Hydroclimatic trends, breakpoints and future projection analysis of the Ogun River Basin in West Africa

Trend analysis is important to understand the performance and features of hydrological variables over a long-time scale. This study analyses the hydroclimatic trends in precipitation, temperature (minimum and maximum) data from seven synoptic stations and river discharge from three outlets that were investigated between 1984–2019 and projected between 2020–2060 over the Ogun River Basin. The results of the trend analysis showed a non-significant positive trend in precipitation and a significant positive trend (p,0.05 and p,0.01 significant trends) in maximum and minimum temperatures. The discharge reveals a non-significant positive trend on the annual scale while a significant decreasing trend in the dry season. The annual rainfall projection is expected to increase by 1.3% under RCP 2.6 and 1.4% under RCP 8.5 by 2060. The mean annual temperature is expected to increase between 1.5-2.5 °C under RCP 2.6 and 2-3.5 °C under RCP 8.5 by 2060, respectively. The variations in discharge without significant changes in rainfall suggested other variables were influencing the discharge. These could be changes in river basin physical elements such as alterations in the dynamics of land use land cover changes. The findings of this study can be used for strategizing adaptation and mitigation measures for water resources management. HIGHLIGHTS To explore seasonal trends.; Impacts of climate change on the discharge.; Effects of temperature on the streamflow.; Impact of low discharge on water resources.; Effects of anthropogenic activities on water resources management.;