Civil Engineering Commons^™

Evaluation Of Long-Shore Sediment Transport On The Kunduchi Beach Tidal Flat, Dar Es Salaam, Alfonse Dubi

Tanzania Journal of Engineering and Technology (TJET)

Kunduchi Beach is located approximately IO kilometres north Of Dar es Salaam City on the coasl of Mainland Tanzania. Currents and sediment concentrations were measured using a multi-sensor self-recording current meter. Waves Were measured using pressure gauges. Some physical features were visually measured. The general orientation of the shoreline is 330 degrees and the tidal flat is characterised by ripples. A1 aboul 150 m from the shoreline, ripples are 7-9 cm high and their wavelength is about 40 cm. Closer to the beach, ripple orientation is 350 degrees: ripple height is 5 cm and ripple wave length is 5 cm. …

Prediction Of The Response Of Rectangular Cladding Panels To Wind Loading In The Time Domain, Ambrose Shirima

Tanzania Journal of Engineering and Technology (TJET)

The analysis and subsequent design of cladding panels is traditionally based on quasi-static calculation of the wind loads. Pressure coefficients, which are derived from wind tunnel measurements and a design wind speed, are used to compute the wind loading. The codes of practice give the pressure coefficients and the guidelines of deriving the design wind speed from factors, which are specific to the site namely basic wind speed, topography, ground roughness and height above the ground. The concept of design wind speed is simple but it overlooks the resonant vibrations caused by the wind. The paper discusses a procedure for …

Evaluation Of Pollution Loading Into Msimbazi River By Rapid Assessment And Direct Measurement Methods, J. H. Y. Katima

Tanzania Journal of Engineering and Technology (TJET)

This paper assesses the suitability of Rapid Assessment (RA) methodology as a tool for making an environmental pollution inventory in data poor situation. The RA method was applied to estimate Biological Oxygen Demand (BOD), nitrogen and phosphorous loading into the Msimbazi River in Dar es salaam, Tanzania. The Direct Measurement (DM) was done to validate the results obtained from RA. The methodology is based on estimating waste loads from function variables such as production rate, population, etc. and pollution intensities from domestic, industry and agricultural sources. The incorporation of penetration factors for waste loads reduction refines the assessment procedure. The …

Potential For Use Of Sand In Road Construction In Dar Es Salaam And Coast Regions, Mfinanga A

Tanzania Journal of Engineering and Technology (TJET)

Coarse aggregates for use in road construction in Dar es Salaam and Coast regions are becoming increasingly scarce and expensive while sand, which is cheaper, is readily available in the two regions. This research aimed at evaluating the possibility of using quarry sands in the two regions as a major constituent material in bituminous road pavement layers. First, the use of sand in sand-bitumen bases for low and medium trafficked roads was studied. The study then continued with the preliminary evaluation of the possible use of the sands in hot rolled asphalt mixes. Results show that Mbagala sand can be …

Sustainable Data Acquisition Methods For Road Maintenance Management In Developing Countries, N. K.M. Mushule

Tanzania Journal of Engineering and Technology (TJET)

Whilst it may be argued that manual methods of pavement data collection are subjective, unsafe, involve high personnel costs and have low repeatability, the initial costs of acquiring automated systems coupled with the technology required to operate and maintain them can be prohibitive for most developing countries. Moreover, automatic measurement of surface distress has proved to be a difficult challenge to instrument designers. In many cases, manual methods are the only ones that can be employed. A research project was carried out to design a sustainable data collection scheme for network level management system for developing countries. A simple procedure …

Evaluation Of Water Levevaluation Of Water Levels In Relation To The Design Of Coastal Structures In Tanzaniaels In Relation To The Design Of Coastal Structures In Tanzania, Alfonse Dubi

Tanzania Journal of Engineering and Technology (TJET)

Water levels on the coastline of Tanzania vary under the influence of meteorological conditions (winds and barometric pressure) and the East African Coastal Current, whose strength varies with the monsoon winds. Available tidal information is not enough to warrant statistical analysis for evaluating extreme water levels. The highest mean water springs occur at Bagamoyo and Pangani (3.93 m) and the lowest are found at Lindi (2.96 m). The highest astronomical tide is 3.7 m for Dar es Salaam and 4.6 m for Zanzibar, both of which occur during March/April and November. Measured highest water levels approach 4.80 m for Dar …

Requirements Of A Sustainable Pavement Management System For Tanzania, N. K.M. Mushule

Tanzania Journal of Engineering and Technology (TJET)

Since the introduction of pavement management concepts in mid-1960s, more than three decades ago, a considerable number of Pavement Management Systems (PMS) have been developed and implemented widely in many parts of the world. These systems differ in scope and sophistication. However, in some cases, pavement management systems have fallen into marginal use, if not into complete disuse, because of a number of reasons. One of the major reasons leading to the marginalisation or abandonment of pavement management systems, is the failure of system developers to recognise specific and unique needs of the agency or authority responsible for road management. …

Stress Conditions In The Kilombero Rift, Central Tanzania, A Mruma

Tanzania Journal of Engineering and Technology (TJET)

The ancient and current Stress conditions at the northwestern flank of the Kilombero Rift are assessed in this paper. Neoproterozoic Stresses in the area were associated With 3200/200 trending principal axis of straining in the rocks. Ihis deformation imparted Precambrian ductile gneissic and concordant mineral foliation with attitude Of 0200/3$WNW, 3200/200 trending b•minerai lineation and isoclinal folds With axes trending parallel to the mineral lineation.phanerozoie deformations are mainly of pennvrriasic and Cenozoic periods. Both Of the two episodes Of deformation had constant orientation of princi axes of stresses with trending 0600/020, 02 trending 1600/800 and trending 33 1100. Stress conditions …

Baseflow Separation Based On Storage-Outflow Modelling Of Streamflow Recessions, With Application To Semi- Arid Catchments In Tanzania, S Mwakalila

Tanzania Journal of Engineering and Technology (TJET)

Discharge in many rivers is Often fed by baseflow provided by drainage of the saturated zone in the shallow permeable soils. It is becoming clear that the outflow from this saturated zone is not linear proportional to storage as is commonly assumed in many algorithms. The objectives Of this study theretore, are first to explore the extent to which the assumption of linearity in storage-outflow relationships is valid and secondly to introduce an alternative approach to baseflow separation algorithms for estimating direct mnoff time series. Numerical analysis Of streamflow recessions from the semi-arid catchments of the Great Ruaha basin in …

Some Aspects Of Erosive Waves At Kunduchi Beach, Dar Es Salaam, Tanzania, Alfonse Dubi

Tanzania Journal of Engineering and Technology (TJET)

The area north of the Dar es Salaam City is endowed with beautiful sandy beaches and high concentration or tourist beach hotels that are threatened by coastal erosion. In order to protect the buildings and land, coastal erosion must be controlled by mitigation options that are based on scientific data, wave and current climate along the East African region are generally controlled by the seasonal monsoon winds. During the north-east monsoon period when Winds blow from the Northeast, the wind-generated waves approach the coast from the northerly direction and produce long-shore Currents With a southerly component. During the southerly monsoon …

Efeci's In Reinforced Concrete Due To Environmental Conditions, And Concrete Treatment: A Case Study At The University Of Dar Es Salaam, I Rubaratuka

Tanzania Journal of Engineering and Technology (TJET)

Concrete is produced by mixing together cement, water and aggregates (i. e. sand and coarse aggregates) in specified proportions, It can do well with compressive forces but it is very weak under tensile forces. TO Overcome this problem, steel reinforcement are normally added to produce reinforced concrete which can also withstand tensile forces Experience shows that environmental conditions may have a negative impact On the durability of reinforced concrete structures resulting in development of defects if not properly assessed and appropriate measures adopted to arrest the same at the design and construction stages. The severity of damages for the investigated …

Defects In Reinforced Concrete Due To Environmental Conditions And Concrete Treatment: A Case Study At The University Of Dar Es Salaam, A. Rubaratuka

Tanzania Journal of Engineering and Technology (TJET)

Concrete is produced by mixing together cement, water and aggregates (i. e. sand and coarse aggregates) in specified proportions. It can do well with compressive forces but it is very weak under tensile forces. To overcome this problem, steel reinforcement are normally added to produce reinforced concrete which can also withstand tensile forces. Experience shows that environmental conditions may have a negative impact on the durability of reinforced concrete structures resulting in development of defects if not properly assessed and appropriate measures adopted to arrest the same at the design and construction stages.

The severity of damages for the investigated …

The Development Of Groundwater For Water Supply, C. F. Mhilu

Tanzania Journal of Engineering and Technology (TJET)

ABSTRACT This paper presents results of groundwater investigations carried out at Yombo Dovya Village, Temeke District in Dar es Salaam Region. The study has included hydrogeological and geoelectric resistivity sounding survey data obtained at the test site in Yombo village. The results of this investigation based on the application of vertical electrical sounding probe predictions have indicated the existence of reasonable amounts of groundwater resource for development. To verify these results borehole drilling tests were also conducted at the same site (Borehole No. DSM 79/99), and the results obtained by this method compares very well with those obtained earlier by …

Evaluation Of Extreme Wind Speeds In Relation To The Design Of Coastal Structures In Tanzania, Alfonse Dubi

Tanzania Journal of Engineering and Technology (TJET)

Five distribution functions, FT-I and Weibull with the exponent k = 0.75, 1.0, 1.4 and 2.0 respectively, have been applied to 25-year wind data collected between 1972 and 1996 at Tanga, Dar Es Salaam, Zanzibar and Mtwara Meteorological stations. One maximum value for every year from the full data record was drawn to constitute the annual maxima series for each station. For each of the stations, 2-, 50- and 100-year return wind speeds with corresponding 90% confidence intervals were computed. The distribution functions were fitted to the data by the Least Squares Method. Results from the study show that FT-I …

The Behaviour Of Reinforced Block-Work Walls In Axial Tension, Laurent Shirima

Tanzania Journal of Engineering and Technology (TJET)

Reinforced blockwork with horizontally laid reinforcing bars is used for walls in liquid retaining structures in developing countries. This is the case where, the level of technology in terms of skills and equipment is not in a position to allow successful construction of reinforced concrete walls. Blockwork walls are very sensitive to cracking which cannot be prevented by reinforcement. The major problem for designers is the behaviour of such walls in tension caused by hydrostatic pressure of the stored liquid. This paper reports results of a research work to study the behaviour of reinforced blockwork walls in tension. It was …

Evaluation Of Soil Conservation Measures: A Case Study In Mbinga District, Ruvuma Region, Tanzania, S. Y. Thadei

Tanzania Journal of Engineering and Technology (TJET)

A study on soil conservation measures was conducted in two villages, Tukuzi and Mahenge, in Mbinga District, Ruvuma Region, Tanzania. The results showed that the ngoro farming system was effective in controlling soil erosion by water on both steep and gentle slopes. Sediments collected from ngoro had high concentrations of plant nutrients such as available phosphorus (P), total nitrogen (N), organic carbon (OC) and exchangeable bases. This was probably due to nutrients released from decomposed grass bundles buried in the soil. In preventing soil erosion, ngoro and bench terraces were equally effective, while contour ditches were as effective as ridges …

Mathematical Modelling Of Road Bumps, E. S. Massawe

Tanzania Journal of Engineering and Technology (TJET)

In this paper, a general mathematical model that may be used for construction of a road bump on an inclined road is developed. It is shown that if the parameters for the inclination are set to zero, the resulting model reflects the special case of a flat road. Existing experiences are briefly highlighted and a case study was done on different locations along the University Road to demonstrate the developed model.

Application Of Vibrational Techniques In Determination Of Dynamic Properties Of Agricultural Products-State Of The Arton Of Vibrational Techniques In Determination Of Dynamic Properties Of Agricultural Products-State Of The Art, Silas Kajuna

Tanzania Journal of Engineering and Technology (TJET)

Vibration is one of the techniques employed in the determination of dynamic properties of fruits and vegetables. It entails generation of a mechanical or acoustic vibrational signal which is propagated through the flesh of the agricultural material. A transducer is either attached or held close to the specimen to monitor the propagation of the signal through the specimen. The manner in which the signal is transmitted through the material is analyzed, and the dynamic properties of the specimen which relate to its firmness or its internal being are derived. The technique has been around for the past 30 years or …

Concrete Cracking In Coastal Areas, S. R. Mpinzire

Tanzania Journal of Engineering and Technology (TJET)

The paper discusses cracking and corrosion of reinforced concrete (RC) structures in coastal zones where aggressive action of salt burdened air is the primary cause of concrete deterioration. Case studies are presented, along with discussion of possible remedies including local demolition, reconstruction and epoxy injection as well as concrete treatment.

Technical And Economic Comparison Of Performance Between Farmer And Government Managed Irrigation Schemes In Tanzania: A Case Study Of Kapunga Irrigation Project, D Chemka

Tanzania Journal of Engineering and Technology (TJET)

This paper conwares the perforinance Of governnyent ro fanner-managed irrigation schemes at Kapunga Rice Project in Mbeya Region, south-west Tanzania. The results showed that the farmer-managed irrigation scheme (FMIS) performed better than the government-managed irrigation scheme (GMIS) in attaining good performance. Applicable indicators for farmer-managed irrigation scheme are as shown below with those of government-managed scheme indicated in brackets. Its overall irrigation efficiency was 61' percent (29 percent) average productivity was 3.2 ton/liG (2.2 ton/ha); economic profirability: internal rate of return was 3.2 percent (5 percent), benefit/cost ratio of 0.60 (0.14); while its financial profitability: internal rate of return was …

Estimating The Usle - Soil Erodibility Factor In Developing Tropical Countries:A Case Study In Tanzania, Metthew Mulengeral

Tanzania Journal of Engineering and Technology (TJET)

Developing countries in the tropics are facing more soil erosion problems than the developed temperate countries. These developing countries have no accurate locally applicable equation(s) for predicting soil erosion or for planning and implementation of soil conservation measures. Furthermore, These countries do not have the necessary resources to develop the soil loss prediction equation(s). Existing empirical equations like the Universal Soil Loss Equation (USLE) if modified to suit tropical conditions can be useful a tool in soil erosion control in the region for a foreseeable future. In this paper equations'for estimating the soil erodibility factor in the USLE for tropical …

Sustaina Bility Of Irrigation Schemes For Small-Scale Farmers: A Case Study Of Irrigation Scheme At Buleya Malima, Gwembe Valley, Zambia, Masinja R

Tanzania Journal of Engineering and Technology (TJET)

A study to determine facrors influencing sustainability of smallholder irrigation schemes was carried our a! Buleya Malima, Southern Province, 7_nnzbia. These factors included technical and socio-economic factors. found Out that the technical factors were 26.5, 64.5 and 9.2 percent for application efficiency, tailwater ratio and deep percolation, respectively, indicating that farmers wasted water mainly through tailwater runoff.From socio-economic point of view, the study indicated that the scheme lacked (i) farmer participation in designing and planning operation of the scheme (ii) managerial ability and innovativeness to form their own viable organisation: and (iii) formal training in technical operations of irrigation, infrastructure …

Use Of Dissolved Oxygen Concentration Probes In Biological Wastewater Treatment Plants, S Manyele

Tanzania Journal of Engineering and Technology (TJET)

A study on use Of dissolved oxygen probes (DOP) for measurement Of oxygen concentration in warer and wastewater treatment is presented. The principles Of operation, design considerations and selection criteria for Two types of probes, viz. galvanic and polarographic, are discussed Use of polarographic probes in n rhree-phase fluidized bed bioreactor and in laboratory experiments is presented and discussed. The effect of airflow rate and treatment time on dissolved oxygen concentration was found to be significant. It was found that polarographic probes are important equipment in determining the pollution of the industrial effluents. Finally, the use of the DOC probes …

Experimental Study Of Rural Brick Burning In Iringa And Mbeya Regions, E Mushi

Tanzania Journal of Engineering and Technology (TJET)

In this paper results are presented Of a study conducted between June and December 1997. on nine brick firing kilns in Iringa and Mbeya. The locations for rhe study were Mahenje and Iloniba in Mbeya Region and Igumbilo in Iringa region. Three kilns were investigated in each location. For each kiln the process was followed from the laying Of the bricks into a kiln to the opening Of thc kiln for renu)val Of the bricks in preparation for the selling. Different weights and tenperatures were Taken a,' different times. Firing wet bricks results in consumption of 33.63 % of the …

Development And Evaluation Of A New Soil Erosion- Productivity Index Model (Sepim), Metthew Mulengera

Tanzania Journal of Engineering and Technology (TJET)

A soil erosion-productivity model which considers rhe effect of soil water storage Capacity. crop evapotranspiration, soil chemical and physical properties inrporrantfor Crop growth has been developed. The model is shown to give good predictions and it promises to be an improvement over the former productivity Index (PI). It also promises to give more reliable results than the currently used /nodels which consider only soil water storage capacity and crop e ' 'apotransp iration.

Power Shedding Experiences And Lessons In A Township, Alexander Kyaruzi

Tanzania Journal of Engineering and Technology (TJET)

This paper presents how power shedding by taking out one of the trans- former high voltage fuses causes phase imbalance. And for the same elec- nicc,l energy output generator fuel consuntption with unbalanced phases is 12.5% of The fuel consunwtion with balanced phases. Furthermore it is shown thal energy efficient lighting by use of energy efficient bulbs can reduce load shedding.

Optimum Geometrical Parameters For Prismatic Folded Plate Roofs: System- Atic Search Approach, N Mwitta

Tanzania Journal of Engineering and Technology (TJET)

Folded plate structures have unique structural advantages over conven- nonal beam-and-slab structural forms. Selection of optimum geometrical parameters in design would make folded plate roofs more appealing to the national construction industry in terms ofcost. This paper presents a study on shape optimization of prismatic folded plate roofs for minimum weight of the structure per unit covered area. A computer based systematic search approach has been employed.for the optimization study, while the tranyeer matrix method has been used for analysis. Curves opriinum geometrical parameters versus span have been pre sented for three commonly used shapes of prismatic folded plate roofs. …

Regionalization Of Hydrologic Information In Tanzania (Low Flows), Onyekwuluje C

Tanzania Journal of Engineering and Technology (TJET)

Hydrologic infornjation is required for the planning and design Ofwater resource projects. However, Hydrologic infonnation is always lacking at points of interest. Regionalization is ained at estimating hydrologic infor- mation such as low flow statistics at ungauged sites. Hydrologic informa- tion from 63 catchments in Tanzania has been analysed. In this paper, pooled flow duration curves for 1, IO, 30, 60, and 90 days duration have been established. Regression equations between the low flow indices (i.e. 95 percentile and for a IO day duration, average annual yield (AAY), av- erage daily flow (ADE)) and catchment characteristics were developed. The pooled …

Optimal Capacity Allocation Truck Industry In Tanzania:A Case Of National Transport Corporations(Ntc), R Mgaya

Tanzania Journal of Engineering and Technology (TJET)

This paper tries to examine truck transportation service in Tanzania, particularly, in National Transport Corporation’s subsidiary companies - Regional Transport Companies. It provides an analysis based on operations research approach on resource allocation, specifically, truck allocation, with an aim of trying to minimize running costs and hence improve profits. It is established that there had been higher running costs and hence decline of profits in some Regional Transport Companies due to misallocation of capacity. However, this problem had been compounded by some other factors as discussed in the paper. It is recommended that these Regional Transport Companies and other transport …

Critical Evaluation Of The Effects Of Changes Made To Roughing Filters Of Mpira-Balaka Plant On Its Treatment And Operational Performance, C Zulu

Tanzania Journal of Engineering and Technology (TJET)

Mpira Balaka, a full scale rural water supply project was constructed in Ntcheu, Malawi, in 1988 utilising Slow Sand Filtration (SSF) as the main treatment process and roughing filtration as the pretreatment method,following the promo- tion of this technology by various international institutions. During the rainy seasons, the treatment plant for Mpira Balaka failed to cope with the high raw water turbidity, resulting into very short filter run times and hence also to unavoidable distribution Of very turbid water to the rural communi- ties as a result Of by-passing the filters. Of the fifty or so existing rural projects in …