Spatiotemporal Trends in Air Temperature and Their Relationship with Rainfall Erosivity in Parts of Southern Taraba, Northeast Nigeria
Kodak Udemgba Emerson *
Department of Agricultural and Biosystems Engineering, Faculty of Engineering, Federal University Wukari, Taraba State, Nigeria.
Ngozi A. A. Okereke
Department of Agricultural and Biosystems Engineering, Federal University of Technology Owerri, School of Engineering and Engineering Technology, Imo State, Nigeria.
Okore Okay Okorafor
Department of Agricultural and Biosystems Engineering, Federal University of Technology Owerri, School of Engineering and Engineering Technology, Imo State, Nigeria.
Gladys Uche Asonye
Department of Agricultural and Biosystems Engineering, Federal University of Technology Owerri, School of Engineering and Engineering Technology, Imo State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Background: Climate variability can alter air temperature and rainfall characteristics, with important implications for rainfall erosivity and associated soil degradation. However, the relationship between long-term temperature trends and rainfall erosivity remains insufficiently documented in southern Taraba State, Nigeria, limiting location-specific understanding of changing hydro-climatic conditions and their implications for land and watershed management.
Aims: This study investigated the spatiotemporal trends in air temperature and rainfall erosivity and examined their relationship in Wukari and Donga Local Government Areas of southern Taraba State, Nigeria, during 2000–2024.
Place and Duration of Study: The study was conducted in Wukari and Donga Local Government Areas of southern Taraba State using climatic data for 2000–2024.
Methodology: Monthly air temperature data were obtained from the National Aeronautics and Space Administration Prediction of Worldwide Energy Resources (NASA POWER) database. Observed daily rainfall records from the Nigerian Meteorological Agency (NiMet) stations at Jalingo, Makurdi, and Lafia were used to estimate rainfall at Wukari and Donga using the Inverse Distance Weighting (IDW) method in ArcGIS Pro 3.2. Rainfall erosivity was estimated using the Modified Fournier Index (MFI) and the Arnoldus empirical model. Trends were assessed using the Mann–Kendall trend test and Sen's slope estimator, while heat map analysis and Pearson correlation were used to evaluate temporal variability and the temperature–erosivity relationship.
Results: Rainfall erosivity increased significantly in Wukari (S = 140, Z = 3.25, p = 0.0012; Sen's slope = 20.32 MJ mm ha⁻¹ h⁻¹ yr⁻¹) and Donga (S = 132, Z = 3.06, p = 0.0022; Sen's slope = 18.76 MJ mm ha⁻¹ h⁻¹ yr⁻¹). Annual mean temperature increased by 0.051 °C yr⁻¹ in Wukari and 0.070 °C yr⁻¹ in Donga, while annual maximum temperature increased by 0.124 °C yr⁻¹ and 0.191°C yr⁻¹, respectively. Mean annual temperatures were 26.33°C in Wukari and 25.68 °C in Donga. Heat map analysis showed the highest temperatures in March–April and lower temperatures during July–September, with warmer conditions becoming more evident during 2019–2024. A positive correlation (r = 0.373) was observed between annual temperature and rainfall erosivity.
Conclusion: Southern Taraba experienced significant warming and increasing rainfall erosivity during 2000–2024, with implications for soil erosion, agricultural productivity, watershed management, and land-use planning.
Keywords: Air temperature, rainfall erosivity, modified Fournier index, Mann–Kendall trend test, Sen's slope estimator, climate variability