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A Fuzzy Inference System for Modelling Streamflow: Case of Letaba River, South Africa.
(Elsevier, 2008-07-10) Katambara, Zacharia; Ndiritu, John
Stream flow modeling of Letaba River in South Africa is complicated by several factors including the existence of dams and other storage structures whose releases are intermittent and based on rules of thumb depending on the irrigation demands and the need to maintain the flow required in the Kruger National park (KNP). The KNP is located about a hundred kilometers downstream of the main storage and water flows through an alluvial aquifer where complex surface–groundwater interactions occur. Farmers abstract water intermittently along the route directly from the river or indirectly from the alluvial aquifer complicating the flow patterns even more. Consequently, the stream flow series in the river shows very little similarity to what would be considered as natural. The actual abstractions are not measured and only monthly estimates of the abstractions currently exist. Like in many other basins in South Africa, stream flow, groundwater level, rainfall and evaporation data in Letaba is sparse and not very reliable. The Takagi–Sugeno fuzzy inference system using subtractive clustering, an approach which is capable of dealing with vague and inadequate information and data has therefore been used to develop a daily stream flow model for Letaba River. In order to take into account the spatial variability and to maximize the use of the available data, the model is applied in a semi-distributed manner consisting of three river reaches. The shuffled complex evolution (SCE-UA) optimizer has been used to calibrate the model. Six years of data from March 2002 to April 2008 has been used for model calibration and verification. To maximize the Nash-Sutcliffe efficiency, the minimum number of clusters required was found to be 10 for 1000 data points in calibration. An analysis of the location of the cluster centers, the coefficients relating the inputs with the simulated stream flow, and the degrees of membership indicates that no single cluster can be associated to the simulation of a specific hydrologic process or component of the stream flow hydrograph (e.g. high flows or low flows). The fuzzy model does not therefore provide any evidence that it is not a pure black box. The Nash–Sutcliffe efficiency results obtained in calibration and verification showed average values of 0.658 and 0.535 with poor values on the first river reach. Very low percent bias values averaging to _0.4% and _2.7% in calibration and verification are obtained highlighting the model’s potential for applications where mass balance considerations are most important.
A TIME-DEPENDENT GREEN ELEMENT FORMULATION FOR SOLUTION OF POTENTIAL FLOW PROBLEMS IN 3 DIMENSIONAL DOMAINS
(University of the Witwatersrand, Johannesburg, 2010) Nyirenda, Edwin
In this work we develop a generalised methodology for the solution of the time dependent second order parabolic differential equation of potential flow in heterogeneous media using the Green element method. Parabolic differential equations are one class of differential equations, the others being elliptic partial differential equations and hyperbolic differential equations. Since elliptic differential equations generally arise from a diffusion process that has reached equilibrium, they can also be solved using the methodology developed, and represent a simplification because of the steady state situation. Potential flow problems are of great interest in many engineering applications such as flow in aquifers, heat transfer processes, electro-magnetic field problems, etc. Traditionally, the finite difference method and the finite element method have proved to be powerful techniques to solve such potential flow problems, but each has limitations and challenges which have led to continued research in numerical methods. The finite difference method is more applicable to domains with regular boundary, and the finite element method, though extremely versatile, exhibits unacceptable inaccuracies with coarse meshes, thus requiring fine meshes with the associated high computation costs. In view of some of the limitations with these earlier methods, several numerical schemes are now being developed as viable alternatives to these conventional methods. Among such methods are the boundary element method, the finite volume method, and the analytic element method. The boundary element method has been particularly promising because of its domain-reduction feature and the second order accuracy that can generally be achieved. The domain-reduction feature of the boundary element method, though achieved for restricted class of problems, lends it to efficient grid generation algorithm, while its second-order accuracy ensures reliability and consistency of the numerical solutions.-iv _________________________________________________________________ The boundary element method in its original formulation is unable to deal with heterogeneities in the domain. For physical problems, especially in groundwater flow, heterogeneities and anisotropy are a natural and frequent occurrence, and this has fuelled research into boundary element techniques that are capable of accommodating these features. The Green element method is one technique which is based on the boundary element theory and which has been proven to be very effective in handling heterogeneities and anisotropy in 1D and 2D domains. However, development of techniques to implement the Green element method in 3D domains has remained largely unexplored. This work represents an effort in this direction. We have investigated the adoption of the general tetrahedral and hexahedra elements for use with the Green element method, and found that the large number of degrees of freedom generated precludes retention of the internal normal direction as in 1D and 2D formulations. Furthermore, some of the complicated surface and domain integrations with these elements can only be addressed with quadrature methods. The compatibility issues that arise between element faces, which present considerable challenges to multi-domain boundary element techniques, are innovatively addressed in the computer code that has been developed in this work. The Green element method is implemented for steady and time-dependent problems using regular hexahedra elements, and the results show that the performance is slightly better than the results obtained using FEMWATER. FEMWATER is an established finite element method software. No attempt is made to compare the computation efficiencies of the 3D GEM code and FEMWATER because the two codes were not developed on a common platform.
Adopting the system of rice intensification (SRI) in Tanzania: A review
(Mbeya University of Science and Technology Journal of Research and Development (MJRD), 2013-07-02) Katambara, Z
The demand of water for irrigation purposes in Tanzania outstrips the amount of water available for irrigation and other demands. On the other hand, the demand for more food to feed the growing population is increasing, calling for the need to have technologies and farming prac- tices that ensure more food production while minimizing water uses. Rice is among cereal crops grown in Tanzania, and it can assist in meeting the food demand for the nation. Majority of rice producers in Tanzania and Sub-Saharan Africa (SSA) are subsistence farmers and they practice continuous flooding, a technique that requires much water. In addition to using large amounts of water, the conventional practices of growing paddy using local varieties transplant- ing process are implemented when seedlings are more than 21 days old, and 3 - 4 seedlings are transplanted in one hole. This practice re- sults in low yields, and low water productivity and water use efficiency. The system of rice in- tensification (SRI) on the other hand, is a prom- ising new practice of growing paddy rice that has proven to be very effective in saving water and increasing rice yields in many parts of the world. SRI practice is spreading fast and it has been adopted in many countries. The SRI prac- tice has been introduced in Tanzania during the last 3 years as such it is not widely practiced. This paper reviews SRI practice at global, re- gional and country (Tanzania) level, and evalu- ates the challenges, opportunities and implica- tions for its adoption in Tanzania. Knowledge gaps at each level have been identified and dis- Copyright © 2013 SciRes. cussed as well as suggestions for researchable areas.
Adopting the System of Rice Intensification (SRI) In Tanzania: A Review
(SciRes., 2013-06-02) Katambara,Zacharia; Kahimba, Frederick C.; Mahoo, Henry F.; Mbungu, Winfred B.; Mhenga, Fikiri; Reuben,Paul; Maugo, Muyenjwa; Nyarubamba, Anthony
The demand of water for irrigation purposes in Tanzania outstrips the amount of water available for irrigation and other demands. On the other hand, the demand for more food to feed the growing population is increasing, calling for the need to have technologies and farming practices that ensure more food production while minimizing water uses. Rice is among cereal crops grown in Tanzania, and it can assist in meeting the food demand for the nation. Majority of rice producers in Tanzania and Sub-Saharan Africa (SSA) are subsistence farmers and they practice continuous flooding, a technique that requires much water. In addition to using large amounts of water, the conventional practices of growing paddy using local varieties transplanting process are implemented when seedlings are more than 21 days old, and 3 - 4 seedlings are transplanted in one hole. This practice results in low yields, and low water productivity and water use efficiency. The system of rice intensification (SRI) on the other hand, is a promising new practice of growing paddy rice that has proven to be very effective in saving water and increasing rice yields in many parts of the world. SRI practice is spreading fast and it has been adopted in many countries. The SRI practice has been introduced in Tanzania during the last 3 years as such it is not widely practiced. This paper reviews SRI practice at global, regional and country (Tanzania) level, and evaluates the challenges, opportunities and implications for its adoption in Tanzania. Knowledge gaps at each level have been identified and discussed as well as suggestions for researchable areas.
Afractional-Order Trypanosomabrucei Rhodesiense Model With Vector Saturation and Temperature Dependent Parameters
(SPRINGER, 2020) Helikumi, Mlyashimbi; Kgosimore, Moatlhodi; Kuznetsov, Dmitry; Mushayabasa, Steady
and density of tsetse fly population. Precisely, ectotherm performance measures, such as development rate, survival probability and reproductive rate, increase from low values (even Temperature is one of the integral environmental drivers that strongly affect the distribution zero) at critical minimum temperature, peak at an optimum temperature and then decline to low levels (even zero) at a critical maximumtemperature. In this study, a fractional-order Trypanosomabrucei rhodesiense model incorporating vector saturation and temperature dependent parameters is considered. The proposed model incorporates the interplay between vectors and two hosts, humans and animals. We computed the basic reproduction number andestablished results on the threshold dynamics. Meanwhile, we explored the effects of vector control and screening of infected host on long-term disease dynamics. We determine threshold levels essential to reducing the basic reproduction number to level below unity at various temperature levels. Our findings indicate that vector control and host screening could significantly control spread of the disease at different temperature levels.
An Artificial Neural Network Model of the Crocodile River System for Low Flow Periods.
(Wits, 2009-01-21) Sebusang, Nako M.
With increasing demands on limited water resources and unavailability of suitable dam sites, it is essential that available storage works be carefully planned and efficiently operated to meet the present and future water needs.This research report presents an attempt to: i) use Artificial Neural Networks (ANN) for the simulation of the Crocodile water resource system located in the Mpumalanga province of South Africa and ii) use the model to assess to what extent Kwena dam, the only major dam in the system could meet the required 0.9m3/s cross border flow to Mozambique. The modelling was confined to the low flow periods when the Kwena dam releases are significant. The form of ANN model developed in this study is the standard error backpropagation run on a daily time scale. It is comprised of 32 inputs being four irrigation abstractions at Montrose, Tenbosch, Riverside and Karino; current and average daily rainfall totals for the previous 4 days at the respective rainfall stations; average daily temperature at Karino and Nelspruit; daily releases from Kwena dam; daily streamflow from the tributaries of Kaap, Elands and Sand rivers and the previous day’s flow at Tenbosch. The single output was the current day’s flow at Tenbosch. To investigate the extent to which the 0.9m3/s flow requirement into Mozambique could be met, data from a representative dry year and four release scenarios were used. The scenarios assumed that Kwena dam was 100%, 75%, 50% and 25% full at the beginning of the year. It was found as expected that increasing Kwena releases improved the cross border flows but the improvement in providing the 0.9m3/s cross border flow was minimal. For the scenario when the dam is initially full, the requirement was met with an improvement of 11% over the observed flows.
An Investigation for Energy Sustainability in Cement Industries in Tanzania: The Case of Mbeya Cement
(Technische Universität Berlin Institut für Energietechnik, 2017) John, John Pius
Cement production processes are facing crucial sustainability issues such as inefficient en‐ ergy and raw material use, product supply, production cost and environmental pollution. High energy and material use dominated by inefficient characteristics of cement production processes, in turn, lead into depletion of non‐renewable resources, increased production costs as well as environmental degradation due to emissions. The main objective of the study was to investigate performance of cement industry in Tanza‐ nia relative to sustainable energy utilization. Most of past researches have evaluated the per‐ formance of cement production processes using first law of thermodynamics alone (mass and energy balances) with the objective of improving energy efficiency. Although this ap‐ proach sheds light on the question of improvement of energy use in the processes, it has some limitations. The limitations are imposed by the internal irreversibility due to combustion and other physico‐chemical nature of reactions dominating the whole processes. The current emerging approach, which overcomes limitations imposed to the first law approach is ex‐ ergy‐based method, relatively new in evaluation of performance of cement production pro‐ cesses. However, owing to complexity of cement production processes, applying an exergy‐ based method manually is very difficult and complex. The current study proposes combined approach of exergy based method and modeling as well as simulation. The model was successfully developed, validated using real plant data and was used to predict the performance of the cement dry rotary kiln system of Mbeya Cement production processes. Data obtained from modeling and simulation were further used to evaluate the performance of processes, individual components, sub‐systems and overall kiln system at large using exergy based method. The approach not only simplifies the analyses but also gives detailed insight of real processes, source and type of real imperfections, its magnitudes and how imperfections can be minimized. Major findings indicated that the rotary kiln sub‐systems and the overall kiln system have poor exergetic performance, suggesting that potential for improvement exists. The overall exergy efficiency of the kiln system is around 33 %. Also results indicated that the rotary kilns have the lowest exergetic efficiency of about 14 % followed by the clinker cooler with exergetic efficiency of about 41.11 %. The highest source of irreversibility encompassed chemical reactions, especially calcination and clinker burning processes with exergy destruc‐ tion of 2,813.75 kJ⋅kgcl−1 and 1,148.17 kJ⋅kgcl−1. Results from parametric analysis suggested that if measures for improvements of processes, components and sub‐systems are taken, a significant amount of fuel and specific energy could be saved. Furthermore, it was confirmed that if the avoidable exergy destruction is minimized, processes, system components and sub‐systems performance could be improved from exergetic point of view.
Application of Conceptual Model in Developing the Jangwani Mini-Hydropower Plant in Ruvuma Region, Tanzania
(Mbeya University of Science and Technology Journal of Research and Development (MJRD), 2021-10-28) Katambara, Z
The Seventh Sustainable Development Goal is on ensuring access to affordable, reliable, sustainable and modern energy. The promotion and the use of renewable energy sources is inevitable. Within the spectrum of renewable energy sources, there are the mini-hydropower plants which have been reported to have the potential to provide for rural electrification. The existence of reliable flowing water necessitates the investment in mini hydropower for off grid systems. To prove the viability of such schemes, a hydrological analysis of the Mtandazi River was conducted. The Australian Water Balance Model, a conceptual model, was used to model the stream flows using the California Method. The results suggest that for 95% exceedance, the flow is 1.62 m3/s. The flows will enable the installation of the Jangwani mini hydropower plant to generate 226.7 kW of electricity in Ruvuma Region, Tanzania. The study recommends for the conservation of the catchment for the sustainability of the flows.
Application of the RUSLE model to estimate sedimentation in the Lwanyo Reservoir in Mbarali District Mbeya– Tanzania
(IWA Publishing, 2025) Moshi, Baraka Moses; Katambara, Zacharia; Lingwanda, Mwajuma
The constant increase in the global population is proportional to the increase in basic human needs associated with environ mental degradation. Sedimentation in water bodies poses socio-economic challenges as it lessens the storage capacities. The RUSLE model expresses the effect of sedimentation in the Lwanyo reservoir sub-catchment. Key factors influencing sedimentation include: maximum erosivity factor (R) is 421.39 (MJ mm ha 1 h 1 yr), the soil erodibility factor (K) is 0.071, the topographic factor (LS) due to catchment topography is 9.086, the vegetation cover and management factor (C) is 0.1045, and the conservation practice factor (P) is 0.14. The RUSLE model estimates soil sediment loss to be 3.977 tonnes/ha/year, as the average annual soil loss for the Lwanyo sub-catchment area is 39.6 km2. This value indicates that for every hectare, the average annual soil loss is 1.004 10 3tonnes/year, with silt as the dominant soil sediment being eroded. If no intervention measures are implemented, the sediment load could reach 119.31 tonnes over 30 years, reducing the reservoir’s storage capacity by 68.177 m3. Reducing human activity in the catchment and promoting afforestation to mitigate sedimentation can help increase soil stability and reduce erosion.
Assessment of Siltation Impact and Mitigation Strategies for Sustaining Storage Capacity in Lwanyo Dam, Tanzania
(MJRD, 2024-09-03) Baraka M. Moshi; Zacharia Katambara,; Mwajuma Lingwanda
The ongoing generation, transportation, and deposition of silt in the Lwanyo Dam has significantly reduced the storage capacity of the Lwanyo Reservoir, originally constructed to support irrigation and the surrounding ecosystem. The objective of this paper was to assess the extent of siltation in Lwanyo Dam, evaluate its impact on the dam's storage capacity, and propose measures to mitigate silt accumulation. The upstream catchment area, approximately 39.6 km², includes around 128,991 m² allocated for rain-fed crop cultivation and 5.89 km² for pastoral activities. Frequent overtopping of the reservoir has been observed, largely due to siltation reducing its live storage capacity. In the reservoir trial pits were excavated and assessed, and they indicate that average silt layers range in thickness from 0.54 m to 0.98 m per rainy season. The deposited material consists of a silt layer from 0 to 540 mm, followed by an intermediate clay layer from 540 mm to 3100 mm. The impounded silt depth was measured at 1270 mm, with an estimated siltation volume of 58,349.4644 m³. The reservoir's original storage capacity of 210,153 m³ has been reduced by 27.765% due to siltation. The reservoir’s structural design inadequately addresses silt management, lacking both silt flushing tunnels and upstream silt check dams. The analysis indicates that storage capacity decreases by 3.085% annually, and if this linear trend continues without any intervention measures, the dam will lose all storage capacity within 24 years. The study recommends urgent measures to mitigate silt accumulation.
Assessment of Spatial Water Quality Variations in Shallow Wells Using Principal Component Analysis in Half London Ward, Tanzania
(Scientific Research Publishing, 2025-02-21) Matungwa, William; Katambara, Zacharia
Groundwater is a crucial water source for urban areas in Africa, particularly where surface water is insufficient to meet demand. This study analyses the water quality of five shallow wells (WW1-WW5) in Half-London Ward, Tun duma Town, Tanzania, using Principal Component Analysis (PCA) to iden tify the primary factors influencing groundwater contamination. Monthly samples were collected over 12 months and analysed for physical, chemical, and biological parameters. The PCA revealed between four and six principal components (PCs) for each well, explaining between 84.61% and 92.55% of the total variance in water quality data. In WW1, five PCs captured 87.53% of the variability, with PC1 (33.05%) dominated by pH, EC, TDS, and microbial contamination, suggesting significant influences from surface runoff and pit latrines. In WW2, six PCs explained 92.55% of the variance, with PC1 (36.17%) highlighting the effects of salinity, TDS, and agricultural runoff. WW3 had four PCs explaining 84.61% of the variance, with PC1 (39.63%) showing high contributions from pH, hardness, and salinity, indicating geological influences and contamination from human activities. Similarly, in WW4, six PCs ex plained 90.83% of the variance, where PC1 (43.53%) revealed contamination from pit latrines and fertilizers. WW5 also had six PCs, accounting for 92.51% of the variance, with PC1 (42.73%) indicating significant contamination from agricultural runoff and pit latrines. The study concludes that groundwater quality in Half-London Ward is primarily affected by a combination of surface runoff, pit latrine contamination, agricultural inputs, and geological factors. The presence of microbial contaminants and elevated nitrate and phosphate
Assessment of Temporal Variations in Shallow Well Water Quality Using Graphical Analysis and Water Quality Index in Half-London Ward, Tunduma, Tanzania
(Mbeya University of Sience and Technology, 2025-03-01) William, Matungwa; Katambara, Zacharia
Shallow wells are vital for water supply in regions lacking centralised systems, but they are highly susceptible to contamination from anthropogenic activities and natural processes. This study investigated seasonal variations in water quality from five shallow wells in Half London Ward, Tunduma, Tanzania, over a 12-month period to assess biological, chemical, and physical parameters, to identify contamination drivers, and to propose sustainable management solutions. Using WHO and EPA guidelines, monthly water sampling was conducted for 12 months from June 2022 to May 2023. Parameters analysed included Faecal and Total Coliforms, Nitrate, Phosphate, Total Iron, Biological Oxygen Demand (BOD), pH, Electrical Conductivity (EC), Turbidity, Total Dissolved Solids (TDS), and Total Suspended Solids (TSS). The National Sanitation Foundation Water Quality Index (NSFWQI) was employed to classify seasonal variations in water quality. Results revealed significant seasonal trends. Microbial contamination peaked during the rainy season, with shallow well WW3 and WW5 recording faecal coliform levels of 5 CFU/100 ml and total coliforms of 18 CFU/100 ml, exceeding WHO and East African Standards. Phosphate levels in shallow well WW4 and WW5 exceeded the threshold of 2.2 mg/l, attributed to agricultural runoff. Elevated iron concentrations (1.85 mg/l) in WW4 reflected natural geological leaching. BOD and turbidity increased during wet periods due to organic pollutants and sediment influx, while physical parameters such as pH and TDS remained within permissible limits. The NSFWQI ranged from "Excellent" (18.6) in shallow well WW5 during winter to "Medium" (65.4) in shallow well WW3 during summer, highlighting contamination risks from surface runoff and poor land management. The study concludes that rainfall and proximity to pollution sources significantly impact shallow well water quality. It recommends implementing community-driven sanitation measures, protecting shallow wells, and conducting routine monitoring. These findings provide a framework for improving groundwater quality for domestic use in urbanising regions globally.
Assessment of the Influence of Tip Speed Ratio, Solidity and Reynolds Number on the Aerodynamic Performance of Selected Locally Fabricated Wind Turbines in Tanzania
(The University Of Dar Es Salaam, 2019) Kachira, John Peter
The sites with good wind energy conditions in Tanzania have motivated some local craftsmen to manufacture wind turbines using local and imported materials. However, some studies have shown that these turbines have low performance. In this study, theoretical approach has been carried out to assess the influence of TSR, solidity and Re on the aerodynamic performance of nine selected locally fabricated wind turbines in Tanzania. Three manufacturing centers namely, Dar es Salaam, Singida and Makambako were selected and three different HAWT rotor blades from each center were put under testing. Their respective rotor radii and chord widths were measured and used to determine their TSR, solidity and Re. The measured TSRs were 0.63, 0.70, 0.79, 0.90, 1.57, 2.09, 2.51, 3.14, and 4.19. Unlike 4.19, the rest values were below the recommended range between 4 and 10 for which WECS are recommended to generate large scale electricity. The respective measured solidities were, 0.90, 0.10, 0.13, 0.17, 0.18, 0.28, 0.88, 1.07 and 1.22. These solidities were found to be above the proposed range between 0.01 and 0.05 for which WECS are designed to generate large scale electricity. These high solidities lead into high torques reducing rotational speed of the WECS. The measured Res were 86,030, 99,265, 100,589, 102,574, 125,736, 138,972, 145,589, 145,589 and 152,207. These Re values are below the standard Re which is at least 6 110 implying that they exhibit turbulent flow with high level of drag coefficient that influences low performance of the WECS. The 3 - bladed wind turbine from Matiya in Singida was found to have good TSR of 4.19 though its solidity was found to be above the recommended standard values range. It needs an optimization of its chord and radius to improve its efficiency. Therefore, these wind turbines can only generate small scale electricity due to their poor aerodynamic performances
Characterisation of Titanium Alloy Processed By Constrained Bending and Straightening Severe Plastic Deformation
(The University Of Johannesburg, 2020) Mwita, Wambura Mwiryenyi
Most Severe Plastic Deformation (SPD) processes lack both the capability for continuous process and the homogeneity of tailored material properties in processed samples. These challenges have limited the adaptation of SPD technology to process titanium alloys for biomedical and structural applications. This thesis presents microstructural and mechanical characterization of Ti6Al4V titanium alloy processed by a Constrained Bending and Straightening (CBS) SPD technique. The proposed CBS method was intended for a continuous process of titanium sheets with improved magnitude and homogeneity of the entailed strain, hardness and tensile properties. The CBS process tool was designed and fabricated in the University of Johannesburg workshop. The tool was used to process Titanium Alloy Grade 5 (Ti6Al4V) sheets at a combination of (2, 4, 6) passes (N) and (6 mm, 12 mm) feeds (F) designated as N2F6, N4F6, N6F6, N2F12, N4F12 and N6F12. Sub-samples were cut from the processed sheets. The samples were prepared, and their respective microstructural analysis, hardness and tensile tests were performed. A numerical model for the CBS process was built and simulated with ABAQUS Standard Finite Element Analysis (FEA) method. The model was used to predict the magnitude and the homogenity of the Effective Plastic (EP) strain, the tensile yield strength and the hardness of the material. The simulation results were validated with the experimental data. The experimental results showed that vi comparing with the As Received (AR) samples, the processed samples showed a decrease in the average grain size from 10µm to 3µm, together with the formation of new finer subgrains. The tensile strength, the yield strength and the hardness of the material increased by 29.3%, 33.5% and 24.4%, respectively. The values of these material properties at the F6 feed were higher than those at the F12 feed. The simulated results showed that the maximum mean EP strain of 2.87 induced in the material correlated with the highest strain homogeneity that corresponded to the lowest Coefficient of strain Variation (CV) of 18.9%. A comparison of the results from both methods on the yield strength and the hardness showed a direct correlation at the N2 and the N4 passes. A relative inverse correlation was observed at the N6 pass due to the saturation of the material hardening and the onset of yielding. Results from this study have quantitatively shown that the CBS method performed well the intended work. However, this method needs desirable improvement at a commercial level before it is viable as an alternative method for the continuous production of the titanium alloy sheets enhanced with the homogeneous microstructural and mechanical properties
Characterizing Hydrological-Sensitive Areas of The Kinyerezi River SubCatchments in Dar Es Salaam, Tanzania Using The Topographic Index Approach.
(IWA Publishing, 2023) Swilla, Livingstone; Katambara, Zacharia; Lingwandaa, Mwajuma
Several areas experience frequent floods due to anthropogenic activities. Among them, is the Dar es Salaam city, which experiences frequent floods along the Msimbazi River, whose flows originate from different tributaries including the Kinyerezi River. This study aims to evaluate the hydrological-sensitive areas of the Kinyerezi River sub-catchments using topographic index values (λ*) that enable the identification of areas with a higher probability of generating surface runoff. A digital elevation model was utilized to delineate the Kinyerezi River sub-catchment characteristics using ArcGIS 10.4. Soil infiltration rates (Ks) on selected open places were determined using a Guelph permeameter. Soil particle size distributions were analyzed and the λ* values were evaluated. The results showed the particle size distribution contains sand and silt-clay ranging from 46 to 84% and 16 to 53%, respectively. The Ks ranged from 0.6 to 7.8 mm/h while the sub-catchment KS3 scored the highest λ* value of about 10.7. Hence, there is a higher probability for generating surface runoff. Sub-catchment KS16 scored the smallest λ* value of 5.7, perceived to generate less surface runoff. Low-impact development practices capable of capturing runoff and enabling infiltration, evaporation, and detention should be employed in sub-catchments with higher λ* values.
Chemical Characterization of Pumice Material Sourced from Mbeya, Tanzania
(MUST, 2025-02) Nyangi, Patrice
Pumice, a lightweight volcanic material abundantly available in Mbeya, Tanzania, is underutilized and often discarded following excavation activities. In most construction projects within the region, conventional materials like clay soil, river sand, normal-weight aggregates, and cement are pre-dominantly used, leaving the potential of pumice largely unexploited. This study presents a comprehensive chemical characterization of pumice sourced from two locations, MUST main campus (Sample A) and Wimba (Sample B), to assess its suitability as a supplementary cementitious material (SCM). Energy Dispersive X-ray Fluorescence (EDXRF) analysis revealed that Sample A contained 70.3% SiO₂, 17.9% Al₂O₃, and 3.53% Fe₂O₃, while Sample B had 71.3% SiO₂, 17.3% Al₂O₃, and 3.38% Fe₂O₃. The combined SiO₂, Al₂O₃, and Fe₂O₃ content for both samples exceeded the 70% ASTM C618 threshold for pozzolanic materials, confirming strong pozzolanic properties. Additionally, K₂O was 5.21% in Sample A and 5.05% in Sample B, while CaO was 0.667% and 0.763%, respectively.SO₃ was detected at 0.448% (Sample A) and 0.482% (Sample B), and TiO₂ at 0.528% and 0.507%, respectively. Na₂O and MgO were not detected. The high levels of SiO₂ and Al₂O₃ suggest strong pozzolanic properties, while the low CaO content indicates that pumice would function primarily as a pozzolanic additive rather than a primary binder. Consequently, these findings confirm that pumice is better suited as a supplementary cementitious material (SCM) and filler rather than a complete replacement for cement. By partially replacing cement with pumice, it could be possible to reduce the carbon footprint, contributing to more sustainable construction practices.
Comparative Study of Bachelor of Civil Engineering Curricula in Higher Learning Institutions in Tanzania: A Systematic Review
(IISTE, 2021-10-31) Mhando, Yusuph B.; Kifanyi, Gislar E.
This paper compares the curricula of Bachelor degree in the field of civil engineering. This helps improving the quality of curriculum that generates demand driven engineering graduates with an equal competency in the context of labour market. Descriptive survey was adopted, and a checklist of courses from purposively selected higher learning institutions was used. Constant comparative analysis to categorize types of information investigated was adopted. Findings indicate that Bachelor degree programme in civil engineering at Dar es Salaam Institute of Technology (DIT), Mbeya University of Science and Technology (MUST) and St. Joseph College of Engineering and Technology (SJCET) has duration of 3 or 4 years depending on the entry qualification of the student, whereas at Arusha Technical College (ATC) it takes 3 years to complete the programme. On the other hand, inconsistency on the number of courses and academic loads offered in these institutions was revealed. The study suggests a joint development of curricula for training programmes. This could help trainers, researchers, curricula developers and policy makers to harmonize and minimize discrepancies of the curricula contents of the same programme offered in different institutions.
Contamination and Human Health Risk due to Toxic Metals in Dust from Transport Stations and Markets in the Kumasi Metropolis, Ghana
(Kwame Nkrumah University of Science and Technology, 2019) Rweyemamu, Almachiusi. Rwegasira
Heavy metals are very harmful to human health and their increasing contamination of dust in the urban areas calls for serious attention to them. The aim of this study was to determine the concentrations and assess the potential human health risk associated with exposure to selected heavy metals in dust from transport stations and markets within the Kumasi metropolis, Ghana. A total of 50 dust samples from transport stations and markets were collected by sweeping ground surface dust and analyzed for Arsenic (As), Cadmium (Cd), Chromium (Cr), Copper (Cu), Nickel (Ni), Lead (Pb), Zinc (Zn), Iron (Fe), Mercury (Hg) and Antimony (Sb). The concentrations of Hg were determined by Atomic Absorption Spectrophotomery using a Lumex RA-915M Zeeman Automatic Mercury Analyzer while the levels of other metals were determined by using X-ray Fluorescence analyzer (Niton XL3t GOLDD+). The concentrations of As, Cd, Cr, Hg, Cu, Ni, Pb, Zn, Fe and Sb in transport stations ranged from below detection to 9.66, below detection to 37.13, below detection to 260.11, 0.01 to 0.62, below detection to 143.77, below detection to 47.62, below detection to 61.73, 48.89 to 218.61, 3768.97 to 40936.07 and below detection to26.01 mg/kg respectively.The concentrations of As, Cd, Cr, Hg, Cu, Ni, Pb, Zn, Fe and Sb in markets ranged from below detection to 6.20, below detection to 14.61, below detection to 232.90, 0.01 to 1.38, below detection to 181.85, below detection to 44.79, below detection to 72.10, 59.29 to 293.68, 8283.66 to 34953.63 and below detection to 21.72 mg/kg respectively. The study revealed no significant difference between the mean concentrations of heavy metals in dust from transport stations and markets at 95% confidence limit of T-test analysis (p>0.05). The mean geo-accumulation, contamination factor and modified degree of contaminations indicated that dust from both transport stations and markets were moderately to extremely polluted by metals compared to their abundance in the dust of the control site vi (KNUST Botanic Gardens). Mean enrichment factors indicated that metals were highly enriched in the dust and originated from anthropogenic sources. Pollution load index which ranged from 1.39 to 12.55 for transport stations and from 1.48 to 15.62 for markets revealed high pollution load. The hazard index (HI) and carcinogenic risk index (CRI) were used to assess human health risk. Hazard indices for all the metals were less than the safe limit of 1, signifying no potential non-carcinogenic risk for both children and adults. Exposure to multiple metals was observed as a major concern of non-carcinogenic risk to children. Among the metals assessed for carcinogenic risk, the CRI of Cd in both transport stations and markets exceeded the safe limit of 1x10-4 for children. Health risk assessment indicated children to be highly exposed to heavy metals in dust via ingestion compared to adults. This study observed high pollution load of heavy metals in the studied areas and therefore appropriate measures need to be taken in order to manage the pollution
Developing a Surface Water - Groundwater Interaction Model for Letaba River System in South Africa
(KATAMBARA, 2006) Katambara, Z.; Ndiritua, J.G.
There is a constant increase in water demand and a pressing need to conserve the environment in the Letaba River system. This is leading to a situation where the demand for water may have outstripped the capacity of the existing resources to sustainably meet them. In the past dams were constructed and boreholes drilled as a strategy of reconciling demand and supply and this is evidenced by the numerous dams and boreholes in the Letaba River system. There are five major dams; three of which have a capacity exceeding 60 million cubic meters and also more than 3000 boreholes in the river basin. Currently, all the dams are stressed and the releases from Tzaneen Dam, intended to meet the water requirements of downstream users including Kruger National Park fail to meet these requirements substantially. Although these demands are high and probably exceed the system’s capacity, it is likely that the reliability of supply can be improved significantly if the surface water - groundwater (sw/gw) interactions within the basin are modelled comprehensively and then incorporated into system operation. This paper reports on an ongoing development of a sw/gw model of the Letaba River System. The model development intends to maximize the use of the relevant available information and data and recognizes the existence of an interaction zone which forms a major link of many of the processes that will be included in the model. It has been found that the scale of monitoring processes in the river system is inadequate and is a significant constraint to the development of the model that is expected to impact on the level of confidence in model implementation and application. Incorporation of uncertainties will therefore be an integral part of the modelling.
Developing a Surface Water - Groundwater Interaction Model for Letaba River System in South Africa
(Mbeya University of Science and Technology Journal of Research and Development (MJRD), 2013-02-06) Katambara, Z; Ndiritua,G. J
There is a constant increase in water demand and a pressing need to conserve the environment in the Letaba River system. This is leading to a situation where the demand for water may have outstripped the capacity of the existing resources to sustainably meet them. In the past dams were constructed and boreholes drilled as a strategy of reconciling demand and supply and this is evidenced by the numerous dams and boreholes in the Letaba River system. There are five major dams; three of which have a capacity exceeding 60 million cubic meters and also more than 3000 boreholes in the river basin. Currently, all the dams are stressed and the releases from Tzaneen Dam, intended to meet the water requirements of downstream users including Kruger National Park fail to meet these requirements substantially. Although these demands are high and probably exceed the system’s capacity, it is likely that the reliability of supply can be improved significantly if the surface water - groundwater (sw/gw) interactions within the basin are modelled comprehensively and then incorporated into system operation. This paper reports on an ongoing development of a sw/gw model of the Letaba River System. The model development intends to maximize the use of the relevant available information and data and recognizes the existence of an interaction zone which forms a major link of many of the processes that will be included in the model. It has been found that the scale of monitoring processes in the river system is inadequate and is a significant constraint to the development of the model that is expected to impact on the level of confidence in model implementation and application. Incorporation of uncertainties will therefore be an integral part of the modelling.

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