Calibration of the hydrological model GR4J from potential evapotranspiration estimates by the Penman-Monteith and Oudin methods in the Ouémé watershed (West Africa) Hydrological processes and water security in a changing world Kodja, D.J. Akognongbé, A.J.S. Amoussou, E. /Mahé, Gil Vissin, E.W. /Paturel, Jean-Emmanuel Houndénou, C. MODELE HYDROLOGIQUE CALIBRAGE ETALONNAGE EVAPOTRANSPIRATION POTENTIELLE ESTIMATION INONDATION SECHERESSE PRECIPITATION VARIATION JOURNALIERE DEBIT BASSIN VERSANT 1971 2010 MODELE GR4J EQUATION PENMAN-MONTEITH METHODE OUDIN The Ouémé watersheds at Bétérou and Bonou has been recently facing increased sensitivity to extreme hydroclimatic phenomena that occurred by flooding or drought events. In the same time, the population growth and the related socio-economic activities increased the pressure state on water resources. In this context, hydrological modeling is an important issue and this study aims at analyzing the calibration of the hydrological model GR4J based on PET Penman-Monteith and Oudin methods. Daily rainfall, Penman-Monteith and Oudin evapotranspiration and daily data flow from the Bétérou and Bonou hydrometric stations on the Ouémé Basin have been implemented in the GR4J model over the period 1971 to 2010. Oudin PET values are slightly higher than the Penman-Monteith PET ones. However, the difference between the two PET methods have only few impacts on the optimization and performance criteria of the GR4J model. The Nash values ranges from 0.83 to 0.91 in Bonou, and 0.52 to 0.70 in Bétérou for the calibration in dry period, while in validation, they are 0.59 to 0.78 in Bétérou, and 0.56 to 0.88 in Bonou in wet season. In view of these results, with the two PET methods used which do not result from the same climatic variables, it should be said that the formulation of PET has only few impacts on the results of GR4J for these tropical basins. AISH Yu, Z. (ed.) Lu, C. (ed.) Yu, D.D. (ed.) Cai, J. (ed.) /Mahé, Gil (ed.) Mishra, A. (ed.) Cudennec, C. (ed.) Van Lanen, H.A.J. (ed.) /Orange, Didier (ed.) Amani. A. (ed.) 2020 text https://www.documentation.ird.fr/hor/fdi:010082893 fdi:010082893 Kodja D.J., Akognongbé A.J.S., Amoussou E., Mahé Gil, Vissin E.W., Paturel Jean-Emmanuel, Houndénou C., . Calibration of the hydrological model GR4J from potential evapotranspiration estimates by the Penman-Monteith and Oudin methods in the Ouémé watershed (West Africa). In : Yu Z. (ed.), Lu C. (ed.), Yu D.D. (ed.), Cai J. (ed.), Mahé Gil (ed.), Mishra A. (ed.), Cudennec C. (ed.), Van Lanen H.A.J. (ed.), Orange Didier (ed.), Amani. A. (ed.), . Hydrological processes and water security in a changing world AISH, ; 383). 2020, 163-169 Global FRIEND-Water Conference : Hydrological Processes and Water security in a Changing World, 8., Pékin (CHN), 2018/11/06-09 EN AFRIQUE DE L'OUEST