The Trend and Magnitude of Land Use and Land Cover Change and their Driving Forces in Lake Tana Basin, Upper Blue Nile, Northwest Ethiopia

Abstract

Monitoring the trend and magnitude of Land Use and Land Cover (LULC) change and its driving forces in the Basin provides essential information to decision-makers regarding the conservation and management of water resources. The Lake Tana Basin, situated in Ethiopia, serves as a vital ecological and economic hub, supporting diverse ecosystems and local communities. Despite its ecological and hydrological importance, unplanned LULC change predisposes the Basin to environmental problems such as land degradation, loss of habitat and biodiversity, soil erosion, water quantity degradation, and water pollution. The study utilized Geographic Information Science (GIS), Remote Sensing (RS) analysis, and key informants' perceptions to quantify and analyze the trend of spatio-temporal LULC change in the Lake Tana Basin over 20 years (2004–2024). Population increase, conservation efforts, climate change, soil fertility, and income level were assessed as potential drivers of LULC change. A supervised classification method was used on the Google Earth Engine platform to map seven LULC classes: Water Cover, Built-up Area, Forest Cover, Agricultural Land, Bare Land, Grassland, and Wetland. Classification accuracy was validated using confusion error metrics, recording overall accuracies of 86%, 97%, 95%, 93%, and 95% for the years 2004, 2009, 2014, 2019, and 2024, respectively. Post-classification change detection revealed increases in Water Cover (2.16%), Built-up Area (83.41%), Agricultural Land (38.32%), and Bare Land (39.11%), with corresponding reductions in Forest Cover (56.60%), Grassland (72.71%), and Wetland (64.06%). The study revealed that population growth significantly influenced the increase in built-up areas, reduction in forest cover, reduction in grasslands, and loss of wetlands, while an increase in water coverage was linked to climate change, and the expansion of bare land was influenced by soil type. The findings inform evidence-based policies for sustainable land use and conservation planning in the Lake Tana Basin.