PhD Theses

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Ageing and axial cyclic loading studies Displacement piles in sands
(University of Dar es Salaam, 2013) Rimoy, Siya Paul
An investigation is presented into the mechanisms governing both the ageing and axial cyclic loading characteristics of displacement piles in silica sands. The thesis considers first the state-of-knowledge regarding the axial capacity of displacement piles in silica sands. Three main areas of uncertainty are identified; the stress regime setup by installation, the mechanisms of ageing that lead to capacity increases with time (set-up), and the effects of axial cyclic loading. New laboratory experiments are then described that involved tests with extensively instrumented 36mm diameter Mini-Imperial College Piles (Mini-ICP) with roughened (Rda ~3.5|im) stainless steel shafts and 60° conical tip bases, that could measure axial loads, and interface radial and shear stresses at multiple positions along their shafts. Less extensively instrumented piles with varying diameters were also tested. Ten installations were made in the 1.2m diameter, 1.5m deep Grenoble- INP calibration chamber. Fresh pulverated sand masses were formed for each installation, which were typically instrumented with multiple commercially sourced (Kyowa and TML) miniature sensors to measure radial, vertical and circumferential stresses in the sand mass during pile installation, ageing, and axial static and cyclic loading tests. Key parameters that might affect pile behaviour were then isolated and considered in turn. The interpretation links the model tests to instrumented field studies and the ageing trends established from a field database. The model piles’ axial cyclic loading responses are analysed by developing cyclic interaction diagrams which are linked to full scale tests and laboratory experiments to identify the key mechanisms governing field cyclic behaviour. The interaction diagrams provide a straight-forward screening tool for addressing axial cyclic loading in practice. Reference is made to more elaborate procedures and to the experiments’ scope for validating numerical models.
Application requirements and selection procedure for urban transport planning models for developing countries
(University of Dar es Salaam, 2007) Bwire, Hannibal
This study develops a unified framework for a model selection process that is suitable to systematically guide the selection decision process of a transport planning model that is most appropriate for a particular planning context. It is motivated by the notion that the ability to judge and select the most appropriate model is one of the most important elements of the contemporary urban transport planning process. Transport models have become important forecasting and decision-support tools in the transport planning process, and their use is well established in developed countries. Most developing countries, however, lack such capabilities mainly due to the lack of quality data and of a sufficient framework for the model selection and application. The lack of quality data is mainly associated with the lack of systematic assessment of data sources and methods of data collection. The lack of a sufficient framework for the model selection is due to the lack of appropriate model application requirements and the lack of suitable model selection process. To provide groundwork for achieving the study objectives, existing literature is reviewed and evaluated. Gaps in strategy for assessment of methods of data collection, in conceptual framework upon which models application requirements are derived and in model assessment and selection methodologies are identified. The study fulfilled these gaps by providing improved methodologies. Application and evaluation of the methodologies on the case studies and the case study area evidences their benefits and their applicability to the urban transport planning process in developing countries.
Assessment of factors influencing electrical fire occurrences in buildings and development of a risk model: case Study of Dar es Salaam city
(University of Dar es Salaam, 2016) Mabulla, Majige Jackson
Populations around the world have been applying mitigation measures of electrical fires in buildings without knowing what the principal factors that influence the fires are. This has made efforts to alleviate electrical fire occurrences in buildings to fail. The main purpose of this research work was to identify the principal factors influencing occurrences of electrical fires in buildings and to develop an appropriate risk model. The principal component analysis methodology was used to identify the principal factors from the identified factors influencing electrical fires in buildings. The results show that short circuit and demographic factors are the principal factors influencing electrical fires in buildings. Short circuits originate from only three areas in buildings which are electrical conducting materials, equipment and appliances; whereas, demographic factors are caused by the population density and characteristics in buildings. From high number of occupants in the building, every occupant has own thinking and desire on electrical use thus accelerating the problem. The developed risk model of electrical fire occurrences in buildings revealed positioning or allowing combustible materials in buildings, for instance mosquito nets, curtains and couches including cobwebs to be close to electrical outlet points, as the critical cause contributing about 70% of the occurrences of electrical fires in buildings. Hence, the recommended method for the population to utilize is just not to put combustible materials in the building close or below the points of electrical ignition potential for instance switches and sockets. Combustible materials should be placed at least 15cm (6 feet) away from these points
Assessment of medical waste management system in Tanzania district hospitals he case of Amana, Temeke and Lingula Hospitals
(University of Dar es Salaam, 2011) Kagonji, Ignatio Simon
The main objective of this study was to Asses the Medical Waste Management System in Tanzanian District Hospitals’’. The perceptions of health workers on medical waste management (MWM) indicated that the waste generation rate ranges from 100 to 1,000 kg/day with different rating between administrators and implementers, which did not match with the actual measured medical waste within the same hospitals studied, making medical waste management difficult. The study showed that about 60% and 80% of health workers segregate their waste. Plastic bins are more utilized at Amana (80%) while metal bins were more in use at Ligula hospital (65%). Container coding and labeling was least implemented (less than 10%) of waste generation points. About 90% of medical waste was transported within the premises manually. The main onsite waste treatment method was medium degree Celsius temperature incinerators (Amana 46% and Ligula 35% of the waste), while the main offsite treatment method used was crude dumping (Amana 74% and Ligula 12% of the waste). The major problems hindering medical waste management were lack of standard MWM procedures (16%); low knowledge and skills on MWM among HWs (16%); and, inappropriate medical waste treatment/disposal technologies in the hospitals (14%). The study revealed that about 60% of health workers (HWs) hale low knowledge on MWM, and lack of administrative documents on MWM was also observed (below 40%). The quantification of medical waste generation observed generation rates of about 2.250 kg/day in Amana and 2,500 kg/day in Ligula hospital, which are very high flom HWs perceptions. The waste generation rate per patient per day was also,high about 1.8 and 2.0 kg/patient.day for Amana and Ligula, respectively: About 6 - 10% of waste generated is left uncollected. The results indicated general waste to have high generation rate compared to other waste types. The results showed chemical, pathological and pharmaceutical waste to have high frequency variations while other categories are evenly generated with little variations. The assessment of treatment/disposal technology and its impact on environment analyzed the incineration process performance at Temeke hospital. Study was conducted for 22 months (N =653 days). The analysis showed that, average sharps waste incinerated were 25% and other wastes were 75%. The average diesel oil used was 30 L/day, and average cycle time was observed to be 3 hrs both being excessively high WHO standards. The financial implication study showed that, a high amount of money about 1300 USD was used per month for fuel only, interfering with hospital plan and budgets. The hospital was advised to install a new incinerator with short incineration cycle time(30 to 45 minutes).and,less fuel consumption (7 to 10 L). The new incinerator was then assessed based on ash characteristics. It was observedthat the pH of ash was more alkaline ranging from 11.0 to 13.0 at 100 g ash/L instead of normal standard 6 to 8. On the other hand, the conductivity of the ash increased with increasing ash concentration ranging from 5.0 to 11 µS/cm alt 100 g ash/L. The investigated tl leachate toxicity of 0.1, 0.1, 0.2, and 0.3 mg/L, respectively, which were observed to be below U.S. EPA limits which are the international standards. It was concluded that, proper medical waste management requires trained/skilled health workers, good appropriate technologies, enough and special designed facilities for collection, storage and transportation and realistic plan and budgets which observe variations in medical waste generation.
Assessment of population and climate effects on the scarce water resources of the limpopo basin, Botswana
(University of Dar es Salaam, 2008) Masaka, Tebogo Larry
vopo Basin of Botswana, in a semi-arid region supports mi-arid region supports more than 60% of elation of Botswana and all administrative bodies hence initiative bodies hence its vulnerability in sustainable water resources. Ever growing water demand growing water demands and their skewed hical distribution in the basin exert immense pressure well immense pressure on the scarce water of the basin. In this study, an assessment on the status assessment on the status of water resources in the Limpopo Basin of Botswana was performed. Thana was performed. This was done by a I mixture of social research and statistical methods to re statistical methods to reveal the alarming 1 the water resources of the basin. An application of the 1 An application of the Mann-Kendall and open estimator were used to assess the trends in hydroceles significant (a=0.05) trends towards declining rainfall amou acted stations in the basin while evaporation showed a the annual values. A climate moisture index (CMI) assess very low CMI values (-0.5 to -1) approaching extreme an n showed declining groundwater level trends except The institutional setup for the water sector is heavily cent end and a majority of water users are still suffering from e' making participatory water resources management a hu iiovernment is not setting a good example through its to solutions to water supply problems. There is a need for not just on paper but also evident on the ground to hell of stakeholders in the Limpopo Basin of Botswana with c:al and administrative levels as they have the mandate to do the trends in hydro climatic data for the declining rainfall amounts were observed adoration showed a trend of a slowly but index (CMI) assessment of the basin approaching extreme aridity. Wel'fields in r level trends except the Molepolole er sector is heavily centralized around the are still suffering from the 'dependency races management a huge challenge. The example through its tendency to favours. There is a need for an IWRM driven t on the ground to help in changing the basin of Botswana with more emphasis at have the mandate to drive the reforms.
Community perceptions of the households’ role on financing public primary education: a case study of Mbeya city council and rural district council in Tanzania
(University of Dar es Slaam, 2010) Anania, Ahadi
The purpose of the study was to explore community perceptions of the households’ role on financing Public Primary Education (PPE) in Mbeya City Council and Mbeya Rural district Council in Mbeya region. The study sample comprised of 96 participants from four public primary schools and the community members around the schools. The study employed both qualitative and quantitative inquiries, guided by a case study design. Data collection was through FGDs, semi structured interviews, documentary reviews and observation schedules. Findings revealed that the investigated communities were aware of households’ role on financing PPE. Secondly, it was noted that the perception of contributing for PPE was negative because they perceived that education was free and that it was the responsibility of the government to finance primary education. Thirdly, their perceptions were mainly affected by conflicting educational policy statements which on one hand insisted on cost sharing and on the other hand claiming free and compulsory primary education. Generally, it was found that the negative perceptions of financing PPE among the community members adversely affected the adequacy of school facilities. The study concludes that unclear policy develops negative perceptions and reduces the extent of contributions for PPE and that poor strategies of involving community members adversely affect their perceptions and subsequently contribution for PPE. The study recommends that educational policies should be clarified and disseminated such that local communities clearly understand them. Further, education stakeholders at lower levels should be fully involved so as to create positive perceptions. Finally, the local government authorities should initiate capacity building programmes to raise community members’ income and train the members of the school committee and local leaders on resource management. It further recommended that similar studies should be conducted in other areas of Tanzania. This may lead to the replication of the findings making diversified results that will enhance comparatives across community settings.
A competitiveness improvement framework for forensic science laboratories (fsls)
(University of Dar es Salaam, 2018) Omari, Gloria Cuthbert
The main factors that affect forensic science laboratory (FSL) competitiveness were identified and ranked through the workers perceptions and the analytical hierarchy process (AHP) for the purpose of establishing measures and methodology for improving FSL competitiveness. Case-file backlogs were identified as one of the cause factors affecting performance, which can be minimized by continued management effort in backlog elimination incorporating methods and procedures identified in the competitiveness improvement framework (CIF). Another cause factor was the turnaround time (TAT), which is the total time interval from when the request for analysis is received until when the results are collected by the client. This study was conducted to establish the baseline data on TAT (between Y2014 and Y2015) to enable implementation of competitive improvement strategies. The analysis time (TAT2) was the longest for all six case-file processing steps. Using Pareto analysis, the three major steps requiring root cause analysis and intervention to minimize the total TAT. The study shows that absenteeism (determined based on hours and days) has also an impact on FSL competitiveness. Supply chain management (SCM) was studied by quantifying the turnaround time for supply chain components in FSL as total supply chain time. Results show also that there is low academic development and longevity among FSL staff which can be minimized by implementing the competitive framework developed. The objective of the study was concluded by developing the competitiveness improvement frame work (CIF) for the FSLs by applying special methodologies in relation to the cause factors.
A conceptual framework for selection of the effective truck-shovel system for bulk material transport in open pit metal mines
(University of Dar es Salaam, 2014) Mafwenga, Samuel Gwamaka
Among the several bulk material transport and handling systems in large scale open pit metal mines, the truck/shovel system competes with overland conveyor belt system in providing minimum cost per tonne of the material transported. For high- volume long-distance travel, overland conveyor systems are proven to be cost- effective compared to truck-shovel systems. However, with effective design (selection and sizing) of the truck-shovel system, especially with the new development of large off-highway trucks of up to 400-ton capacity and shovels of up to 60 cubic metre bucket capacity, the truck-shovel system offers strong challenge to the overland conveyor belt systems. This is mostly due to its increased tare weight, its versatility and its potential to maintain a stable production rate even when few trucks are broken down. The objective of this research work is to develop a conceptual framework for design and selection of the effective truck- shovel system for transportation of bulk materials in open pit metal mines. Several areas of the truck/shovel system were studied. Data on equipment performance characteristics and pit operational conditions were collected over a 12-month period. These data were processed and analysed and construction of the various statistical and empirical models were undertaken. Analysis of these developed models indicated many aspects some of which deviated from their expected performances providing room for improvement of the existing truck/shovel system. The generated models have also provided key statistical distributions, whose cumulative distribution functions can be used for generating input data for each of the truck-shovel system activity or event that is taking place in an open pit.
Crossflow turbine in micro hydropower technology design and performance characterization with respect to internal flow profile
(University of Dar es Salaam, 2015) Kaunda, Chiyembekezo Suzgo
Dam safety analysis using physical and numerical models for small dams in Tanzania: the case of Arusha Region
(University of Dar es Salaam, 2007) Malisa, Johnson
Different failure modes and causes for the failed earthfill dams in Arusha region have been identified. The resulting extent of embankment damage was observed to be significantly larger where average breach top width was found in most cases more than three times the dam height. Even though, there has not be many small dams that has imposed risk to people`s life in the country to date, the loss resulted from the reported incidents is significant in terms of storage loss, embankment damage, environment and farming system destruction. Most of the existing small earthfill dams in Arusha region have been observed to have significant overtopping potential as a result of inadequate spillway capacity. This has been caused but the inherent uncertainty in the flood estimate method used in ungauged areas where hydrological information is scarce and changes in the catchment characteristics are significant. A method has been proposed and applied toassess and evaluate overtopping potential of a small earthfill dam (s) located in ungauged catchment as well as assessment of damage and danger in the downstream surface erosion resulted into stair-stepped multiple overfalls which finally merged into a single main upstream-migrating headcut. The rate of upstream headcut migration has been evaluated based on measured material properties, hydroulic and dam breach parameters. The important preliminary procedures for dam safety improvement have been highlighted to provide preliminary guidelines in the design, operation and maintenance.
Densification, relaxation, and combustion characteristics of densified Biomass fuels: a comparative study with wood combustion.
(University of Dar es Salaam, 2001) Rajabu, Hassan M.
Densification of loose biomass waste such as agricultural, forest and industrial residues to form Densified Biomass Fuels (DBF) is an attractive option in areas where these resources remain unutilized. The potential of DBF to substitute fuelwood or coal in industrial combustion systems depends on how closely its handling and combustion behaviour match the existing facilities. In this work, experiments were conducted to study densification, relaxation, and combustion characteristics of rice straw and sawdust DBF. Experiments on wood combustion were also conducted for comparison to DBF. Densification tests were performed in uniaxial closed-die mode. Die diameters of 2.5 and 3.8 cm were used with die pressure up to 134 MPA. Results showed that an exponential relationship in the form: P=Ae(Bp), seems to best represent the uniaxial densification process for the material tested. Where: P is the die pressure, and p is the density of DBF. The values for coefficients `A' and `B' depend on die size, material type, and storage relative humidity. The relaxation behavior of DBF was studied in low, medium, and high, relative humidity conditions. DBF made of rice straw showed 52-68% increase in length in the pressure range tested, which is 6-18% higher than for sawdust. DBF from the larger diameter die showed 3-9% higher expansion compared to the smaller die. DBF showed higher percentage increase in length when stored in high humidity conditions. The change of moisture content of DBF during storage delays the stabilization period and increases their expansion considerably. Combustion tests were carried out in an isothermal thermogravimetric analyser. Results demonstrate that, during pyrolysis the cylindrical particles of both DBF and wood loose mass in a thin reaction zone. DBF were found to expand during combustion by up to 50% of its original volume. The anisotropic properties in wood have an influence on the direction of volatile gases coming out of the particle during pyrolysis. Model predictions show that drying and pyrolysis overlaps. Model predictions on the advancement of pyrolysis zone in radial and axial directions, and burning rate of the particle are in good agreement with experiment results.
Determination of viable connectivity technology for e – learning in Tanzania: Case Study of Rural Secondary Schools
(University of Dar es Salaam, 2012) Simba, Fatuma
In response to different development challenges, Tanzania is striving to achieve her fourth attribute of the National Development Vision, i.e. to have a well educated and learning society by the year 2025. The earmarked approach is to integrate Information and Communication Technology (ICT) in education system (e-learning), in order to improve teaching and learning processes, hence provision of quality education. However, Tanzania is challenged by lack of ICT infrastructures in rural areas, which affects integration of ICT in education. This thesis presents a research work to determine a cost-effective and performance efficient connectivity technology for rural secondary schools to access e-learning resources. The research surveyed wireless technologies, in order to identify potential broadband access technologies suitable for rural areas of the developing countries. Because ICT is a very dynamic sector, the identified technologies were compared by using conceptual framework to study their sustainability and thereafter, analyzed by using techno-economic approach to determine a feasible and cost-effective option. Results show that, a third generation (3G) Universal Mobile Telecommunications System (UMTS) operating at 900MHz is a feasible and cost-effective connectivity technology for rural areas of Tanzania. Furthermore, the research employed a simulation modeling approach to study traffic differentiation and priority scheduling mechanisms in providing Quality of Service (QoS) for e-learning applications in UMTS networks. A simulation model of the UMTS network has been developed and used to study performance of e-learning applications as perceived by users. Simulation results showed that, UMTS network configured with traffic differentiation and priority scheduling can guarantee delivery of e-learning services with the required QoS. The Public Private People's Partnership (PPPP) model is proposed by this research as an implementation strategy for sustainable broadband rural connectivity solution.
Developing an assessment model for pre – implementation of enterprise resource planning system in Tanzania.
(University of Dar es Salaam, 2018) Mdima, Baraka
The Enterprise Resource Planning (ERP) systems is closely linked to organisational competitiveness. This study investigated the implementation of ERP projects with focus on the development of an approach for assessment of the pre-implementation phase of organisations for successful ERP projects. A purposely selected sample of organisations at various phases of implementation of ERP systems were used in the study. The Critical Success Factors (CSFs)for implementation of ERP projects were confirmed through statistical approach using the Confirmatory Factor Analysis. The fuzzy ANP Based ERP pre-implementation model for the assessment of the pre–implementation was developed using the CSFs and fuzzy ANP approach. Followed by the development and programming of the DSS Enabled ERP Pre-Implementation tool using the C#, MATLAB and SQL Database under Visual Studio Express Environment. The test results trailer manufacturer, real estate corporation and a banking institution indicated that good level of ERP pre-implementation readiness score of 0.5774(i. e 57.74%) for trailer manufacturer; unfavorable level ERPat 0.3829(i.e 38.29%) for a real estate corporation and good level at 0.7575 (i.e75.75%)within recommended Consistency Ratio(CR) between 0.08 and 0.1. The researcher concluded that: first, CSFs are important in establishing the status (whether ready or not) of an organisation prior implementation of ERP system. That the decision to implement an ERP system introduces organizational change to the enterprise with enterprise architecture regarded as strategic tool for managing organisational change with focus on the alignment between ERP software and core business processes. Secondly, the assessment of the pre – implementation phase of organisations involves complicated computations related multi-CSFs network that may be solved by a developed fuzzy ANP Based ERP Pre–implementation model. Thirdly, the research developed the DSS enabled ERP Pre-implementation Tool to handle complex and multi criteria decision making challenge.
Developing performance prediction model for improvement of irrigation projects: the case of Tanzania
(University of Dar es Salaam, 2015) Matekere, Eliakim Chitutu
This research is a continuation of efforts to find ways to improve irrigation projects. The performance of many irrigation projects implemented in the past has been low in many countries, Tanzania being one. The research involved an in-depth analysis of how irrigation projects work, identifying the source of implementation problems, the variables affecting implementation and related methods, and suggestions for performance improvement strategies. The survey data were collected through follow-up data, case studies of seven irrigation projects that were accompanied by expert interviews, and a survey of 94 commentators involved in various stages of project implementation. Statistical analysis was performed using statistical and non-statistical methods for qualitative analysis. The analysis also involved the development of a code of calculation done in a data mining system using a computer program called "Cubist". It has been noted that the source of problems in project performance relates to various stages of project implementation. These include limited funding for projects, and inadequate water management and irrigation infrastructure. In terms of the indicators of: production, irrigated area, and irrigation efficiency, the variables that affect the performance of projects are related to the inputs and processes and those that come from the various implementation processes. The standards achieved in various indicators, when applied in accounting principles, can be the basis for the improvement of irrigation projects. Such strategies include timely and efficient availability of resources, water and specialized expertise, and good management. This study proposes to experiment with the use of a mathematical formula created by using rice. In addition, unlike the rice crop, the application of this method of calculating the principle of calculation should also apply to other crops, as well as to include the performance criteria of the people. This will be a way to identify the specific causes of the new performance criteria.
Development and application of a GIS-based regional hydrological variability and impact assessment system (RHVIAS) for Southern Africa Region
(University of Dar es Salaam, 1999) Berhanu, Fanta Alemaw
Local or regional water resources planning and management is a complex problem. Clearly, hydrologic aspects constitute the major component. In addition, hydrological assessment of the existing and the future water-resources availability of a region is an important aspect. Assessing the environmental impact of the indisputable possible global climate change on regional water resources is another fundamental global concern. This calls for the development of a distributed hydrological model that accounts for the spatial variation and regional distribution of the various natural resources and environmental assets of a region. For this purpose, a GIS-based regional hydrological variability and environmental impact assessment system (RHVIAS) is developed. The system links the different components for analysis of regional water resources availability, variability and environmental impact assessment (EIA) of possible climate change on water resources at a regional scale. The system developed in this work has three components: variability analysis subsystem (VAS), a hydrological modeling subsystem (HMS), and an environmental impact assessment subsystem (EAS). The Southern African subcontinent, the SADC region, is considered for this study. The variability analysis subsystem (VAS) is composed of a system of time series models for hydrological variability analysis. It constitutes sub-modules for: (i) studying the annual and seasonal river runoff variability of 665 rivers, (ii) detection of possible climate change using a century-record of annual precipitation and temperature, and (iii) attribution study of climate change in terms of El Nino effects on river runoff variability using correlation analysis. VAS is externally coupled with ArcView~GIS for portraying the spatial coherence of identified temporal variability in the river runoff regimes. The hydrological modeling subsystem (HMS) is a system comprising a distributed GISbased hydrologic model (DGHM). It considers the geo-referenced distributed ground and satellite-based information such as soil, vegetation and other hydro-climatic information. DGHM simulates regional water balances such as runoff, soil moisture acid evapotranspiration for any grid, using GIS based temporal information and coupling with stochastic weather generation models (WGMs) for weather disaggregation. The WGM for rainfall has been built from a network of 760 rain gauge stations consisting of daily rainfall of length 2-91 years recorded in this century throughout the Southern African region. Both descriptive ability and predictive ability statistical tests have revealed the potential applicability of the model to generate rainfall at any selected grid in the region. The environmental impact assessment subsystem (EAS) constitutes a module for EIA of climate change on the water resources. It uses DGHM and it is externally coupled with a set of global climate models (GCMs) and simulated regional climate change scenarios. A coupling procedure is formulated to make a link in EAS between the GCM derived climates and DGHM through WGMs. Three GCMs are coupled in EAS selected from a suite of 14 GCMs tested - based on the IPCC 1992 emissions scenario (IS92a) and associated global warming with respect to the baseline 1961-90 climatology of the region. The selected GCMs represent relatively wet, dry and moderate scenarios, and they are the Oregon State University (OSU) model, the Hadley Centre 1994/95 model (HADCM2), UK Hadley Centre 1992 model (UKTR). Each component of RHVIAS, viz. VAS, HMS and EAS, has been tested individually, and finally integrated as interactive user-interface package to undertake an integrated water resources assessment. The approach used in VAS provided an excellent environment for undertaking variability analysis in temporal horizons and portraying attributes in a spatial context using GIS tools, for 665 gauged catehments in Southern Africa. River runoff declines since mid of 1970s have been prevalent in central and southern part of the SADC region. In the 20th century, temperature rises at a rate of 0.09° C per decade, and rainfall variation of mainly ±20% have been investigated. A correlation analysis of seasonal El-Nino/Southern Oscillation (ENSO) indices (that occurred since mid of 1950s to 1998) and annual discharge of selected rivers in the region is carried out. It reveals that a significant variance is accounted for by the ENSO episodes that suggest possible El Nino contribution to the natural variability of runoff. The HMS provides an excellent tool for simulating regional water balances at georeferenced grids of 0.5° resolution covering the region. It simulates the 1961-90 monthly runoff, evapotranspiration and soil moisture regimes of the SADC region. EAS provides a means of portraying regional water resources availability for the current and post-climate change conditions as a result of the simulated set of regional climate change scenarios predicted by GCMs. The 1961-90 average mean annual runoff from the land catchments in Southern Africa, generated using the developed model, in the region is about 151 mm per year, although there is a significant inter-regional variation among the SADC countries. Surface water availability in the region will be less reliable, and runoff changes are expected to be within ±20% in the 2050s; however, decision-makers should,be aware of the sub-regional variations and uncertainties associated with GCM-based climate change projections in formulating strategies to cope with the risks of climate change. Integrated water management at the river basin level remains the key action to alleviate water scarcity in the region. Potential actions to mitigate fossil fuel emissions such as increased agro-forestry and energy conservation & efficiency, employment of renewable energy systems and use of alternative fuels are suggested. Measures taken to reduce GHGs simultaneously reduce local and regional pollution. Designing the right response, in the region or a particular country, however, presents a tough challenge; while benefits accrue to the whole world, the costs accrue to the country where the investment or policy change takes place. The author has explored the implication of global efforts in abating or mitigating climate change - from the formation GEF to the Kyoto Protocol - and the provision of the UNFCCC framework for countries to address the treat of climate change.
Development and application of decision support tools for lake Victoria sub-catchments
(University of Dar es Salaam, 2013) Mohamed, Hussein Gadain
Lake Victoria is an important hydrological system that serves its bordering countries and the Nile basin. Its sub-catchments are one of the most densely populated areas in East Africa. This has led to mounting pressure on the available land and water resources, resulting into increased water demands, lake level fluctuations, forest degradation and floods. Pressure on these resources and others is expected to increase even further. The objective of this study was to develop and apply decision support tools for the Lake Victoria sub-catchments. Hydrological models have received increasing recognition in recent years as effective tools in supporting water resources management decisions. Four models that operate independently, and an impact assessment model have been developed in the form of decision support tools using results of remote sensing analyses, GIS technology and hydro-meteorological data. These are: LVIC_SRM (Lake Victoria Spatial Rainfall Model), LVIC_RRM (Lake Victoria Rainfall-Runoff Model), LVIC_IFS (Lake Victoria Inflow Forecasting System), LVIC_WBAL (Lake Victoria Water Balance Model), and LVIC_IAM (Lake Victoria Impact Assessment Model). Various hydrological analyses were performed and outputs obtained using these models. Using LVIC_SRM by incorporating satellite and observed rain gauge data into the krigging models improved rainfall estimation when compared to single variable krigging. A relation between rainfall over the lake and its basin was built and has improved significantly with use of satellite data. LVIC_WBAL model established that rainfall constitutes 85% of the total lake inflow making the water level highly sensitive to changes in rainfall. Earlier and recent level rise were captured with reasonable accuracy and were attributed mainly to increase in rainfall in the area. The future behaviour of the lake was predicted using a stochastic data generator, and that future lake level will not follow a particular trend. Using satellite images the study demonstrated that, stream flow in the Mara catchment has changed leading to increased peak flows and there is likelihood of occurrence of flash floods during wet season and lowered flows during dry season. The decline in natural vegetation has been attributed to deforestation and increased agriculture among others. With the help of the inflow forecasting system, potential flood areas in Nyando river can be delineated and at risk population be alerted in advance and evacuated. Further, the impact on lake hydrology was assessed using development scenarios of agriculture, water supply and increased outflow. Through LVIC_IAM the study concluded that, irrigating 3% of arable lands in the lake basin has higher impacts on lake hydrology when compared to water withdrawal for domestic purposes in Tanzania. Provided reasonable data availability, the impact model could be useful tool for water development in the lake basin. The models are specific decision support tools for Lake Victoria sub-catchments and the study recommends their wider application in other tropical catchments with similar characteristics.
Development of a decision support system for the rufiji river basin - Tanzania
(University of Dar es Salaam, 2003) Yawson, Daniel Kwesi
Three stand-alone Decision Support System (DSS) models have been developed at three critical locations within the Rufiji River Basin in Tanzania. The models are the Usangu Basin Model (UsaBaMod) for the headwaters of the Great Ruaha River, which is the main contributor to the Mtera-Kidatu Reservoir System, the Mtera- Kidatu Simulation Model (MteKid) for the optimal operational procedure of the reservoir system, and the Rufiji River Basin Flood Warning System (RBFWS) for the Rufiji floodplain and the Delta. For the UsaBaMod, dry season irrigation was found to be the main cause of the drying up of the Great Ruaha River among the numerous possibilities considered, and that if the dry season irrigation abstractions are restricted to crop water requirements, for example, instead of the constant abstraction methods being employed, then the river would be able to sustain flows during the dry season. Investigations about the possible cause of the failure of the reservoir system have shown that the actual amount of water that was being released from the Mtera Reservoir as spill must have been much higher than what had been recorded. It was also evident from the investigation that while Mtera Reservoir was “struggling” to get refilled in certain years the Kidatu Reservoir recorded large amounts of spill more enough to bring the Mtera Reservoir to its full condition. RBFWS in a form of a user-friendly computer package to generate flood forecasts within the Rufiji River at Stiegler’s Gorge and at Mloka as well as showing the extent of flood inundation in the floodplain with the corresponding flow magnitude had also been developed.
Development of a hybrid water defluoridation technology in groundwater supply systems
(University of Dar salaam, 2013) Thole, Bernard
Research was carried out to develop a hybrid water defluoridation technology with natural bauxite, gypsum and magnesite to ensure that changes in; pH, colour, hardness, residual that occur when water is defluoridated with each of these materials are within WHO recommended standards. Batch and fixed bed experiments were carried out with the raw and calcined materials and their composites. Bed Depth Service Time (BDST) design model and Empty Bed Residence Time (EBRT) optimisation model were employed to determine optimum fixed bed parameters. The materials were calcined at eight temperatures through range 150 oC to 500 oC. XRF showed that the raw bauxite was predominantly (30.33%), gypsum was mainly (28.09%) and magnesite was mainly (34.57%). The 200 oC calcine composite of mass ratio 3:2:1 (bauxite: gypsum: magnesite) obtained optimum qualities. Mixed sorption mechanisms were observed with Langmuir and Temkin being pronounced for different calcines indicative of monolayer sorption and chemisorption, respectively. Critical bed depths were 6.56 and 7.71 cm for raw and the 200 oC calcined composites with operating lines and , respectively where is adsorbent exhaustion rate (g/l) and is empty bed residence time (s). A 200 oC calcine composite filter of bauxite, gypsum and magnesite in the ratio 3:2:1, respectively is viable for defluoridation. BDST and EBRT can be used to upscale its fixed bed.
Development of a model for assessing organizational innovation on research and development institutions in Tanzania
(University of Dar es Salaam, 2016) Kerefu, Lawrence J
‘Innovate or die’ a slogan which indicates the growing significance of innovation in business. In developing countries such as Tanzania, R&D institutions are the main reliable formal sources of innovation. There are various types of innovation including product, process, marketing and organizational innovation (OI). Few researchers for R&D activities in developing countries focused on products and processes only while the influence of OI to the innovate performance of R&D institutions is enclosed in a black box. Furthermore, as R&D activities lie at the heart of business development, strategies and innovation, it is important to have an ability to a33c33 R&D’s organizational capability to innovate in a diverse way. Literature reviewed show that the available tools have limitations in assessing OI in R&D institutions particularly in the least developed countries. Therefore the main objective of this research was to develop a model for assessing OI in R&D institutions in Tanzania. The research was divided into research design, data collection, analysis and conclusion. A model, with four hypotheses which were highly statistically significant at 1% significance level, was developed. Employing survey methodology and a sample of 56 R&D institutions in Tanzania, and using the Model, it was established that OI has a significant positive impact on the Innovative performance of R&D Institutions. The Model was tested in selected R&D institutions and the obtained results showed to be consistent with the established organizational innovation factors from the developed hypotheses. It was thus concluded that the model can be used to assess OI in R&D institutions in Tanzania and increase research research results uptake by industries. Also it can be replicated to other sectors.
Development of a model for optimising the variations on forecasted construction cash flows: the case of building projects in Dar es Salaam – Tanzania
(University of Dar es Salaam, 2018) Malekela, Kimata Newman
The contingency sum is provided as the ceiling amount for absorbing variations that may occur on planned budget during execution of construction projects. However, there have been significant variations on forecasted construction cash flows which exceed the contingency sum provided. This study is therefore aimed to develop a model for optimising the total variations on overall forecasted construction cash flows within the contingency sum provided during execution of building projects in Tanzania. Specifically, this model is used to minimise those variations within the contingency sum provided in building projects. Data were collected through questionnaire from 284 building contractors in Dar es Salaam. In addition, documentary review of historical data from contract documents of 40 recently completed building projects was conducted and supported by interviews to project participants and self-auditing to contract documents. Eight major risk factors were identified, but the leading four risk factors with their overall relative contributions in causing variations are unclarity of clients’ requirements (0.249); errors in project documents (Bills of Quantities) (0.187); consultants’ lack of experience and technical skills (0.131); and poor/incomplete design (0.130). The study concludes that the model of this study can minimise more than 60% of total variations planned to occur in execution of building projects. It is therefore recommended that the model solutions should be used in establishing the proactive risk measures for controlling variations caused by risk factors on forecasted construction cash flows of building projects.

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