Spatial-Temporal Variation and Prediction of Rainfall in Northeastern Nigeria

Umar Bibi,Jörg Kaduk,Heiko Balzter

doi:10.3390/cli2030206

Umar Bibi, Jörg Kaduk + Show 1 more

Open Access

https://doi.org/10.3390/cli2030206

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Journal: Climate	Publication Date: Sep 17, 2014
Citations: 45	License type: CC BY 4.0

Affiliation: University of Leicester, Adamawa State University

Abstract

In Northeastern Nigeria seasonal rainfall is critical for the availability of water for domestic use through surface and sub-surface recharge and agricultural production, which is mostly rain fed. Variability in rainfall over the last 60 years is the main cause for crop failure and water scarcity in the region, particularly, due to late onset of rainfall, short dry spells and multi-annual droughts. In this study, we analyze 27 years (1980–2006) of gridded daily rainfall data obtained from a merged dataset by the National Centre for Environmental Prediction and Climate Research Unit reanalysis data (NCEP-CRU) for spatial-temporal variability of monthly amounts and frequency in rainfall and rainfall trends. Temporal variability was assessed using the percentage coefficient of variation and temporal trends in rainfall were assessed using maps of linear regression slopes for the months of May through October. These six months cover the period of the onset and cessation of the wet season throughout the region. Monthly rainfall amount and frequency were then predicted over a 24-month period using the Auto Regressive Integrated Moving Average (ARIMA) Model. The predictions were evaluated using NCEP-CRU data for the same period. Kolmogorov Smirnov test results suggest that despite there are some months during the wet season (May–October) when there is no significant agreement (p < 0.05) between the monthly distribution of the values of the model and the corresponding 24-month NCEP-CRU data, the model did better than simply replicating the long term mean of the data used for the prediction. Overall, the model does well in areas and months with lower temporal rainfall variability. Maps of the coefficient of variation and regression slopes are presented to indicate areas of high rainfall variability and water deficit over the period under study. The implications of these results for future policies on Agriculture and Water Management in the region are highlighted.

Highlights

In the semi-arid region of Northeastern Nigeria, seasonal rainfall patterns are very important for continuous supply of water for domestic use, because rainfall leads to surface and sub-surface recharge, and for rain-fed agricultural production [1,2,3]
Rainfall in Northeastern Nigeria is controlled by the West African Monsoon (WAM) [6], and each year, during the boreal summer, this air mass dominates the region in response to a low pressure belt developing in North Africa with a parallel high pressure belt existing off the Gulf of Guinea
The CV is lowest in the months at the peak of the wet season (July–August) when the CV is less than 20% for most areas south of latitude 10° north

Summary

Introduction

In the semi-arid region of Northeastern Nigeria, seasonal rainfall patterns are very important for continuous supply of water for domestic use, because rainfall leads to surface and sub-surface recharge, and for rain-fed agricultural production [1,2,3]. Variability in rainfall over the last 60 years has included repeatedly late onset of rainfall, short dry spells, and sometimes droughts lasting several years. These events are the main factors determining crop failure and water scarcity in the region. Once the monsoon has commenced, rainfall events are mostly a product of instability and convection cells developing in the lower atmosphere influenced by the nature and characteristics of the land surface [3]

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