Abstract:
Drought and Flood episodes are twin issues that are consequences of extreme rainfall events. The
negative impact of extreme rainfall events makes understanding their behaviour under the future climate
change necessary for regional planning. Hence, the objective of the study is to project extreme rainfall
indices in Guinea and Sudano-Sahelian ecological zones, Nigeria. A set of four extreme rainfall indices
namely: maximum 5-day rainfall (Rx5day), heavy rainfall days (R10mm), consecutive wet days (CWD)
and consecutive dry days (CDD) were adopted. The data and computation were done using KNMI
Climate Explorer. Projections were produced for the near-term 2019-2048, mid-term 2049-2078 and
long-term 2079-2100 periods with reference to the 1959-1988 and 1989-2018 baselines. The multi-model
ensemble mean of couple model intercomparison project 5 (CMIP5) under representative concentration
pathways (RCPs) 2.6, 4.5, and 8.5 were used. Mann-Kendal statistical test was adopted to analyze the
trends in extreme rainfall indices at the 0.05 significance level. Based on the results, it can be deduced
that there is a significant positive trend in the whole Guinea and Sudano-Sahelian ecological zone as a
region for maximum 5-day rainfall with respect to all the three RCPs. As for heavy rainfall, itreveals that
there is no significant positive trend for RCP2.6 with respect to the three projected periods under
consideration but significant positive trends with respect to 2049-2078 for RCP4.5 as well as RCP8.5
with respect to 2049-2078 and 2079-2100 periods. Increase in CDD, as well as a decrease in CWD, were
both not significant at the 0.05 confidence level. Therefore, it is expected that this study will aid guidance
to the understanding of the ongoing changes as well as possible changes in rainfall and rainfall-related
extremes. It is also important for future planning of water resources management and agriculture in
Guinea and Sudano-Sahelian ecological zones of Nigeria.
