This study was carried out in Nkafu district, located in Kadutu municipality (in the city of Bukavu, South Kivu, eastern DR Congo). Bukavu has a very hilly terrain with slopes around 75%. In fact, the lowest point is at 1417 m above sea level, and the highest is at 2172 m with a difference of 755 m above sea level (Figure 1). Bukavu covers ~63 km², with the majority (43 km²) covered by upland and 20 km² by Lake Kivu water ( Bilubi, 2014 ; Chako et al., 2022 ). According to Ntamusimwa et al. (2022) , Bukavu covers 43 km² and is divided into 3 districts: Kadutu (6.68 km²), Ibanda (13.38 km²) and Bagira (23.26 km²), with Kadutu being the main commercial center and Ibanda the administrative district of South Kivu province.

Bukavu has a humid tropical climate, with temperature variations influenced by its elevation and sub-equatorial position. Vegetation in Bukavu is dominated by tree species (e.g. eucalyptus, cypress, etc.), agroforestry and fruit tree species (e.g. mango, guava, lemon, orange, avocado, etc.) and a number of wild grass species (e.g. Tithonia diversifolia, Lantana camara, Galinsango parviflora, and Commelina diffusa, etc.).

Bukavu’s soil is generally basaltic. It’s not completely clayey, as it’s much more compact. However, it is also less permeable and highly susceptible to drought. Bukavu’s hilly terrain and climate combine to create one of the most sensitive cities to environmental hazards such as soil erosion ( Eisenberg & Muvundja, 2020 ; Chako et al., 2022 ), and landslides ( Bigirimwami, 2009 ; Maki Mateso & Dewitte, 2014 ; Balegamire et al., 2017 ; Kulimushi et al., 2017 ; Mugaruka et al., 2017 ;

Ntamusimwa et al., 2022 ) which are increasingly occurring in this town faced with rapid population growth.

Figure 2 shows the spatio-temporal change in land use in the Bukavu town from 2000 to 2021. In fact, urbanization is changing over time in many parts of the town, which is characterized by hilly terrain. The land use change from 2000 to 2021 is presented in the Table 1.

Data collection based on a household survey using a questionnaire combined with an interview with the local authorities of Kadutu municipality. Household

characteristics (socio-demographic and economic) were collected from members aged over 18. In addition, information on land tenure security and conformity with urban planning regulations were collected from household heads in the Nkafu district. To achieve this, 283 respondents were selected. Survey data were input using Microsoft Excel, and descriptive analyses were performed using the Statistical Software XLStat version 2019 package.

Household characteristics in the study area are presented in Table 2.

Results in Table 1 show that most household heads in the study area were men (96.2%) aged over 60, while those aged from 30 to 40 represented the lowest category. Most respondents were married (91.5%), while others were single (2.7%) or in other marital status (5.8%). The majority had no formal education (54.6%), while those with secondary, post-secondary and primary education represented 3.8%, 3.8%, 8.5%, and 29.4% respectively. Most (65.5%) respondents had lived in the study area between 6 and 10 years, and had trade as their main household income source.

Results of Land and building administration in the study area are presented in Table 3.

Results in Table 2 shows that most respondents (73.7%) were landowners who lived in simple houses (60.8%) built with unsustainable bulding materials or wood (55.6%) with 3 to 5 rooms (72.4%). Most landowners in the study area obtained their plots by buying them (53.2%), but were separated from the road by more than 5 plots (63.8%).

Results of Land policy and urban environment management are presented in Table 4.

Results in Table 2 shows that most (65%) respondents did not appreciate the current land administration by the authorities and/or neighbors, and in the case of land conflicts, more than half (86.3%) reached negotiated agreement. In fact, the majority (72%) of respondents had indicated that access to housing plots was one of the reasons for a good urban planning policy, while 32% of respondents had indicated that access to housing plots and uncontrolled construction (29.4%) were the main reasons for a poor land administration policy for building. Soil erosion (4.8%), insalubrity (5.8%), landslides (8.5%), fire frequency (9.6%) and land conflicts (9.9%) were considered to be consequences of the poor urbanization policy. To adapt to the conditions of urbanization, 48.5% and 30.4% of respondents respectively suggested the delineation of plot boundaries and respect for building standards to be the main corrective strategies.

Results of urban environment and householder waste management are presented in Table 5.

Results in Table 2 shows that most respondents (59.4%) indicated that there is a good waste management policy in the area, to protect the urban environment. More than half of respondents (53.9%) use household waste collection systems, while only 1% incinerates their waste. In fact, the majority (79.5%) indicated that environmental regulations are not respected in the study area, and for 48.5% of households, this is mainly due to a lack of financial resources. Road rehabilitation (50.2%) and public waste management (30.7%) are the main recommendations for good urban environmental governance.

The results show that respondents do not appreciate the land policy of the area where they are located, and this is due to the many consequences that local people experience on a day-to-day level. According to Town et al. (2018) , Rapid, uncontrolled urbanization has major impacts on the urban environment, particularly in the case of uncontrolled construction, which is one of the main characteristics of shanty towns around major cities. Uncontrolled urban growth is also characterized by environmental pollution and poor access to basic services and infrastructures. In addition, findings of Doygun (2020) show that local perceptions of urbanization are based on poor land management associated with poor environmental management caused by poor sanitation services, which have an impact on public health in low-income areas such as our study area.

Ntamusimwa et al. (2022) indicated that rapid, uncontrolled urbanization in Bukavu’s districts is one of the consequences of the city’s limited expansion, which is also having a negative impact on restructuring by increasing its susceptibility to natural and anthropogenic hazards such as landslides ( Bigirimwami, 2009 ; Bunduki et al., 2015 ; UEA-PNUD, 2018 ), soil erosion ( UEA-PNUD, 2018 ; Chako et al., 2022 ), flooding ( Mawemba, 2016 ; UEA-PNUD, 2018 ), wildfire ( Banza et al., 2022 ). Natural and anthropogenic hazards occurring at the same time in the study area are directly linked to the poor land policy in the study area, where the hilly terrain has a negative impact on land planning. Results of Yi et al. (2016) show that urbanization in highland regions requires hillside protection measures, which in the context of poor land-use planning can lead to landslides and material and human damage.

Urban waste management is one of respondents’ recommendations for good urban environmental management. Results of Kassoum (2013) show, for example, that uncontrolled construction in developing countries is at the origin of inadequate urban waste management. However, local community knowledge of waste management is one of the main strategies for participative management of the urban environment. According to Benti et al. (2022) , all these consequences are mainly due to poor land resource governance for successful and effective land planning. Rapid urbanization and land policy in general have been the driving factors of major environmental and social changes in land policies worldwide ( Richards et al., 2020 ). However, a number of previous studies indicate that integrated land-use planning with Geographic Information Systems (GIS) is one of the major tools of effective land-use policy, with highly promising results in reducing the social and environmental consequences of land-use planning in many parts of the world ( Farhan & Al-shawamreh, 2019 ).

Poor sewage systems are one of the main consequences of the inappropriate land-use policy in the study area, which is characterized by the rapid growth of built-up areas. Results of Mulalisi (2016) in the Panzi district of Bukavu (DR Congo) show that rapid, uncontrolled urbanization is one of the main causes of the poor urban and environmental policies affecting land use and waste management. In Nkafu, for example, rapid, and uncontrolled urbanization is also associated with socio-economic factors, characterized by small businesses that are the livelihoods of most of the area’s population.

Local perception and knowledge of urbanization vary from one respondent to another, but the impact of peri-urbanization and rapid urbanization is poorly known in most municipalities where land-use planning policies are not respected ( Hatab et al., 2022 ). Natural hazards, land conflicts, land access difficulty, etc. are the main consequences perceived by the people in the study area. Results of Jurkovič (2014) agree with our findings, revealing that the public planning of land areas causes serious problems for environmental management, by limiting comfort in the residential areas of rapid urbanized cities. According to Peltonen & Sairinen (2010) and Magsi et al. (2017) , increasing conflict in developing countries is caused by the lack of social justice and can be seen as a result of factors associated with the availability of resources (e.g. farmland, houses and other physical resources), especially in peri-urban areas.

Our results show that local communities are not involved in land planning as part of the effective management of the urban environment. This can be attributed to the government’s policy of public land administration. On the other hand, the results of ( van Empel, 2008 ) demonstrate that the effective participation of local communities in land administration is one of the most effective strategies contributing significantly to participatory land planning and development. Furthermore, the results of Butta (2020) show that social inequalities have an impact on the urbanization rate (popular and physical) in most poor-country cities, where the land administration sector’s resources are insufficient to develop the land tenure system.