2026 Vol-6 Issue-2 | HYDROCLIMATIC DRYING ACROSS NIGERIA'S FEDERAL CAPITAL TERRITORY: A PER-PIXEL TERRACLIMATE TREND FIELD AND EXTERNAL COMPARISON, 1991–2024

This study characterises long-term hydroclimatic change across Nigeria's Federal Capital Territory (FCT) from 1991 to 2024 using the gridded TerraClimate dataset at approximately 4 km resolution. Thirteen surface-climate and water-balance variables were extracted for all grid cells within the six FCT area councils, together with two external reference locations, Suleja and Keffi, using Google Earth Engine. Per-pixel trend magnitudes were estimated with Sen's slope, and monotonic trend significance was assessed using the modified Mann-Kendall test. The results indicate territory-wide hydroclimatic drying: precipitation, soil moisture, runoff and the Palmer drought index decline, while potential evapotranspiration, climatic water deficit and temperature increase across most cells. The rate of change is spatially clustered, forming a south-west to northeast gradient. Baseline-regression analysis suggests that moisture and water-balance trend gradients are closely aligned with the FCT's baseline rainfall field, whereas precipitation decline is more spatially uniform and the warming gradient is less dependent on local baseline values. Because TerraClimate derives fine spatial detail from a climatological baseline while using coarser reanalysis-driven temporal variability, the moisture-gradient interpretation should be treated as product-conditioned rather than as independent proof of orographic control. AMAC and Gwagwalada appear to occupy different positions along a territory-wide gradient rather than representing a robust urban–peri-urban contrast. The findings support planning for FCT-wide drying while prioritising faster-drying southwestern councils for adaptation, subject to validation with station observations where network density permits, land-cover data and higher-resolution seasonal analyses.