GEOSPATIAL MAPPING OF URBAN DRAINAGE INFRASTRUCTURE AND SEASONAL LAND SURFACE TEMPERATURE (LST) DYNAMICS IN LAPAI, NIGER STATE, NIGERIA (2021–2025)

Abstract

Rapid urbanization in sub-Saharan secondary cities outpaces infrastructure, driving drainage failures and thermal stress. This study evaluated the spatiotemporal interaction between stormwater drainage architecture and multi-temporal Land Surface Temperature (LST) regimes across dry and wet seasons (2021–2025) in Lapai, Niger State using VHR Google Earth imagery, Landsat 8/9, Sentinel-2, and SRTM DEMs, the drainage network and thermal dynamics were mapped over a 12– 15 km² area, the 28.5 km mapped open concrete network shows that only 42% is fully functional, while 58% is impaired by siltation/partial blockages (38%) or complete collapse and refuse accumulation (20%). High-density commercial and residential centers (Lapai Central Market, Motor Park, Badegi, and Ungwan Hausawa) exhibit functional drainage densities below 0.5 km/km2 . Concrete infrastructure, priority corridor placement, and continuous outlets dictate functionality. Dry-season thermal retrievals revealed extreme LST values (42∘C–72∘C) which is concentrated over poorly drained central and northern interfluves. Wet-season LST is suppressed landscape-wide and remains volatile due to precipitation dynamic which demonstrating a rigid internal thermal contrast. Critical hubs (Lapai Central Market, Motor Park, Madaki, Ungwan Sarki) face severe deficits (???????????? < 0.5 km/km2 ) which conflicts with planned zones reaching 1.8 km/km2. Overall, drainage deficits intensify microclimatic heat retention, establishing empirical baselines for climate-resilient planning.