Rainfall characteristics in the humid and transition zones of southwest, Nigeria

Abstract

Rainfall characteristics are important for agriculture since they are the variable constant in rain-fed agriculture. Three important characteristics of rainfall are its amount, frequency and intensity, the values of which vary from place to place, day to day, month to month and also year to year. Precise knowledge of these characteristics is essential for planning the full utilization of rainfall. This study compared rainfall characteristics in the humid zone (Lagos) and transition zones (Abeokuta and Ibadan) in South-Western Nigeria. Daily rainfall data for 26 years (1985-2010) were used to determine the rate of evapotranspiration using the FAO56 Penman-Monteith method for evapotranspiration while dry spells and rain days were
subjected to inferential and descriptive statistics. During the 26years period, the mean rainfall in Abeokuta, Ibadan and Lagos was 1236.77mm, 1418.8mm and 1507mm respectively. Results found that there was no statistically significant difference in amount and incidence of rainfall in Lagos and Ibadan only. On average, dry spell varies from 6-35days with Lagos>Abeokuta>Ibadan while Abeokuta had the mean highest evapotranspiration rate followed by Ibadan and Lagos, during the study period.

Keywords: Mean amount, humid period, climate change, moisture, crop growth