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- ItemAssessment of river-groundwater interactions in the Barotse floodplain, Western Zambia.(The University of Zambia, 2022) Mataa, MulemaFloodplains are among the most dynamic, productive, diverse, and threatened ecosystems in the world. Their interactions between ground and surface water is a key element in understanding the resilience of floodplains to hydrological changes, especially with the advent of climate change and variability that has affected many aquatic ecosystems. Conjunctive evaluation of ground and surface water in floodplains is critical for integrated water resources management. The main objective of this study was to evaluate groundwater-surface water interactions in the Barotse Floodplain. To achieve this objective, remote sensing was employed to identify perennial green vegetated areas with a shallow depth to groundwater table in the floodplain. Normalised Difference Vegetation Index (NDVI) and Soil Adjusted Vegetation Index (SAVI) using Sentinel-2 imagery from 2015 to 2020 using a cloud computing approach in Google Earth Engine (GEE), were used to identify riverine perrennially green vegetation. Digital filtering using “EcoHydRology Library” in R statistical package was used to determine the Base Flow Index (BFI) from the hydrograph discharge data collected from the three main gauging stations (Lukulu, Matongo and Senanga) along the Zambezi River. Hydrochemistry was employed to determine the composition of the different water sources and identify the genetic link between the local and regional flow of ground water and interactions with the Zambezi River. In addition, water samples collected from various water sources were analysed for stable isotope [deuterium (2H) and oxygen (18O)] to determine the origin and identify the relationships between ground and surface water. Statistical analysis was applied to determine the significance of the correlation between remote sensed data and ground based measurements including, pH, electrical conductivity (EC) and dissolved oxygen (DO).The results of the NDVI map shows a high occurrence of groundwater dependent vegetation downstream of the floodplain. These locations have a shallow depth to groundwater table and other locations had occurances of springs. The average baseflow index (BFI) in five hydrological years from October 2004 to September 2009 shows an average of 46.5 percent baseflow to the river flow across the wet and dry season. Furthermore, baseflow averages up to 90 percent of the flow during the dry season between August to October when the flood water has receeded. The hydrochemistry shows a high concentration in calcium and the bicarbonate ion in both river and groundwater. The water was concluded to be that of a CaHCO3 type. From the stable isotopes the results show recharge from precipitation as values plotted on the meteoric line. Both river and groundwater stable isotopes (δ18O: -57.4 ‰ to 1.4 ‰ and δ2H :-7.5 ‰ to 3.3 ‰ ) had a similar signature indicating that groundwater was discharging into the river channel. Results of statistics between base flow as an index and ground based measurements show a strong correlation between baseflow index (BFI) and dissolved oxygen (DO) indicating that an increase in baseflow increases the dissolved oxygen concentration in the river system. Overall, results show that the lower reach of the Zambezi River channel was a ‘gaining stream’ as groundwater is discharging into the river, whereas the upper reach was a ‘losing stream’ as the river channel tends to discharge into the groundwater. This study demonstrates that the Barotse Floodplain is a proportionally groundwater dependant ecosystem as its functionality in provision of ecosystem products and services requires groundwater. Conservation of this wetland requires prudent protection of groundwater aquifer systems.
- ItemAnalysis of electronic waste management practices in the mining industry of Zambia (case study of first quantum minerals limited and dangote cement Zambia limited).(The University of Zambia, 2022) Kamutumwa, NamatamaThe mining industry in Zambia is one of the sectors that contributes greatly to the country’s economy by contributing greatly to the Gross Domestic Product and according to the latest EITI report, the extractive sector accounts directly for 9.9% of GDP and 78.4% of exports in Zambia. With this at play, there has been a demand to high productivity and this has led to the use of electric equipment such as Computers, printers, electrical lightings and mostly Electronic, remote controlled and computerised heavy equipment machinery during production. Although the use of electronic appliances has great benefit to development of the economy, there has been a great impact on the amount of e-waste being generated as the components in e-waste are toxic and hazardous. This waste has been identified as a problem not just in Zambia but worldwide making the development of an e-waste management system cardinal in any industry. This study employed qualitative methods, purposive sampling techniques and two mining companies First Quantum Minerals Limited (FQML) Kansanshi site and Dangote Cement Zambia Limited (DCZL) were selected as case studies. A regulatory agency Zambia Environmental Management Agency (ZEMA) was also selected. The research methods were used to analyse the management practices of e-waste in the mining industry of Zambia and it was found that the two mining companies were struggling to manage the e-waste generated as there are no e-waste policies or legislation to give guidance on e-waste management practices and they relied on acts such as the Environmental Management Act of 2011 that address hazardous waste management. This study showed that the regulatory agency ZEMA had challenges in conducting sensitization and awareness campaigns and developing of e-waste technical guidelines due to lack of funding. The study concluded that the implementation of e-waste management practices can only be improved through the development of sustainable environmental strategies such as formulation, implementation and enforcement of e-waste management policies and development of e-waste technical guidelines that stress more on handling, storage, collection, sorting, dismantling, transportation in the country. Allocation of funds is needed to develop e-waste technical guidelines and support e-waste management programs such as sensitization and awareness, which have to be implemented, monitored and evaluated within an agreed time frame in these institutions in order to protect the environment from the pollution that comes with this type of waste. Therefore, the study recommended that ZEMA drives the development and implementation of e-waste management policies and legislation with policy makers and develop environmental strategies involving recycling of e-waste and for the mining companies, development of a comprehensive organizational e-waste inventory, development of a sustainable e-waste management system and introduction of EPR (Extended Producer Responsibility) and green procurement.
- ItemGeochemical assessment of an old uchi tailing dump in Kitwe, Zambia.(The University of Zambia, 2024) Muma, StephenThis study investigates the characteristics of soil from an old Uchi Tailing Dump in Kitwe, Zambia, through field sampling and analysis. Soil samples were systematically collected using a grid sampling techniques to inform future environmentally responsible restoration strategies. Particle size distribution was assessed through sieve analysis while X-ray diffraction (XRD) provided insights into the soil's crystalline structure. Results from these techniques, along with elemental quantification using flame atomic absorption spectrometry, revealed a hierarchy of element concentrations in the Uchi Tailing Dump samples: Fe>Cu>Ca>Mn>Co>Zn, with pH ranging from 5.5 to 7.5. Notably, copper (0.56%) and cobalt (0.15%) levels were particularly high. Cuprite was identified as a significant source of copper while iron oxide contributed to elevated iron levels. XRD analysis highlighted quartz, kaolinite and dolomite as the predominant phases, with montmorillonite aiding in pH stability. The study also attributed high calcium content to calcite. Spatial distribution analysis revealed distinct patterns, with elevated copper in the northwest and increased cobalt in the northeast. Both topsoil and subsurface samples exhibited contamination, likely due to anthropogenic influences. The soil was predominantly fine sand (86% sand, 13% clay and 1.4% silt) with a gap-graded particle size distribution. The simulation results from PHREEQC revealed distinct saturation levels for various mineral phases within the tailings, with cupric ferrite (CuFe2O4) at 10.72, cuprite (Cu2O) at 3.08, zincate (ZnSO4: H2O) at -9.54, gypsum (CaSO4: 2H2O) at -4.85 and hematite (Fe2O3) at 13.10. The Geo-Accumulation Index (Igeo) confirmed contamination, particularly in copper (Igeo=5), cobalt (Igeo=2.5), iron (Igeo=0.5) and zinc (Igeo<0). Dust emissions, acid mine drainage, soil degradation and a reduction in biodiversity in the Uchi Stream are significant hazards associated with the Uchi Tailing Dump. In summary, the study underscores the significant pollution and environmental risks associated with the Uchi Tailing Dump, emphasizing the need for ongoing monitoring and remediation efforts to protect the ecosystem and community health in the area. In conclusion, this study highlights significant pollution and environmental risks at the Uchi Tailing Dump, emphasizing the necessity for continued monitoring and remediation efforts to safeguard the ecosystem and community health in the area.
- ItemSpatial and temporal variability of groundwater quality in Barotse floodplain and surrounding areas, western Zambia.(The University of Zambia, 2022) Mweemba, SinkomboGroundwater is one of the most valuable natural resources, which supports human health, economic development and ecological diversity. More than half of the households in Barotse Floodplain and surrounding areas depend on groundwater as the main source of portable water supply. A groundwater quality status review has shown that information and data on groundwater quality in this area is not available. The risk of groundwater contamination is growing due an increase in potential threats posed by anthropogenically induced effects of land use and climate change. It is against this background that spatialtemporal variability of groundwater quality between 2018 and 2019 was undertaken. Purposive sampling was used to collect 50 water samples in dry the season and 69 samples in the wet season for physio-chemical and microbiological analysis. Physio- chemical and microbiological parameters were assessed on-site using potable pH and conductivity meters and at the Geochemical and Environmental Engineering Laboratories from the University of Zambia. At the laboratories, the samples were analysed using standard methods i.e. membrane filtration technique for coliforms whereas chemical analysis was done after APHA(1998). Temporal variation between the dry and wet season was assessed using the ANOVA whereas spatial variation was analysed by comparing the concentration of selected parameters along Lukulu to Mongu, Mongu to Senanga and Kalongola to Kalabo Transect. Characterisation of groundwater type was done with the aid of the Piper diagram. Furthermore, the suitability of water for drinking was assessed by comparing the values obtained in the field and laboratory analysis with World Health Organisation (WHO, 2008) and Zambia Bureau of Standards (ZABS, 2008) limits. It was observed that the concentration of physio-chemical parameters was relatively low and fell within the WHO (2008) and ZABS (2008) guidelines for drinking water except for iron (0.36 to 9.20mg/l), nitrate (10.65 to 30.90 mg/l), sulphate (478mg/l) and sodium (244mg/l). In addition, heavy metals (copper, lead, cadmium, manganese, cobalt, zinc, and chromium) were found to be below detection limits of < 0.006 mg/l. This implies that the current large-scale mining activities taking place upstream in North-western province has not yet affected the groundwater quality of Barotse Floodplain. Sampling points close to communities which have pit latrines and soak-aways within the radius of 30m registered too-numerous-to-count (TNTC). Total coliforms were found in 52% of the sampled water points whereas 30% of the samples registered the presence of faecal coliforms. Statistical analysis of ANOVA for all parameters showed that there was no significant seasonal variation in groundwater quality since the Fcritical was greater than P-Value at 0.05 or 95% level of significance. The seasonal variations observed in microbiological parameters were attributed to anthropogenic causes (human faecal material) resulting from the use of pit latrines and open defecation. Spatial variations between different water points were observed along Lukulu to Mongu, Mongu to Senanga and Kalongola to Kalabo transects. The variations were attributed to the different chemical combination (ionic exchange reactions, mixing processes, evaporation and silicate weathering) stemming from the geology and soil types. Parameters found with concentrations above the standard for drinking water such as nitrates < 0.001to 30.9mg/l, iron (<0.006mg/l to 9.2mg/l), coliforms (0/100ml of water) to Too Numerous to Count (TNTC) were mapped as hot spots. The mean abundance of major cations is, Na+ > K+ > Ca+2 > Mg+2 whereas the major anions are, SO4−2 >HCO3− > Cl− . The hydrochemical facies of groundwater show that Na (Cl) HCO3 and MgHCO3 are the major water type in the study area. The coliforms, nitrate and iron were identified as the major groundwater contaminants. Drivers of groundwater quality variations in the study areas are attributed to both anthropogenic activities and natural processes such as low and high flooding patterns and chemical combination stemming from the geology and different soil type. It is evident from the study that the major contaminants of groundwater in Barotse Floodplain and Surrounding areas are iron, nitrates and coliforms. The concentration of these parameters was considerably above the WHO (2008) and ZABS (2008) guidelines for drinking water. Therefore, they were mapped as hot spots. The study also forms an important baseline from which future changes in groundwater quality will be compared. The study recommends the establishment of a groundwater monitoring network for observation of both the quality and quantity of groundwater in Barotse Floodplain and Surrounding areas.
- ItemDownscaling grace missions groundwater storage estimates using a machine learning model approach for climate change monitoring in the upper Zambezi catchment(The University of Zambia, 2024) Shilengwe, ChristopherThe Upper Zambezi Catchment (UZC) of Sub-Saharan Africa, is among the areas most susceptible to the effects of climate change. Significant challenges for water management are brought on by rising temperatures, shifting rainfall patterns and an increase in the frequency of droughts. In this area, groundwater is an essential resource for ecosystems and human needs. Effective water management, particularly in the context of climate change, depends on groundwater storage (GWS) monitoring. By measuring gravity anomalies, the GRACE and GRACE-FO satellite missions have completely changed how terrestrial water storage (TWS) is estimated globally. However, the use of GWS data for local and regional water management is restricted because of the coarse spatial resolution of these missions. The primary objective of this research was to use open-source remotely sensed data and machine learning (ML) to downscale the GRACE/GRACE-FO GWS estimates to a finer spatial resolution (5 km). Several hydrometeorological variables, including evapotranspiration (ET), land surface temperature (LST), normalised difference vegetation index (NDVI), enhanced vegetation index (EVI), soil moisture and rainfall, were integrated during the downscaling process using the Extreme Gradient Boosting (XGBoost) and Random Forest (RF) algorithms. This method was unique in that it used a time-series split for cross-validation and Z-score normalisation. This made it possible to evaluate the model's performance with confidence. The findings showed that RF regularly performed better than XGBoost in downscaling GWS estimates, yielding more precise predictions because of its capacity to control intricate correlations between variables and prevent overfitting. The correlation coefficients between the coarse input data and the downscaled data in the Barotse sub-catchment for Nash-Sutcliffe efficiency (NSE) were 0.81 (XGBoost) and 0.89 (RF). Segmenting the UZC into smaller sub-catchments improved model accuracy by enabling the analysis to focus on smaller regions with more homogeneous hydrogeological characteristics. In regions with unconfined aquifers, the downscaling greatly enhanced the GWS estimates. The model, however had challenges in areas with confined aquifers, which usually have low hydraulic connectivity and slow recharge rates. One of the study's main findings was that groundwater recharge is greatly decreased below a rainfall threshold of 614.39 millimetres during the wet season. This threshold is essential for anticipating periods of low recharge and planning for water scarcity. The study also showed the extent to which the downscaled GRACE/GRACE-FO data captured drought conditions in groundwater, especially during El Niño years (2015, 2016, 2018, 2019 and 2023), underscoring themissions' potential for drought monitoring. The study found that, on average, GWS decreased throughout the UZC between 2009 and 2023, with anomalies varying from -433 millimetres to +264 millimetres. This research underscores the potential of machine learning in enhancing the spatial resolution and accuracy of GWS estimates, making GRACE/GRACE-FO data more useful for regional water management. These findings have significant implications for managing groundwater resources in the UZC and similar regions experiencing climate variability and increasing water demand.