Mapping and Monitoring Desertification Dynamics in the Sudan Savanna Zone of Kano State

Desertification in Kano State's Sudan Savanna zone represents an escalating land degradation crisis in Nigeria's North West geopolitical zone, driven by population pressure on fragile dryland soils, reduced fallow periods, firewood harvesting, and increasingly erratic rainfall that collectively undermine the ecological carrying capacity of farming and grazing systems across the state's northern districts. This study maps and monitors desertification dynamics in Kano State's Sudan Savanna zone using a multi-indicator remote sensing approach validated by field survey, covering the period 2010 to 2023. Desertification indicators derived from Landsat 8 and Sentinel-2 imagery included NDVI trends, Soil Adjusted Vegetation Index, albedo changes, and wind erosion risk index. Rain-use efficiency was computed as the ratio of annual NDVI integral to annual rainfall total from CHIRPS precipitation data, serving as a climate-independent productivity indicator. Field surveys at 55 stratified sampling stations conducted in 2023 measured soil organic carbon, bare soil fraction, grass cover, shrub density, and sand dune morphology as ground-truth desertification indicators. Trend analysis using Mann-Kendall tests was applied to each indicator time series to identify statistically significant directional change. Results identify 24 percent of Kano State's Sudan Savanna zone as showing statistically significant declining rain-use efficiency over the study period, indicating biophysical degradation independent of rainfall variation. Sand dune activation is recorded at 14 locations, with dune migration rates of 2.1 to 6.4 metres per year. The study presents the first multi-indicator desertification monitoring atlas for Kano State and recommends this as a replicable template for other savanna states. Keywords: desertification, Sudan Savanna, Kano State, North West Nigeria, remote sensing.