Assessing the impact of land use and land cover (LULC) changes on the surface runoff downstream of an ungauged Bontanga watershed in Northern Ghana

Abstract

Anthropogenic activities exacerbated by population growth, demanding land for food production and settlements, have led degradation of the Bontanga watershed. The aim of this study was to assess the impact of land use and land cover (LULC) change on the surface runoff in the Bontanga watershed from 1997 to 2022. LULC change maps for the years 1997, 2002, 2013, and 2022 were generated from Landsat images using ArcGIS, achieving overall accuracies of 92, 91.89, 95.27, and 83.64%, respectively. Surface runoff was estimated using the SCS–CN model. Correlation analysis was employed to identify predominant LULC change classes that impact surface runoff. The agricultural land and built-up area increased by 20.81% and 27.20% causing an increase in the surface runoff by 13.92 and 14.49% from 1997 to 2022. Due to anthropogenic activities, dense forest, grassland, mixed forest and shrub land, mixed shrub and grassland decreased by 20.31, 29.97, 22.51, and 25.58% causing an increase in surface runoff by 14.98, 14.06, 15.78, and 15.05%, respectively. Correlation analysis showed that changes in surface runoff were positively correlated with agricultural land, and mixed forest and shrub and negatively correlated with mixed shrub and grassland, and grassland.