Characterisation of rainfall pattern in northern Nigeria

Abstract

In this work, attempt was made to characterise rainfall pattern in Northern Nigeria. Investigations were carried out by using rainfall data from selected gauging stations across the hydrological areas; Three statistical tests: (i) statistical moment (ii) Analytic studies of annual  rainfall cycles and (iii) detection of drought signature via standardised anomaly were explored for this analysis. The results obtained  indicated that most observed stations showed significant pattern in the series. For instance, rainfall statistical moment portrayed that HA  1 has a mean annual rainfall of 194cm with standard deviation of 16.79cm and HA 3 and HA 8 jostled for the less for example HA 3 had  annual mean rainfall of 76.207cm and substantial standard deviation that stood at 21.598cm which is quit debilitating whereas HA 8  scored the least mean, that is 36.175cm and outrageous standard deviation of 24.700cm. In this context, incidence of rainfall seems to  decreases with a sequential increment of latitudinal signatory. In addition, notable years of extreme dryness are 1976, 1978,1983,1984,  1986, 1987, 1972, 1973,1974 and 1976 and this probably informed the classification of the whole Northern Nigeria as a slightly dry region  when considered in the period understudy. In addition, general pattern for the entire HAs shown that for the period under consideration  the rainfall increasing at an average rate of 6.10% per annum for whole Northern Nigeria, a factors sufficient to sustain rain fed agriculture. Considering the results obtained, there is need to examine other hydrometeorology variables in addition to rainfall in order  to have a thorough understanding of the time-space dependent behaviour of the hydro-meteorological processes and their correlating  aggregate effects. It is pertinent therefore that several statistical approaches should be used to capture trend and mutations; as one approach may not truly give a snapshot of` hydrological variability in a particular basin; i.e., for purposes of drawing effective conclusions.