Rainfall Distribution in the Upper East Region of Ghana, 1976 – 2016

Abstract

The knowledge and understanding of rainfall distribution of a region are very essential and useful in determining the overall impacts of climate change, especially to the agricultural sector. Monthly rainfall data from 1976-2016 for five selected stations were acquired and subjected to various statistical techniques namely coefficient of variation, 5-year moving average and departure from the mean to obtain the variability and trends in the data. The results showed that the selected stations have uni-modal rainfall distribution and that the rain mostly starts in May and ends in September. High precipitation occurs in July, August and September, with August recording the highest amount with a low variability, indicating the reliable occurrence of precipitation within this period of the year. This is of high importance to farmers and the recharging of aquifers. The wettest station was Zuarungu, with a mean total monthly rainfall of 89.55 mm followed by Navrongo, Bolgatanga, Garu and Manga-Bawku with their respective mean total monthly rainfall as 81.08 mm, 80.59 mm, 79.64 mm and 78.86 mm. High annual variability was found in all the stations and long dry spells were observed from November to March. The rainfall season wet period is between July and September at all the stations and it is recommended that farmers should cultivate early-maturing crops and adopt irrigation farming practices as well as practices which utilize water efficiently.

Understanding Climate Change and Drought Perceptions, Impact and Responses in the Rural Savannah, West Africa

“…An appraisal of available mean annual rainfall data from the Ghana Meteorological Agency for the Zuarungu weather station from 1980-2011, and analysis on rainfall departure from the mean between 1976-2016 [78], corroborate the observations of people and findings regarding the rainfall pattern in the study area. From Figure 2, the data depicts fluctuations in precipitation which mark alternating periods of wet and dry hydrological years in the area.…”

“…In relating these observations to similar findings on the nature of rainfall activity and distribution, specifically for Upper East Region (1976-2016), Ampadu et al [78] (p. 54) have also alluded to high annual variability and prolonged inter-seasonal dry spells for all the stations considered. Besides their observation of the hydrological years of 2013-2015 as the most recent worst dry period with significant departures from the annual mean, they also found that there had generally been a decline in the distribution of rainfall in the study area and entire country over the last four decades [78,79]. The rainfall departures from the annual mean and negative trend recorded in the study region are indicative of drought events during the period.…”

A review of the water resources of Ghana in a changing climate and anthropogenic stresses

“…This trend, they attributed to such anthropogenic activities as deforestation, poor farming practices, overgrazing, harvesting wood for energy, and bushfires. Some other studies (e.g., Ampadu, 2008;Ampadu et al, 2019) were localized and mostly came up with similar conclusions on rainfall, even though some showed some increasing trends. Asante and Amuakwa-Mensah (2015) also projected low rainfall occurrence in 2020, 2050, and 2080, corroborating similar studies.…”

Application of Analytical Hierarchy Process (AHP) and Multi-Criteria Evaluation (MCE) for a Case Study and Scenario Assessment of Flood Risk in the White Volta Basin of the Upper East Region, Ghana

“…Rainfall follows a unimodal pattern [31], with an average annual rainfall of 921mm, ranging from 645mm to 1250mm, creating a growing season lasting approximately 5 to 6 months from April/May to September/October, followed by a long dry and hot season lasting 6 to 7 months from October to April. The annual average temperature ranges from a minimum of 15°C during the dry season (December to February) to a maximum of 45°C in March and April [30].…”