Spatial distribution of rainfall in Nigeria

Abstract

This study investigates the spatial distribution of rainfall in Nigeria, utilizing ground-based rainfall data from 48 weather stations and two long-term satellite-based precipitation products spanning 39 years (1981–2019). Employing statistical techniques and kriging interpolation methods, this study analysed annual and seasonal rainfall patterns. Correlation coefficient was also used to compare areal averages of satellite-based rainfall estimates and ground-based rainfall data in Nigeria and for each of the six eco-climatic regions. Results indicate significant regional disparities, with the Tropical Wet (Mangrove and Swamp) region receiving the highest mean annual rainfall (> 2,300 mm) and the Sahel Savannah experiencing the lowest (< 450 mm). Eco-climatic regions exhibit varying contributions to total annual precipitation, with mangrove swamps and tropical rainforests dominating. Notably, 76.4% of annual rainfall occurs during the June–August and September–November periods, with August witnessing peak precipitation levels. Over Nigeria, there are strong correlations between satellite precipitation estimates (SPEs) and ground data on a monthly and seasonal basis, but the correlations are weaker on an annual scale, especially in Sahel and Montane regions. While SPEs provide reliable short-term rainfall estimates, caution is advised for annual precipitation estimates, particularly in regions with lower correlations. This study highlights the need for more efficient water use methods, with an emphasis on enhanced storage systems, distribution networks, sustainable irrigation practices, and judicious consumption to address rainfall variability. The findings highlight the importance of understanding rainfall distribution for agricultural planning and regional climate assessments. By integrating ground-based and satellite-derived data, this study enhances knowledge of Nigeria's climate dynamics, facilitating informed decision-making and resource management strategies.