de ses conséquences sur les ressources en eau du Sud forestier et agricole de la Côte d'Ivoire: cas de la région d'Abidjan-Agboville. International Journal of Pure & Applied Bioscience, 1(6), 30–50.
[23]	Noufé, D., Lidon, B., Mahé, G., Servat, E., & Chaléard, J. L. (2015). Impact de l’évolution des conditions agroclimatiques sur les systèmes de culture à base de banane plantain : le cas de l’Est ivoirien. VertigO – la revue électronique en sciences de l’environnement, 15(1), 1–15.
[24]	Aké-Assi, L. (1998). Impact de l’exploitation forestière et du développement agricole sur la conservation de la diversité biologique en Côte d’Ivoire. Le Flamboyant, 48, 85–87.
[25]	Ruf, F., & Schroth, G. (2004). Chocolate forests and monocultures: a historical review of cocoa growing and its conflicting role in tropical deforestation and forest conservation. In Agroforestry and Biodiversity Conservation in Tropical Landscapes. Island Press, Washington, 6, 107–134.