World Environment 2016, 6(1): 1-9 DOI: 10.5923/j.env.20160601.01 Sarima Modelling and Forecasting of Monthly Rainfall in the Brong Ahafo Region of Ghana Ebenezer Afrifa-Yamoah 1,* , Bashiru I. I. Saeed 2 , Azumah Karim 3 1 Graduate Studies, Kwame Nkrumah Univ. of Science Technology, Kumasi, Ghana 2 Mathematics and Statistics Department, Kumasi Polytechnic, Ghana 3 Al-Huda Islamic School, Kumasi, Ghana Abstract Statistical modelling and data analysis is a crucial instrument in understanding rainfall processes. This article aims at examining the rainfall pattern and fit a suitable model for rainfall prediction in the Brong Ahafo (BA) Region of Ghana. Data from 1975 to 2009 were collected from the Department of Meteorology and Climatology in the BA region. The results revealed that the region experience much rainfall in the months of September and October, and least amount of rainfall in the months of January, December and February. SARIMA (0,0,0)×(1,1,1) 12 , with an AIC score of 8.985894, has been identified as an appropriate model for predicting monthly average rainfall figures for the Brong Ahafo Region of Ghana and hope that when adopted by the Ghana Metrological Agency and other relevant governmental organisations like the National Disaster Management Organisation (NADMO), it will in the long run help in accurate forecasting and education of the populace on rainfall expectancies. Keywords Statistical modelling, Forecast, Decision making, Brong Ahafo, Ghana 1. Introduction Natural resource management is heavily driven by climate. Far reaching impacts of climate change are being felt in ecological, resource-degradation and hydrological process in Ghana. A typical example in Ghana is the constant decrease in the water levels of the Akosombo Hydropower Generation Dam, which is the main source of power generation thus the persistent “dumsor”. The changing climatic conditions have immensely affected rainfall patterns in Ghana, recording downward figures since 1993, which, Kwamena & Benneh (1995) attributed it to the activities of the over 70% citizenry direct or indirect involvement in rain dependencies agriculture. The Forestry Commission of Ghana estimated 8.2 million hectares of forest in 1990 reduced to 1.2 million hectares in 1997 as a result of illegal logging, overgrazing, bad mining practices, industrialization, environmental pollution and urbanization. The irony of the situation is that Ghana is a rain dependent agricultural country. Amidst this background however, flood and rainstorm have been identified under hydro-meteorological disasters in Ghana’s disaster profile for which technical committees have been tasked to develop various hazard maps and to draw education and training programme, emergency preparedness and response plans and advice for the government and * Corresponding author: kingmorose@ymail.com (Afrifa-Yamoah, Ebenezer) Published online at http://journal.sapub.org/env Copyright © 2016 Scientific & Academic Publishing. All Rights Reserved major stakeholders (NADMO, 2015). The BA Region has had its fair share of flood. In 1999, the northern part of BA Region was among the victims of the “northern floods” in which over three thousand persons were affected. The flood re-occurred in 2007 and affected over three hundred thousand (307,127) persons (NADMO, 2015). A major shortfall in disaster management in developing countries, like Ghana, is the limited capacity of responsible agencies to issue correct and up-to-date happenings of events to the populace. This has resulted in deaths and loses of valuable properties that could have been saved. To complement the efforts of these technical committees, resourced materials must be made available. There is the need for appropriate modelling, if possible, of relevant events of life to adequately inform decision making processes, thus the need for this study. Several studies on climatic conditions have been undertaken to understand and identify the changing trend in temperature, rainfall, humility and other related conditions with temperature studies have witnessed consistent agreement in results among researchers (Chin (1977); Coe (1982); Cowpertwait (1994); Chandler (1997); Dunn (2004); Carmona (2005): Beatrice et al (2014); R.C. Noven et al (2015)). However, rainfall studies have resulted in diverse results in same spatial area. A typical case in literature is the study in the Meditarranean, researchers have reported diverse variability patterns (Maheras (1988), Maheras & Vafiaris (1990), Benifo, Orellara & Zunta (1994). In Ghana, climate studies have been conducted and reported in literature. Several attempts have been made by researchers to