Urbanization, landscape dynamics, and ecological vulnerability in Kisangani and its surrounding areas (Tshopo, DR Congo): spatial and prospective approaches

Over the past decades, demographic growth, economic transformations, and
technological advances have profoundly reshaped global territorial dynamics. This
evolution has led to accelerated urbanization, particularly pronounced in sub-Saharan
Africa, where urban expansion often occurs outside established planning frameworks.
This transition is characterized by diffuse spatial growth and increased landscape
fragmentation. Intermediate cities, such as Kisangani in the Democratic Republic of
Congo, offer a valuable setting for investigating the links between urban growth,
environmental degradation, and territorial sustainability. This thesis addresses this
issue by analyzing the spatial, ecological, and microclimatic transformations induced
by urban expansion in Kisangani and evaluating planning scenarios to enhance its
sustainability. To this end, an integrated approach combining remote sensing,
landscape ecology, and prospective modeling was employed.
Analyses highlighted rapid, continuous urban and peri-urban expansion between
1987 and 2021, with the urban core increasing from 13.49 km² to 100.49 km²,
corresponding to an average annual growth rate of 8.2%. This growth results from a
dual process of diffusion and coalescence and is accompanied by persistent
densification. Notably, Kisangani diverges from the global tendency toward urban
dedensification, despite the marked peri-urbanization observed between 2010 and
2021. Concurrently, the city lost nearly 47% of its mature forests, which were either
converted to agricultural land or degraded, reflecting increasing pressure from human
activities. Urban pressure also caused marked fragmentation of peripheral forest
landscapes (Masako, Mbiye, Yoko, and Yangambi), particularly severe in Masako
and Mbiye, where contiguous forest patches have almost disappeared. Since 2016,
these landscapes have lost their core areas, with the interior/edge ratio approaching
zero across all ecological distances used (50-200 m). The breakdown of ecological
connectivity, especially in Masako and Mbiye, is reflected in the weak correlation
between forest patch size and land surface temperature (LST), indicating advanced
degradation of the remaining forest fragments. At the urban microclimatic level,
landscape artificialization has intensified urban heat islands (UHIs) between 2000 and
2024: moderate UHIs more than doubled from 16 to 38 km², while high UHIs
increased from 9 to 19 km². Finally, prospective modeling highlights differentiated
trajectories: the business-as-usual scenario extends current dispersion; the sustainable
scenario illustrates the potential for compact, ecological urbanization; and the hybrid
sustainable scenario offers a realistic compromise between growth and environmental
preservation. These results reveal the interdependence among urban dynamics,
ecological degradation, and microclimatic alteration, underscoring the importance of
integrated planning that effectively coordinates institutional, scientific, and
community stakeholders