Multi-sensorial data-based assessment of artificial surfaces and vegetation index for the response to population expansion: A case study of Musanze Secondary City, Rwanda

Abstract

Rapid population growth impacts land use, especially in Musanze, a secondary city.  Therefore, our research aims for spatial analyses of the time series change in artificial surfaces and NDVI from 2000 to 2020. A multi-sensorial data-based analysis method assessed the changes and their effects on sustainability. Mathematical expression results reveal that (1) cultivated land increased from 64.6% to 68.9%, signifying a 4.3% rise. Conversely, forested areas decreased from 30.9% to 25.4%, reflecting a notable reduction of -5.5%. Water bodies saw a marginal uptick from 3.4% to 3.5%, a modest increase of 0.1%. Notably, artificial surfaces nearly doubled, soaring from 1.1% to 2.2%, representing an approximate 1.1% expansion in total coverage. (2) In 2000, sampled points demonstrated elevated vegetation indices, signifying that artificial areas were notably smaller than natural ones. Fast forward to 2020, after artificial surfaces had completely covered the sampled area, a significant and notable decrease in the vegetation index was observed, effectively halving the initial value recorded in 2000. In summary, urbanization can foster well-coordinated development; however, it poses a significant threat to natural areas as people migrate to urban centers. Therefore, to ensure a sustainable future for the population, we recommend enforcing zoning plans and building upward, using taller residential buildings instead of spreading out horizontally.