Quantifying the Relative Contribution of the Climate and Direct Human Impacts on Mean Annual Streamflow in Catchment Bandama (Côte d’Ivoire)

N’Guessan Kouamé Emmanuel ABO¹, Emile Gneneyougo SORO¹ and Blé Anouma Fhorest YAO^1,

¹Geosciences and Environment Laboratory, Training and Research Unit in Environmental Science and Management, Nangui Abrogoua University, Abidjan, Côte d’Ivoire

Cite this paper:
N’Guessan Kouamé Emmanuel ABO, Emile Gneneyougo SORO and Blé Anouma Fhorest YAO. Quantifying the Relative Contribution of the Climate and Direct Human Impacts on Mean Annual Streamflow in Catchment Bandama (Côte d’Ivoire). American Journal of Water Resources. 2025; 13(5):170-176. doi: 10.12691/ajwr-13-5-1

Abstract

This study assesses the hydrological dynamics of the Bandama River Basin in Côte d’Ivoire under increasing climatic and anthropogenic pressures. Hydroclimatic series (1950–2020) of rainfall, temperature, evapotranspiration, and discharge were analyzed using statistical tests (cumulative deviation, Kruskal–Wallis, Mann–Kendall, SNHT) to identify breakpoints, trends, and spatio-temporal variability. The results reveal strong interannual variability of river discharge (CV = 74.5%) compared to rainfall (CV = 14.3%) and potential Evapotranspiration (PET) (CV = 5.5%). Significant hydro-climatic breakpoints were detected around 1970–1976 and 1994. The assessment of relative contributions using the climate elasticity method and Budyko decomposition shows the predominance of human activities (75–79%) over climatic factors (21–24%) in explaining mean discharge variations at Tiassalé. These findings highlight that the proliferation of dams, agricultural expansion, deforestation, and urbanization are now the main drivers of hydrological alterations, outweighing the effect of climate. The study provides scientific references to support sustainable and integrated water resources management in the Bandama Basin.

Keywords:
Bandama Basin hydroclimatic variability streamflow anthropogenic factors Budyko climate elasticity

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References:

[1]	IPCC (2021). Sixth Assessment Report: Climate Change 2021. The Physical Science Basis. Cambridge University Press.
[2]	Ali, A., Lebel, T., & Amani, A. (2019). Rainfall variability, floods and droughts in the Sahel: recent trends and future projections. Climate Dynamics, 52(3–4), 1095–1113.
[3]	Dottori, F., Szewczyk, W., Ciscar, J. C., Zhao, F., Alfieri, L., Hirabayashi, Y., ... & Feyen, L. (2018). Increased human and economic losses from river flooding with anthropogenic warming. Nature Climate Change, 8(9), 781–786.
[4]	Tan, X., Liu, B., & Chen, J. (2020). Relative contributions of climate change and human activities to runoff variation: A review. Stochastic Environmental Research and Risk Assessment, 34, 1541–1556.
[5]	Zhai, R., Wang, G., & Liu, J. (2016). Runoff response to climate change and human activities in typical catchments of the Loess Plateau, China. Hydrology Research, 47(6), 1166–1181.
[6]	Xia, H., Su, Y., Yang, L., Feng, Q., Liu, W., & Ma, J. (2024). Effects of climate change and human activities on streamflow in arid alpine water source regions: A case study of the Shiyang River, China. Land, 13(11), 1961.
[7]	Goula B. T. A., Savane I., Konan B., Fadika V. et Kouadio G. B. (2006). Impact de la variabilité climatique sur les ressources hydriques des bassins de N’Zo et N’Zi en Côte d’Ivoire (Afrique tropicale humide), VertigO, 1.
[8]	Saley M. B. & Savané I. (2009). Impacts du changement climatique sur les ressources en eau en zone tropicale humide: cas du bassin versant du Bandama en Côte d’Ivoire. Agronomie Africaine, 21 (1), 1-11p.
[9]	Kouassi A. M., Kouamé K. F., Koffi Y. B., Goula B. T. A., Lasm T., Paturel J. E. et Biemi J. (2008). Influence de la variabilité climatique et de la modification de l’occupation du sol sur la relation pluie-débit à partir d’une modélisation globale du bassin versant du N’Zi (Bandama) en Côte d’Ivoire. Revue Ivoirienne des Sciences et Technologie: 207 – 229.
[10]	Kouassi A. M., Kouamé K. F., Koffi Y. B., Djè K. B., Paturel J. E. et Oularé 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. Cybergéo: European Journal of Geography, Environment, Nature, Paysage, 513: 29.
[11]	Kouassi A. M., Assoko A. V. S., Djè K. B., Kouakou K. E., Kouamé K. F. et Biemi J. (2017). Analysis of the persistence of drought in West Africa: Characterization of the recent climate variability in Ivory Coast. Environmental and Water Sciences, Public Health et Territorial Intelligence, 2: 47-59.
[12]	Kamagaté A., Koffi Y. B., Kouassi A. M., Kouakou B.D., et Seydou D. (2019). Impacts des Évolutions Climatiques sur les Ressources en eau des Petits Bassins en Afrique Sub-Saharienne: Application au bassin versant du Bandama à Tortiya (Nord Côte d’Ivoire). European Scientific Journal, ESJ, 15 (9), 84.
[13]	FAO (1996). Etat des connaissances sur les pêcheries continentales ivoiriennes. Rapport de consultation, avril 1996. Rome: Organisation des Nations Unies pour l’alimentation et l’agriculture (FAO), 52 p.
[14]	SORO, T. D., BLE, L. O., KOUA, T. J.-J., ADJIRI, O. A., AHOUSSI, K. E., SORO, G., OGA Y.M-S. SORO, N. (2022). Suivi de la dynamique de l’occupation et de l’utilisation du sol dans le bassin versant du Haut Bandama à Tortiya (Nord de la Côte d’Ivoire) et son impact sur les écoulements. Environmental and Water Sciences, Public Health and Territorial Intelligence Journal, 6(1), 754–760.
[15]	Torabi H., Darabi H., Shahedi K., Solaimani K., Klove B. et al. (2020). Une approche basée sur des scénarii pour évaluer les impacts hydrologiques de l’utilisation des terres et du changement climatique dans le bassin versant de Marboreb, Iran. Journal of Hydrology, Modélisation et évaluation environnemental, 25:41 – 57.
[16]	Zhang L., Chen X., Huang B., Chen L. et Liu J. (2024). Attribution de la variation du ruissellement dans la zone de construction du réservoir: basée sur un modèle d’apprentissage profond fusionné et le cadre Budyko. Atmosphère, 15 (2):164.
[17]	Lévêque C., Dejoux C. et Iltis A. (1983). Limnologie du fleuve Bandama, Côte d’Ivoire. Hydrobiologia, 100: 113-141.
[18]	Naorem N. et Devi T. K. (2014). Estimation of potential evapotranspiration using empirical models for Imphal. International Journal of Innovative Technology and Exploring Engineering (IJITEE), 4 (7):119 – 123.
[19]	Chow & Mays, 1988.
[20]	Schauber, S., & Nouns, Z. M. (2010). Using the cumulative deviation method for cross-institutional benchmarking in the Berlin progress test. Medical Teacher, 32(6), 471–475.
[21]	Chan, Y., & Walmsley, R. P. (1997). Learning and understanding the Kruskal–Wallis one‐way analysis‐of‐variance‐by‐ranks test for differences among three or more independent groups. Physical Therapy, 77(12), 1755–1762.
[22]	Schaake J. C. (1990). From climate to flow. In Climate Change and US Water Resources: 177–206.
[23]	Zhang L., Dawes W. R. et Walker G. R. (2001). Response of mean annual evapotranspiration to vegetation changes at catchment scale. Water Resources Research, 37(3): 701-708.
[24]	Koster R. D. et Suarez M. J. (1999). A simple framework for examining the interannual variability of land surface moisture fluxes. Journal of Climate, 12: 1911–1917.
[25]	Zheng H., Lu Z., Zhu R., Liu C., Sato Y. et Fukushima Y. (2009). Responses of streamflow to climate and land surface change in the headwaters of the Yellow River Basin. Water Resources Research, 45: 641–648.
[26]	Xia J., Zeng S., Du H. et Zhang C. (2014). Quantifying the effects of climate change and human activities on runoff in the water source area of Beijing, China. Hydrological Sciences Journal, 59 (10):1794 -1807.
[27]	Gbohoui Y. P. (2021). Modélisation hydrologique de bassins emboîtés du Nakanbé au Burkina Faso dans un contexte de changement global, Thèse de doctorat à l’Institut International d’Ingénierie de l’Eau et de l’Environnement (2iE), Ouagadougou, Burkina Faso, 292 p.
[28]	Wang D, Hejazi M. 2011. Quantifying the relative contribution of the climate and direct human impacts on mean annual streamflow in the contiguous United States. Water Resources Research 47 (10).
[29]	Berghuijs W., Wouter R., Sebastian J. et Gnann R. A. W. (2020). Unanswered questions on the Budyko framework. Hydrological Processes, 265: 164 – 177.
[30]	Fu B. P. (1981). On the calculation of the evaporation from land surface (in Chinese). Scientia Atmospherica Sinica, 5: 23 – 31.
[31]	Brou Y. T. (2005). Climat, mutations socio-économiques et paysages en Côte d’Ivoire. Mémoire de l’Habilitation à Diriger des Recherches, Université des Sciences et Technologies de Lille, France, 212 p.
[32]	Zhao G., Tian P. Mu X., Jiao J., Wang F. et Gao P. (2014). Quantifying the impact of climate variability and human activities on streamflow in the middle reaches of the yellow River basin, China. Journal of Hydrology, 519, pp. 387 – 398.
[33]	Viel V., Delahaye D. et Reulier R. (2014). "Impact de l’organisation des structures paysagères sur les dynamiques de ruissellement de surface en domaine bocager. Etude comparée de trois petits bassin s versants bas-normands", Géomorphologie, 2, pp. 175-188.