Trends and periodicities of annual rainfall over Ibadan region, Nigeria

Adejuwon, J. O.

doi:10.1002/wwp2.12081

Cited by 5 publications

(3 citation statements)

References 33 publications

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“…drought, Nigeria, Pettit test, rainfall trend, standardized precipitation index of climate variability and change given its prevailing influence on water resource management, agricultural production, and climate change mitigation (Ayalew et al, 2012). Similar studies in West Africa, especially in Nigeria, include Odekunle and Adejuwon (2007), Akinsanola and Ogunjobi (2014), Sanogo et al (2015), Yaya and Fashae (2015), Nkrumah et al (2019), Adejuwon (2022), andAdeyefa (2022). Over West Africa, in terms of some basic geographical factors, Olaniran (1987) examined the distributional pattern of rainfall occurrence in storms of different sizes in Nigeria and related the pattern obtained to three factors.…”

Section: Introductionmentioning

confidence: 93%

Drought assessment and rainfall trend analysis in southwestern Nigeria

2023

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Prolonged instability and insufficiency of rainfall resulting in drought, extreme weather events, and food insecurity are climate change‐related challenges bedeviling humanity. This study assessed drought conditions and rainfall trends in southwestern Nigeria, using the 1984–2014 rainfall dataset from the Nigerian Meteorological Agency (NIMET). The coefficient of variation (CV), long‐term standardized precipitation index (SPI), serial correlation test, Mann–Kendall trend analysis, Sens's slope estimation, and Pettit test were carried out using various R programming packages. Long‐term mean annual rainfall ranged between 1224.7 and 1537.1 mm. The highest variation (17.3%) was observed for Abeokuta and Ikeja. SPI analysis revealed Ibadan and Oshogbo as the driest and wettest stations, respectively. There was no serial autocorrelation in the dataset. The Mann–Kendall trend showed an upward rainfall trend for Abeokuta, Ibadan, and Ikeja and a downward trend for Akure and Oshogbo. Sen's slope annual rates of change in mm for Abeokuta, Akure, Ibadan, Ikeja, and Oshogbo are 6.69, −2.36, 2.07, 7.82, and 1.42 respectively. The Pettit test revealed change points that are not statistically significant. The drought assessment largely showed a cyclical SPI pattern with greater years of dryness. Given the increasing impact of climate change, future studies are needed to simulate the local drivers of drought severity and frequency and the changing rainfall pattern in rapidly urbanizing cities. There is also the need to incorporate climate‐related adaptive strategies in existing water management policies.

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Section: Introductionmentioning

confidence: 93%

Drought assessment and rainfall trend analysis in southwestern Nigeria

2023

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“…The climate of Ogun State exhibits a definite and marked wet season between March and October and a dry season from November to February. The mT dominates during the wet season whereas the cT air mass predominates during the dry season (Adejuwon, 2022). The rainfall is double maxima in character.…”

Section: The Study Areamentioning

confidence: 99%

Physicochemical characteristics and heavy metals of groundwater during the wet and dry seasons at the Lafarge cement factory environment, Sagamu, Ogun State, Nigeria

Adejuwon

Odusote

2023

World Water Policy

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This study examined the physical, chemical, and heavy metals in groundwater from boreholes and hand‐dug wells at the Lafarge cement factory environment at Sagamu, Ogun State, Nigeria. Water samples were obtained from 20 sampling locations during the wet and dry seasons of 2019. The 17 parameters determined include the pH, temperature, electrical conductivity, total dissolved solids (TDS), total hardness, alkalinity, salinity, chloride, sulfate, phosphate, nitrate, calcium, magnesium, copper, lead, iron, and cadmium. The samples were analyzed using titrimetric and spectrophotometric methods. Correlation analysis was applied as part of the analytical tool in this study. The result indicated low physiochemical concentration of pH, total hardness, sulfate, nitrate, chloride, magnesium, calcium (>1% to 15%), and electrical conductivity (>1000 μS/cm) and fell within the Standard Organization of Nigeria (SON) and World Health Organization (WHO) desirable and maximum permissible limits for potable water during the wet and dry seasons. However, phosphate was above the standard limit for portable water of 6.5 mg/L in all sampling locations, whereas the total alkalinity was above the WHO standard limit (200 mg/L) in 12 locations in the wet seasons and a location in the dry season. Salinity was also above standards in one and four locations in the wet and dry seasons, respectively. Lead and cadmium were not detected in most locations, whereas iron, lead, cadmium, and copper were above standard limits in some locations. A significant relationship exists between the heavy metals and some of the physiochemical parameters at p ≥ .05 and p ≥ .01. The polluted water in most locations is capable of resulting in an adverse health hazard. Thus, this study explains the effect of physicochemical and heavy metals on water management at Sagamu and is important for water resource planning.

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“…The Kendall tau correlation was preferred to other statistical analyses including the Spearman (rho) rank correlation, the Pearson's correlation, and the linear regression. Though there does not seem to be a clear advantage in using the Kendall tau correlation over the Spearman (rho) rank correlation, as the two measures align closely and lead to the same inferences most of the time (Adejuwon, 2022), the Kendall tau correlation distribution has better statistical properties; and the interpretation of Kendall's tau in terms of the probabilities of observing the concordant and discordant pairs is very direct (Hauke & Kossowski, 2011; Kasirajan, 2020). The Kendall tau correlation has smaller gross error sensitivity and smaller asymptotic variance.…”

Section: Data Collection and Analysismentioning

confidence: 99%

Rainfall extremes and trends during the little dry season in Nigeria

Adejuwon

2023

World Water Policy

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The little dry season (LDS), a phenomenon of interest in West Africa is associated with a dry spell amid the wet season and is consequential to agriculture and global food production. However, the current literature suffers a knowledge gap on rainfall extremes and trends during this period. This study examined the rainfall extremes and trends during the LDS in Nigeria using daily and monthly rainfall data from 19 synoptic stations for the period 1960 to 2020. The Kendal tau correlation, Standardized Precipitation Index (SPI), and descriptive statistics were employed for the study. The result showed the LDS reduction from the western area eastward and northward. The LDS is more intense in August than in July and is characterized by drought, ranging from mild (74.34%) to extreme (2.64%). The droughts fluctuate with wet conditions. The severe and extreme drought was mostly confined to the southwestern area. Lagos observed the highest drought occurrences, 50% of below 10‐mm rainfall and prolonged dry spells. Shaki recorded 13.73% of the total severe droughts while Osogbo recorded 43.33% of extreme drought events. The mean SPI is majorly distributed in space as mild drought and mildly wet respectively, except for a few stations where it ranged from moderate to extreme. A significant trend was negative at Bida (p ≤ .01), positive at Iseyin (p ≤ .05), Abeokuta (p ≤ .01), and Akure (p ≤ .01) in July, and Bida (p ≤ .05) in August. The LDS period is associated with hardship through prolonged dry spells and drought. This study explains the extreme rainfall and trends during the LDS to water management and suggests agricultural planning, forecasting, and mitigation of drought impacts.

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Trends and periodicities of annual rainfall over Ibadan region, Nigeria

Cited by 5 publications

References 33 publications

Drought assessment and rainfall trend analysis in southwestern Nigeria

Drought assessment and rainfall trend analysis in southwestern Nigeria

Physicochemical characteristics and heavy metals of groundwater during the wet and dry seasons at the Lafarge cement factory environment, Sagamu, Ogun State, Nigeria

Rainfall extremes and trends during the little dry season in Nigeria

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