Evaluating land cover change and its impact on hydrological regime in Upper Shire River Catchment, Malawi

A study was conducted to investigate hydrological impacts of land cover changes in the degradation of the hydrological on flow regimes of the Upper Shire river, Malawi. Remote sensing techniques were used to inventory temporal changes of land cover changes in the catchment. Hydrological data were analyzed to reveal the alterations ecosystems, and water resources for an informed decision on proper catchment planning and management and trends for two periods; 1989 and 2002. The study revealed significant changes in magnitude and direction that have occurred in the catchment between 1989 and 2002, mainly in areas of human habitation. Trends in land cover change in the Upper Shire river catchment depict land cover transition from woodlands to mostly cultivated/ grazing and built-up areas. The land cover mapping showed that 23% of the land was covered by agricultural land in 1989. Subsistence agricultural area has increased by 18%, occupying 41% of the study area in 2002. The effects of the derived land cover changes on river flow in the Upper Shire river were investigated using the semi distributed soil and water assessment tool (SWAT) model. River flows were found to be highly variable and sensitive to land cover changes. Simulation results show that 2002 land cover data produces higher flow peaks and faster travel times compared to the 1989 land cover data. The changes detected indicate the effects of land use pressure in the catchment. The study highlights the importance of considering effects of land use and land cover changes on ecosystems, and water resources for an informed decision on proper catchment planning and management

Evaluating derived vegetation indices and cover fraction to estimate rangeland aboveground biomass in semi-arid environments

This study was conducted to assess satellite data for quantifying and mapping the spatial distribution of rangeland biophysical parameters (aboveground biomass) from different geographic locations in the North West province, South Africa. Two major factors affecting the quality and conditions of the rangelands, namely rainfall zones and grazing intensities, were used to define sampling classes to represent the predominantly Savanah environment. Remote sensing vegetation indices (NDVI and SAVI) and vegetation cover fraction (SMA) were used to quantify the aboveground biomass using regression models of the sample aboveground biomass as a function. Results showed that private ranches in high rainfall areas yielded the highest above ground biomass (159 kg 100 m-2) while the lowest biomass yield (10 kg 100 m-2) was obtained from the communal rangelands in the low rainfall area. The SAVI performed well (0.64) in the low rainfall areas but the coefficient of determination between the AGB and SAVI was not significant (at p ≤ 0.05). The SMA also performed better than the NDVI (0.53) in the low rainfall areas but because of its weaknesses (0.57 and 0.48) in the high and medium rainfall areas, respectively, this tool is not ideal for quantifying AGB in the North West Province. In spite of its weakness in the low rainfall areas (0.47), the NDVI had displayed stronger coefficient of determination (0.63 and 0.70) with the AGB in the medium and high rainfall zones respectively. From a management perspective, remote sensing techniques appears to be a good alternative for managing and monitoring spatial and temporal AGB production, which is a major determinant for rangeland quality assessmen

Modelling a critical infrastructure-driven spatial database for proactive disaster management: A developing country context

The understanding and institutionalisation of the seamless link between urban critical infrastructure and disaster management has greatly helped the developed world to establish effective disaster management processes. However, this link is conspicuously missing in developing countries, where disaster management has been more reactive than proactive. The consequence of this is typified in poor response time and uncoordinated ways in which disasters and emergency situations are handled. As is the case with many Nigerian cities, the challenges of urban development in the city of Abeokuta have limited the effectiveness of disaster and emergency first responders and managers. Using geospatial techniques, the study attempted to design and deploy a spatial database running a web-based information system to track the characteristics and distribution of critical infrastructure for effective use during disaster and emergencies, with the purpose of proactively improving disaster and emergency management processes in Abeokuta. Keywords: Disaster Management; Emergency; Critical Infrastructure; Geospatial Database; Developing Countries; Nigeri

Toxic Heavy Metals in Soil and Plants from a Gold Mining Area, South Africa

The mining of mineral deposits abundant in South Africa has led to the release of toxic heavy metals into the environment. The aim of this study was to investigate heavy metal pollution from a gold mining area. The concentrations of arsenic, cadmium, lead, and zinc were analyzed in soil and plants found within 500 m and 1000 m radius of a gold mine established in North-West. The concentrations of these heavy metals were determined using Inductively Coupled Plasma Mass Spectrometry. The results showed that the concentrations of the studied heavy metals were all below the national and international threshold but higher than the concentrations found several kilometers away from the mining area, the natural background concentration. The results from the pollution load index shows that the topsoil is contaminated for the selected heavy metals. There was accumulation of the studied heavy metals in the studied Eragrostis hypnoides plant’s leaves and roots. In this study, it was revealed that zinc and cadmium bioaccumulated in the plant via the soil. These findings suggests that the consumption of agricultural products from farms within the 1 km radius of the mining site could be detrimental to the wellbeing of direct and indirect consumers

Land cover change and hydrological regimes in the Shire River Catchment, Malawi

D.Phil.Land cover changes associated with growing human populations and expected changes in climatic conditions are likely to accelerate alterations in hydrological phenomena and processes on various scales. Subsequently, these changes could significantly influence the quantity and quality of water resources for both nature and human society. Documenting the distribution of land cover types within the Shire River catchment is the foundation for applications in this study of the hydrology of the Shire catchment. The aim of this study is to investigate the relationships between the measured land cover changes and hydrological regimes in the Shire River Catchment in Malawi. Maps depicting land cover dynamics for 1989 and 2002 were derived from multispectral and multi-temporal Landsat 5 (1989) and Landsat 7 ETM+ (2002) satellite remote sensing data for this catchment. Other spectral-independent data sets included the 90-m resolution Shuttle Radar Topographic Mission (SRTM) digital elevation model (DEM), Geographical Information System (GIS) layers of soils, geology and archived land cover. Core image-derived data sets such as individual Landsat bands, Normalized Difference Vegetation Index (NDVI), Principal Components Analysis and Tasseled Cap transformations were computed. From generated composite images, land cover classes were identified using a maximum likelihood algorithm. Eight land cover classes were mapped. A hierarchical multispectral shape classifier with an object conditional approach determined by the Food and Agriculture Organisation (FAO) Land Cover Classification System (LCCS) legend structure was used to map land cover variables. LCCS was used as a basis for classification to achieve legend harmonization within Africa and on a global scale. Flexibility of the hierarchical system allowed incorporation of digital elevation objects, soil and underlying geological features as well as other available geographical data sets. This approach improved classification accuracy and can be adopted to discriminate land cover features at several scales, which are internally relatively homogeneous.In addition to compatibility with the FAO/LCCS classification system, the derived land cover maps have provided recent and improved classification accuracy, and added thematic detail compared to the existing 1992 land cover maps. Fieldwork was conducted to validate the land cover classes identified during classification. Accuracy assessment was based on the correlation between ground reference samples collected during field exercise and the satellite image classification. The overall mapping accuracy was 87%, with individual classes being mapped at accuracies of above 77% for both user and producer accuracy. The combination of Landsat images, vector data and detailed ground truthing information was used successfully to classify land cover of the Shire River catchment for years 1989 and 2002

Physico-Chemical and Microbial Analysis of Selected Borehole Water in Mahikeng, South Africa

Groundwater is generally considered a “safe source” of drinking water because it is abstracted with low microbial load with little need for treatment before drinking. However, groundwater resources are commonly vulnerable to pollution, which may degrade their quality. An assessment of microbial and physicochemical qualities of borehole water in the rural environs of Mahikeng town, South Africa, was carried out. The study aimed at determining levels of physicochemical (temperature, pH, turbidity and nitrate) and bacteriological (both faecal and total coliform bacteria) contaminants in drinking water using standard microbiology methods. Furthermore, identities of isolates were determined using the API 20E assay. Results were compared with World Health Organisation (WHO) and Department of Water Affairs (DWAF-SA) water quality drinking standards. All analyses for physicochemical parameters were within acceptable limits except for turbidity while microbial loads during spring were higher than the WHO and DWAF thresholds. The detection of Escherichia coli, Salmonella and Klebsiella species in borehole water that was intended for human consumption suggests that water from these sources may pose severe health risks to consumers and is unsuitable for direct human consumption without treatment. The study recommends mobilisation of onsite treatment interventions to protect the households from further possible consequences of using the water

Land cover mapping in the Upper Shire River catchment in Malawi using Landsat satellite data

Land cover mapping forms a reference base for resource managers in their decision-making processes to guide rural/urban growth and management of natural resources. The aim of this study was to map land cover dynamics within the Upper Shire River catchment, Malawi. The article promotes innovation of automated land cover mapping based on remote sensing information to generate data products that are both appropriate to, and usable within different scientific applications in developing countries such as Malawi. To determine land cover dynamics, 1989 and 2002 Landsat images were used. Image bands were combined in transformations and indices with physical meaning; together with spatial data, to enhance classification accuracy. A maximum likelihood classification for each image was computed for identification of land cover variables. The results showed that the combination of spatial and digital data enhanced classification accuracy and the ability to categorise land cover features, which are relatively inhomogeneou

Land Use Change Assessment and Water Quality of Ephemeral Ponds for Irrigation in the North West Province, South Africa

In the semi-arid environments of the North West province of South Africa the amount, timing, and distribution of rainfall is irregular, while water accessibility is a key factor in production. In line with this, a study was conducted to assess the impact of land use change on water quality and water depth within the sub-catchment areas of ephemeral ponds. To determine land use dynamics, 2004 and 2013 Landsat images were classified using maximum likelihood algorithm. Pond water quality was analysed for physical, chemical, and microbiological parameters using standard the American Public Health Association (APHA) methods. Multiple linear regression models were computed to determine relationships between land use changes and water quality parameters. Results revealed a reduction in grass cover, whereas built-up areas increased at the expense of bare land. All the values for the physical characteristics were higher than the recommended Department of Water Affairs (DWAF) and Food and Agriculture Organisation (FAO) limits, but chemical parameters, except cadmium, were within limits. Regression showed that bare areas have a positive effect on Escherichia coli (E. coli) in ephemeral pond water. The study highlights the suitability of pond water for irrigation to increase crop production and the effects of land use changes on ecosystems as critical for proper catchment planning, water resource management, and food security

Anthropogenic Land Use and Land Cover Change as Potential Drivers of Sediment Sources in the Upper Crocodile River, North West Province, South Africa

In this study, we investigated the accelerating pace of anthropogenic land use and land cover change (LULCC) disturbance, which has generated enormous impacts on the Crocodile River. Spot images from 1996, 2009 and 2022 were used to generate the land use maps and quantify the changes. A supervised classification with the maximum likelihood classifier was used to classify the images. Sediment sources were classified into two sources, revealed by erosional characteristics in the catchment. A gamma spectrometry detector, high-purity germanium (HPGe) “Well” detector by Canberra and inductively coupled plasma mass spectrometry (ICP–MS) were used for the analysis of the samples. The results revealed that from 1996–2022, built-up areas, bare land and water bodies increased by 3.48%, 2.47% and 1.90%, respectively. All the LULCC classes increased annually from 1996–2022, except for grassland, which shrunk. The results of the radionuclides analysis showed that 210Pbex was found to be a more effective tracer than 137Cs. The mass balance model revealed that subsurface sources contributed 60%, while surface sources contributed 40%, of the sediment load in the river. This research provides valuable information necessary for integrated catchment management policies for future LULCC and soil erosion to be adopted