The Sequence of Wet and Dry Days at Ibadan and Onne (Sub-Humid Zone of Nigeria)

Abstract

Twenty-three years daily rainfall data were collected for Ibadan while twenty years data were collected for Onne. These data were analysed and modelled for the dependence of wet days following dry days; dry days following wet days; dry days following dry days and wet days following wet days using the first order Markov chain rule. The results were produced as monthly and decadal transition probability of dry days, wet days and their dependence, and this was used to model the dependence of wet and dry days in the study area. This model was tested using Ten years daily rainfall record each of Akure and Calabar for the sub-humid and humid areas and was found to perform well in its predictability. The study shows that, for the purpose of water resources planning as well as agriculture operations in the two area under study and for most humid and sub-humid stations, there is need to take into consideration the state (i.e. wetness or dryness) of the previous 2 day especially in the rainy months.