An Analysis of Urban Land Use/Land Cover Changes in Blantyre City, Southern Malawi (1994–2018)

Landslide dynamic susceptibility mapping in urban expansion area considering spatiotemporal land use and land cover change

Landslides pose a noteworthy threat in urban settlements globally, especially in areas experiencing extreme climate and rapid engineering. However, researches focusing on the long-term uninterrupted land use and land cover change (LULCC) impacted on landslide susceptibility mapping (LSM) in rapid urban expansion areas remains limited, let alone different temporal scenarios adjacency thresholds. This work aims to refine the temporal LSM considering spatiotemporal land use and land cover (LULC) and to provide decision makers with governing factors in landslides control during urbanization in mountainous areas. Herein, annual LULC data and landslide inventory spanning from 1992 to 2022 were utilized to map dynamic landslide susceptibility in Wanzhou District of the Three Gorges Reservoir Area, China. Initially, the landslide-related factors were filtered as input features of random forest (RF) model before diagnosis via multicollinearity test and Pearson Correlation Coefficient (PCC). The advanced patch-generating land use simulation (PLUS) model was then invited to fuel temporal susceptibility prediction powered by LULCC projections. Finally, the performance of various scenarios was evaluated using Receiver Characteristic Curve (ROC) curves and Shapley Additive exPlanation (SHAP) technique, with discussions on LULCC temporal adjacency thresholds and mutual feedback mechanism between territorial exploitation and landslide occurrences. The results indicate that the precision of LSM is positively correlated with the time horizon, acted by incorporating the latest LULC and LULCC achieving an area under the curve (AUC) of 0.920. The transition of land from forest to cropland and impervious areas should be avoided to minimize the increase in landslide susceptibility. Moreover, a one-year adjacency threshold of LULCC is recommended for optimal model accuracy in future LSM. This dynamic LSM framework can serve as a reference for decision makers in future landslide susceptibility mitigation and land resources utilization in rapid urban expansion areas worldwide.

Environmental surveillance for Salmonella Typhi in rivers and wastewater from an informal sewage network in Blantyre, Malawi

Environmental surveillance for Salmonella Typhi may provide information on the community-level dynamics of typhoid fever in resource poor regions experiencing high disease burden. Many knowledge gaps concerning the feasibility of ES remain, especially in areas lacking formal sewage systems. We implemented protocols for S. Typhi ES, including site selection and catchment population estimation, sample concentration and testing using qPCR for S. Typhi specific gene targets. Between May 2021 and May 2022, we collected grab samples and Moore swabs from 43 sites in Blantyre, Malawi. Catchment characteristics, water quality, and human faecal contamination (qPCR for Bacteroides HF183) were also recorded. Their association with S. Typhi detection was investigated using a logistic mixed-effects regression analysis. Prevalence of S. Typhi in ES samples was 2.1% (1.1-4.0%) and 3.9% (1.9-7.9%) for grab and Moore swab samples, respectively. HF183 was associated S. Typhi positivity, with a unit increase in log genome copies/microlitre increasing the odds of detection of S. Typhi by 1.56 (95% CI: 1.29-1.89) and 1.33 (1.10-1.61) in Moore swabs and grab samples, respectively. The location and timing of S. Typhi detection through ES was not associated with the incidence of typhoid fever reported in associated catchment populations. During this period of relatively low typhoid fever incidence, wastewater surveillance continued to detect S. Typhi in human sewage and wastewater suggesting that ES using natural river systems can be a sensitive indicator of transmission.

The spatial heterogeneity of urban green space distribution and configuration in Lilongwe City, Malawi

Urban green spaces provide several benefits related to the quality of urban life. The existence and spatial arrangement of these spaces within neighbourhoods and functional land uses have significant implications for the well-being of urban dwellers. Previous studies on green spaces in urban areas of Malawi have focused on a broader and macro-level perspective, offering insightful information on general trends in different cities. However, there is a significant research shortage in localised understanding, which requires carrying out micro-level assessments concentrating on land use zones and neighbourhoods within these cities. In this study, we used remote sensing data and landscape metrics to understand the distribution and configuration of urban green spaces in the city's neighbourhoods and functional land uses and their relationship with urban form. The study revealed that 20% of neighbourhoods fail to meet the WHO-recommended standard of 9 m2 of green space per person, with a predominant concentration of these undersupplied areas in high-density and quasi-residential zones. In addition, 56.2% of Lilongwe City's total green area was contained under functional land uses. Particularly, high-rise residential, medium-density residential, low-density residential, quasi-residential, high-rise flat area, commercial class, high-rise commercial, heavy industry, light industry, and government land use zones contained 17.3%, 12.0%, 22.2%, 12.0%, 4.1%, 6.4%, 6.1%, 5.0%, 1.6%, and 13.3% of the total green spaces in functional land uses, respectively. Importantly, this research found significant correlations between urban form metrics, namely building coverage, building density, building perimeter area ratio, road density, and the distribution and configuration of urban green spaces. This necessitates an integrated approach to urban planning and design, emphasising the importance of balancing development with green space preservation.

Assessing changes in the ecosystem service value in response to land use and land cover dynamics in Malawi

Land use and land cover (LULC) changes are inevitable outcomes of socioeconomic changes and greatly affect ecosystem services. Our study addresses the critical gap in the existing literature by providing the first comprehensive national analysis of LULC changes and their impacts on ecosystem service values (ESVs) in Malawi. We assessed changes in ecosystem service values (ESVs) in response to LULC changes using the benefit transfer method in ArcGIS 10.6 software. Our findings revealed a significant increase in grasslands, croplands, and urban areas and a notable decline in forests, shrubs, wetlands, and water bodies. Grassland, cropland, and built-up areas expanded by 52%, 1%, and 23.2%, respectively. In contrast, permanent wetlands, barren land, and water bodies declined by 27.6%, 34.3%, and 1%, respectively. The ESV declined from US$90.87 billion in 2001 to US$85.60 billion in 2022, marking a 5.8% reduction. Provisioning services increased by 0.5% while regulating, supporting, and cultural ecosystem service functions declined by 12.2%, 3.16%, and 3.22%, respectively. The increase in provisioning services was due to the expansion of cropland. However, the loss of regulating, supporting, and cultural services was mainly due to the loss of natural ecosystems. Thus, environmental policy should prioritise the conservation and restoration of natural ecosystems to enhance the ESV of Malawi.

Monitoring and simulating landscape changes: how do long-term changes in land use and long-term average climate affect regional biophysical conditions in southern Malawi?

We set out to reveal the effects of long-term changes in land use and long-term average climate on the regional biophysical environment in southern Malawi. Object-oriented supervised image classification was performed on Landsat 5 and 8 satellite images from 1990 to 2020 to identify and quantify past and present land use-land cover changes using a support vector machine classifier. Subsequently, using 2000 and 2010 land use-land cover in an artificial neural network, land use-land cover for 2020 driven by elevation, slope, precipitation and temperature, population density, poverty, distance to major roads, and distance to villages data was simulated. Between 1990 and 2020, area of land cover increased in built-up (209%), bare land (10%), and cropland (10%) and decreased in forest (30%), herbaceous (4%), shrubland (20%), and water area (20%). Overall, the findings reveal that southern Malawi is dominantly an agro-mosaic landscape shaped by the combined effects of urban and agricultural expansions and climate. The findings also suggest the need to enhance the machine learning algorithms to improve capacity for landscape modelling and, ultimately, prevention, preparedness, and response to environmental risks.

Urban Spatial Development Based on Multisource Data Analysis: A Case Study of Xianyang City’s Integration into Xi’an International Metropolis

The study of urban spatial development focuses on the process of urbanization, which involves the urban economy, population, the scale of urban construction land and the construction land’s structure. All this influences the economic structure, social structure and functional structure of the city. Taking Xianyang City, a core part of Xi’an international metropolis, as an example, this study, based on night light remote sensing data from 1992 to 2013, land use data from 1980 to 2015 (6 periods), AutoNavi Map (AMAP) Points of Interest (POI) data, and the patch-generated land use simulation model (PLUS), simulates the spatial–temporal pattern change characteristics of land use in Xianyang City from 2025 to 2035. The results show that: (1) During 1985–2015, urban land use showed a significant upward trend (p < 0.05); (2) From 1992 to 2013, the change in night light in the Xianyang City Administrative Region showed an upward trend. The gravitational center of Xianyang City’s built-up area moves southeast first and then northeast. After the beginning of 2010, the gravitational center of Xianyang City’s built-up area moved faster; (3) The distribution of different types of urban centers in Xianyang City is basically the same; (4) From 2005 to 2035, the overall land use in Xianyang City showed a trend of “multi polar explosive growth in construction land, slow growth in forest land, and first a decrease then an increase in wetland water body”. The urban spatial structure has changed from a single-center development model to a point–axis development model. The study of urban space development can provide some reference for the layout of urban construction in the future.

Estimation of Groundwater Recharge in Kumamoto Area, Japan in 2016 by Mapping Land Cover Using GIS Data and SPOT 6/7 Satellite Images

Agricultural fields, grasslands, and forests are very important areas for groundwater recharge. However, these types of land cover in the Kumamoto area, Japan, were damaged by the Kumamoto earthquake and heavy rains in 2016. In this region, where groundwater provides almost 100% of the domestic water supply for a population of about 1 million, quantitative evaluation of changes in groundwater recharge due to land cover changes induced by natural disasters is important for the sustainable use of groundwater in the future. The objective of this study was to create a land cover map and estimate the groundwater recharge in 2016. Geographic information system (GIS) data and SPOT 6/7 satellite images were used to classify the Kumamoto area into nine categories. The maximum likelihood classifier of supervised classification was applied in ENVI 5.6. Eventually, the map was cleaned up with a 21 × 21 kernel filter, which is larger than the common size of 3 × 3. The created land cover map showed good performance of the larger filter size and sufficient validity, with overall accuracy of 91.7% and a kappa coefficient of 0.88. The estimated total groundwater recharge amount reached 757.56 million m3. However, if areas of paddy field, grassland, and forest had not been reduced due to the natural disasters, it is estimated that the total groundwater recharge amount would have been 759.86 million m3, meaning a decrease of 2.30 million m3 in total. The decrease of 2.13 million m3 in the paddy fields is temporary, because the paddy fields and irrigation channels have been improved and the recharge amount will recover. On the other hand, since the topsoil on the landslide scars will not recover easily in natural conditions, it is expected to take at least 100 years for the groundwater recharge to return to its original state. The recharge amount was estimated to decrease by 0.17 million m3 due to landslides. This amount is quite small compared to the total recharge amount. However, since the reduced recharge amount accounts for the annual water consumption for 1362 people, and 12.1% of the recharge decrease of 1.41 million m3 each year to fiscal year 2024 is expected by municipalities, we conclude that efforts should be made to compensate for the reduced amount due to the disasters.

Spatial-Temporal Land Use and Land Cover Changes in Urban Areas Using Remote Sensing Images and GIS Analysis: The Case Study of Opole, Poland

Urban expansion is a dynamic and complex phenomenon, often involving adverse changes in land use and land cover (LULC). This paper uses satellite imagery from Landsat-5 TM, Landsat-8 OLI, Sentinel-2 MSI, and GIS technology to analyse LULC changes in 2000, 2005, 2010, 2015, and 2020. The research was carried out in Opole, the capital of the Opole Agglomeration (south-western Poland). Maps produced from supervised spectral classification of remote sensing data revealed that in 20 years, built-up areas have increased about 40%, mainly at the expense of agricultural land. Detection of changes in the spatial pattern of LULC showed that the highest average rate of increase in built-up areas occurred in the zone 3–6 km (11.7%) and above 6 km (10.4%) from the centre of Opole. The analysis of the increase of built-up land in relation to the decreasing population (SDG 11.3.1) has confirmed the ongoing process of demographic suburbanisation. The paper shows that satellite imagery and GIS can be a valuable tool for local authorities and planners to monitor the scale of urbanisation processes for the purpose of adapting space management procedures to the changing environment.

Impact of land use/land cover dynamics on ecosystem service value-a case from Lake Malombe, Southern Malawi

Lake Malombe ecosystem provides a vast range of services that are vital for the sustenance of the riparian communities. Understanding land use and land cover (LULC) dynamics, as well as the associated impacts on the multiple ecosystem service value (ESV), is extremely important in decision-making processes and effective implementation of an ecosystem-based management approach. This study analyzed the LULC dynamics from 1989 to 2019. The primary objective of the study was to assess its impact on ecosystem services (ES). The ESV was determined using LULC analysis and established global ESV coefficient. The LULC analysis showed a reduction in forest cover by 84.73% during the study period. Built-up, cultivated land, bare land, shrubs, and grassland increased considerably. Rapid population growth, climate change, government policy conflicts, and poverty were identified as the most important drivers of LULC dynamics. Based on ESVs estimations, the ES changes instigated by LULC dynamics in the study area result in an average loss of US$45.58 million during the study period. Within the same period, the lake fishery also recorded a net loss of US$8.63 million. The highest net loss of US$79.832 million was recorded from 1999 to 2019 due to increased loss of forest, a decrease in water bodies and marsh areas. The sensitivity analysis (CS) indicated that our estimates were relatively robust. This study findings provide a piece of empirical evidence that LULC dynamics in the Lake Malombe catchment have led to a significant loss of ESVs, with serious implications for the livelihoods of the local population.

Spatiotemporal Analysis of Urbanization Using GIS and Remote Sensing in Developing Countries

The international statistics show that the global urban population will increase by up to 68% by 2050 [...]

A Socio-Spatial Analysis of Land Use Dynamics and Process of Land Intervention in the Peri-Urban Areas of Bahir Dar City

The contemporary urbanization and its implication to land use dynamics especially in the peri-urban areas are emerging as a cross-cutting theme in policy debates and scientific discourse. As most cities in developing countries, including Ethiopia, are experiencing continuous expansion of built-ups and dynamic land use changes, monitoring and an in-depth analysis of the past, present and future predictions of these changes are important for a holistic understanding of the problem, its consequence, and to regulate proper land use intervention options. Thus, the main objective of this research is to assess land use dynamics and processes of land intervention in the peri-urban areas of Bahir Dar city using a socio-spatial analysis. It assesses to what extent the existing peri-urban land intervention processes and land use decisions are effective in combating and controlling unwanted land use changes. Primary socio-economic data were collected using questionnaires, focus group discussions (FGDs) and key informant interviews; in addition, spatial data including Landsat and Sentinel imageries of 1993, 2001, 2011 and 2020 were utilized. Land use/land cover (LULC) classes were computed using the integration of spectral and object-based image classification techniques. The results signal that built-ups are expanding horizontally with unpredicted patterns. This is because the existing land intervention processes are lacking effectiveness to govern the spatial patterns of built-ups. The results further depict that processes of land use intervention do not only determine horizontal urban expansion but also determine the nature of people-to-land relationships, which involve both formal and informal processes. This creates haphazard, disputed and unregulated land use systems in peri-urban areas of Bahir Dar. The socio-spatial methodology applied in this research is effective in monitoring both the spatial and social dimensions of land use changes. The spatial results effectively demonstrate the dynamics of land uses; whereas, the social analysis supports understanding of the processes of land use interventions. In conclusion, monitoring processes of land use interventions are key policy and decision making directions to regulate and manage land use dynamics in the peri-urban area.