Analysis of Rainfall Trends and Water Balance Characteristics of Southern Borno Northeast Nigeria

Abstract

This study analyzes the trend of rainfall in Southern Borno and in doing that the cumulative index analysis of Walter (1967) was used to calculate onset, cessation and length of rainy days. The result showed that generally, the onset of rainfall is between the months of May and June while cessation is mainly October and average rainy days of 129 days. Thornthwaite and Mather model was used to calculate water budget of the study area. The result showed average monthly PET of 10.182 mm for the period of study, with total average PET of 122.188, the month with the highest PET is April, with a value of 18.783 and the month with the lowest PET is August with a value of 5.337. The weighted average annual deficit in rain water for the study area is 8.429 mm3 and the annual surplus is 138.578 mm. The result also showed that the area has on the average, five months of WD from November to March, while the remaining months have zero (0) values of water deficit. WS ranging from April to October, while the remaining months have zero values of WS.