Proposal of UAV-Lidar and photogrammetry-based modeling for assessing soil loss using nature-based solutions as countermeasure in urban areas in DRC

Mass movements due to soil erosion, intense rains and water runoff in sandy soils represent a major socio-ecological problem in the Democratic Republic of Congo (DRC). Kinshasa, Kananga and other urban areas in DRC are currently challenged by severe forms of land degradation.

Natural resources are being exploited at high rates due to unplanned human settling pressed by migration and population growth. Consequently, demanding energy, forestry, agricultural goods and services that undermine tropical forests, savannas and monsoon forests, which are fragile and high value ecosystems.

The effects of forest lost are exacerbated by growing urban areas with drainage mismanagement in anarchic urban environments due to concentrated and disorganized flow. Rain events between 2019 and 2022 have compromised or destroyed basic structure such as railroads and main streets, considered key lifelines that have already caused human, environmental and infrastructural losses.

Reliable rain data records are scarce or inexistent; however, intense, heavy, punctual rain events can be identified throughout the dry and rainy season. No particular erosive effect can be attributed to these events without consistent Intensity-duration-frequency (IDF) data. On the other hand, slope instability has been well documented through satellite imagery and demonstrated exponential growth since 2010. Aero transported Lidar, photogrammetry and cloud point technique have been used to map urban growth, vegetation cover and soil management practices in four study sites, in between seasons.

Hence, this study proposes to systemize a methodology that assesses soil degradation and stability risks; evaluating the effectiveness of NBS to reduce soil erodibility through the combination of agroecological solutions, engineering risk management in urban and peri-urban environments facing climate change challenges. This is a project currently under research and execution by the Government of DRC with the support of the World Bank.