Trends and Changes in Recent and Future Penman-Monteith Potential Evapotranspiration in Benin (West Africa)

Abstract

In this study, the recent variability of the annual potential evapotranspiration (PET) of six synoptic stations of Benin was carried out. The future changes of PET under RCP4.5 and RCP8.5 scenarios were also quantified under three different projected periods (P1 = 2011–2040, P2 = 2041–2070 and P3 = 2071–2100) compared to the reference period (1981–2010). The results show a high variability of PET at all stations over the baseline period with alternating of deficit and excess periods. The Representative Concentration Pathways (RCP4.5 and RCP8.5) scenarios indicate that annual PET gradually increase and reach its maximum on 2100. However, PET’s changes from the two forcing scenarios start to diverge only around 2070 and this divergence is maximal on 2100. The rates of changes related to the baseline period vary from 2 to 7% for P1 and both scenarios, 5 to 10% for P2 and both scenarios, 7 to 12% for P3 and RCP4.5 scenario and 15 to 20% for P3 and RCP8.5 scenario. At seasonal scale, the results show a progressive increase (from 15 to 25% related to the baseline period) of PET until 2100 for January, February, June, July and December. In April, May, August, September and October, there is a slight decrease (from −5 to 0%) of PET according to RCP4.5 scenario while there is a slight increase (0 to 5%) for RCP8.5 scenario.