Research Repository :: Browsing by Author "Mulungu, Deogratias M. M."

Browsing by Author "Mulungu, Deogratias M. M."

Now showing 1 - 11 of 11

Analysis of Institutional Arrangement for Greywater Management in Unplanned Settlements of Kinondoni Municipality Tanzania
(IWA Publishing, 2015) Ndunguru, Teresia W.; Mulungu, Deogratias M. M.
Greywater (GW) may contain pathogens and organics thereby calling for its management. Institutional arrangement (IA) is the heart of planning, coordination and management of initiatives. Analysis of IA is key for determination of what could be rectified within organisations based on the existing structure, resources, strategies, data and information, stakeholder participation and involvement, policy and by-laws. Kinondoni municipality has the largest population of the three municipalities in Dar es Salaam city. In this study, the IA for GW management in Kinondoni municipality was analysed using weighted strengths, weaknesses, opportunities and threats (SWOT). The weights for the SWOT criteria were obtained from field interviews with households and key informants, and then integrated using expert judgement. Overall, from the analysis matrix, the SWOT was towards weaknesses (73%) and opportunities (60%).Weaknesseswere largely due to internal factors, otherswere lack of horizontal and vertical coordination, accountability, and stakeholder participation. With respect to GW management, these results revealed that there is inadequacy in the existing institutional structure, which accelerates poor performance in GW management practices in Kinondoni municipality. Accordingly, this study proposed an IA that induces stakeholder involvement and participation, accountability mechanisms and collaboration between departments in GW management
Applications of the Soil Water Assessment Tool (SWAT) in Simiyu River Catchment
(2005-11-14) Mulungu, Deogratias M. M.; Mtalo, Felix W.; Bauwens, Willy
The physically based Soil Water Assessment Tool (SWAT) model is applied on the Simiyu river catchment at Ndagalu outfall, Tanzania. Input data are spatially distributed data set such as topographical, land cover and soil data, climatic and river flow time series data. The model was calibrated for the period 1970-1974 based on the availability of coinciding climatic data and validated in the period 1976-1983. The calibration involved fine-tuning the land coversoil parameters to match the observed discharge at Ndagalu flow gauging station. The weather generator tool of the SWAT was used to fill in the missing climatic data and enabled flow simulation in the periods with missing data. Several model fit techniques and water balance matching techniques were used to assess model performance. Results and analysis was presented to show model performances in calibration and validation periods. During model set-up it was found that the land use (especially vegetation types) classification was a sensitive issue for the river flow estimation. The study identified optimum parameters for better discharge simulations. However, since some model parameters were obtained manually by fine-tuning, in future study the more physical basis of the parameters need to be considered. Also, the analysis of observed and estimated hydrographs showed that the rainfall data used is not representative and more rainfall data is required especially in the headwaters of the catchment so as to have better rainfall representation, which may produce better model fits. Considering the good results of SWAT in this study and comprehensiveness of the model in land surface processes representation, the model is very promising for land and water management studies and expected to give valuable information to land and water resources managers.
Appraisal Study to Select Suitable Rainfall-Runoff Model(s) for the Nile River Basin
(2005) Bashar, Kamal E.; Mutua, Francis; Mulungu, Deogratias M. M.; Deksyos, T.; Shamseldin, A.
This paper presents an appraisal study to select a suitable model(s) that can be used in forecasting flows in the rivers of the Nile basin. Flow forecasting is an important step in river basin management in particular and water resources management in general. River flow models are used as components in actual flow forecasting schemes. They are also used in providing for efficient operation of storage reservoirs. Usually, flow forecasts are obtained in real time by transforming the input into a discharge using models. These forecasts may subsequently be modified or updated in accordance with the errors observed in the previous forecasts up to the time of making the new forecast. The system analysis or black box approach depends on a prior assumption of flexible linear and time invariant relationship the expression of which can be obtained by the application of systems analysis approach to records. The conceptual model provides an alternative approach in which the input-output transformation goes through a series of steps. In this appraisal study, systems and conceptual modelling techniques are applied to lake Victoria catchments (Simiyu, Sondu and Nzoia), Awash and the Blue Nile catchment up to Eddeim of the Ethiopian high lands. The models were applied in non-parametric and parametric forms. Parameter optimisation is carried out by ordinary least squares, Rosenbrock, Simplex and genetic algorithm. The areal rainfall which is the main input to these models was estimated using arithmetic mean. However, attempts to estimate the areal rainfall by the Thiesen polygon method was made but the improvement in the model performance can not justify the amount of work involved in making Thiesen’s estimate. It is shown that the simple assumption of linearity is not adequate in modelling the rainfall runoff transformation. However, in catchments which exhibit marked seasonal behaviour good results can be obtained with Linear Perturbation Model (LPM) which involves the assumption of linearity between the departures from seasonal expectations in input and output series. The application of the GFFS (collection of systems and conceptual models) software proved to be possible with variable efficiencies in the Nile River basin. The LPM in non-parametric or parametric form, the LVGF model the ANN and the SMAR model can be used to forecast (reproduce). In catchments that exhibit marked storage effects e.g Sondu and Nzoia LPM and SMAR performed better than the other models. In Simiyu river it seems that the transformation can not be done under the assumption of linearity and hence the ANN performed better. Within the range of the tested models LPM was found to be the best candidate model that can forecast the flows under a wide range of conditions ranging from marked seasonality to marked storage effects accounting for more than 90% of the initial variance.
Comparison of Forest Canopy Interception Models Combined with Penman-Monteith Equation.
(2002) Mulungu, Deogratias M. M.; Shiiba, Michiharu; Ichikawa, Yutaka
Three models of interception process: Rutter model with Deardorff's power function, Deardorff model and Modified Kondo model, each in combination with Penman-Monteith equation applied to the same climatic forcing over the year of simulation were compared. The modification of the Kondo's model done in our study includes the water balance component, between storms evaporation and transpiration including the power function, storage changes and the canopy drainage. The comparison was meant for assessing the simple Modified Kondo model developed in Japan and demonstration of the importance of the power function. The Penman-Monteith equation was the kernel for determination of evaporation and transpiration rates. Its use in this study was proposed because it has been widely used in Japan and in experimental sites and therefore can be used as a basis for comparison. Since much interest was on net rainfall, the control volume for the water accounting was between top of the canopy and above the ground surface and hence does not include soil moisture and transpiration. Results showed that forest canopy evaporation ranged from 22 to 29% of gross rainfall. Much model prediction differences were observed in winter, with lower rainfall intensity where wet canopy storages or rainfall did not meet the potential (atmospheric) evaporation demand. The annual net rainfall and transpiration ranged from 71 to 78% of gross rainfall and from 727 to 733 mm respectively. The adopted power function had significant impact on transpiration rate and small impact on evaporation rate for the Modified Kondo model. The Modified Kondo model predicted fairly close to the two models and therefore can be used for providing hourly input into hydrological models. The differences in the predicted hydrological fluxes resulted from the different model for mulations especially throughfall coefficients and drainage functions.
Constructed Wetland at the University of Dar Es Salaam
(Elsevier, 2000) Mashauri, Damas A.; Mulungu, Deogratias M. M.; Abdulhussein, B. S.
Following lack of investment in wastewater treatment, high investment and maintenance cost, conventional treatment systems have not been used in Tanzania. On the other hand, cost effective wastewater treatment methods like the use of septic tanks, soak pits, drainage fields and waste stabilization ponds are widely applied. One of the methods of achieving compliance using conventional treatment systems at low cost, producing treated water pollution free and fostering a community responsibility for wastewater treatment involves the use of natural or constructed wetlands. To date, no wetlands have been used for treating wastewater in Tanzania. Therefore in an attempt to promote the use of constructed wetland for wastewater treatment, a horizontal flow constructed wetland at the University of Dar es Salaam was commissioned for treatment of wastewater effluent from the University waste stabilization ponds (WSP).This paper presents results obtained from a constructed wetland (CW) installed at an outlet of the WSP of the University of Dar es Salaam. The field tests were conducted at low and high filtration rates 0.27 m/h and 2.3 m/h respectively for a period of 4 weeks. Treatment effectiveness was evaluated which indicated high mean removal efficiencies; 80% for SS, 66% for COD, 91% for faecal coliforms (FC) and 90% for total coliforms (TC) achieved at the low filtration rate. Thus, wetlands if properly designed, operated and maintained can provide an efficient and economical means of upgrading the quality of secondary treated wastewater to an acceptable level.
Integrated Flood and Drought Management for Sustainable Development in the Kagera River Basin
(2011) Munyaneza, Omar; Ndayisaba, C.; Wali, Umaru G.; Mulungu, Deogratias M. M.; Dulo, Simeon O.
Integrate Flood Management (IFM) integrates land and water resources development in a river basin, within the context of Integrated Water Resources Management (IWRM), with a view to maximizing the efficient use of flood plains and minimizing loss to life. For flood management to be carried out within the context of IWRM, Nile river basins should be considered as integrated systems. Socio-economic activities, land-use patterns, hydro-morphological processes, etc., need to be recognized as constituent parts of these systems. The aim of this paper is to identify the flood and drought periods in the river basin for future agricultural development and establish functioning integrated measures for flood and drought management in the Kagera Basin, which is one of sub-basin of Nile basin. Digital Elevation Model (DEM) map was used for Kagera river basin delimitation and its patterns (topography, land use and land cover). Impacts of floods and drought on livelihoods of residents were outlined. Survey methods were also used to derive a risk assessment methodology and management plans for hazard prone communities. The flood disaster management strategic plan in the Kagera Basin contains three phases such as prevention and mitigation before the occurrence, response in case of disaster, and rehabilitation after the occurrence. Thus, the most important key strategy is the cooperation and co-ordination across institutional boundaries, noting that the mandates of many institutions will either cover only part of the river basin or extend well beyond the basin boundary. At the core of integration is effective communication across institutional and disciplinary boundaries, which can take place only if there is a perception of common interest. Emphasis was on the adoption of flexible strategies tailored to each flood-prone region (characterized by their various physical, social, cultural and economic aspects) – recognizing the importance of evaluating different options and their relative advantages and disadvantages.
Long Term Hydrologic Modeling for Simiyu Watershed, Tanzania Using Hydrologic Simulation Program-Fortran (HSPF)
(2005-11-14) Salah, Ahmad M.; Mulungu, Deogratias M. M.; Mtalo, Felix W.
Simiyu watershed is one of the relatively mid-size river basins draining into Lake Victoria. The objective of this paper is to investigate the hydrologic response and to build a hydrologic model for the watershed. Hydrologic Simulation Program-Fortran (HSPF) and Watershed Modeling System (WMS) are used to build a long term model for the basin. WMS is used to analyze digital elevation and land use data as a pre-processor whereas HSPF is used to simulate daily stream flows. The initial model run indicated a need for calibration. Some model parameters are, thus manipulated to obtain a better fitting model. The calibrated model is, then, validated on a different data set. Statistical comparisons for calibrated and validated model showed no evidence of a great difference between the simulated and observed data. Hence, the model can be used for future runoff predictions in the basin. On the other hand, continuous enhancement efforts are required to improve the model predictive power.
Nyumba ya Mungu Reservoir System Simulation by Using HEC-ressim Model
(College of Engineering and Technology, University of Dar es Salaam, 2007) Mulungu, Deogratias M. M.; Ng'ondya, Rejea; Mtalo, Felix W.
This research paper focused on estimating effective water and optimization of the NyM reservoir for storage conservation and hydropower generation. Several models were used in the study: the Rainfall-Runoff model, GFFS was used to fill in missing data, and the HEC-ResSim Model and the NWBM for reservoir system simulation and water balance respectively. The effective inflows to the NyM reservoir were determined using HEC-ResSim model and the NWBM used to check the total water loss in the system. For the reservoir system simulation, the HEC-ResSim model was used to estimate water loss through irrigation abstractions in Kikuletwa and Ruvu reaches before water enters the NyM reservoir. The loss was estimated to be 27% of the total inflows at lDDl and lDCl gauging stations upstream the reservoir. Reservoir evaporation was estimated using pan evaporation data collected from NyM meteorological station. The effective inflows are important data to the reservoir system simulations for power production. The mean value of effective water reaching the NyM compared well with the previous study measurement of the d,y season value, which was done before the dam construction. The HEC-ResSim simulated releases were used to determine the power production at NyM hydropower plant. Considering water abstractions, the first simulated alternative favored storage conservation in the reservoir. The power achieved in this alternative was 7% above the TANESCO production (4/.6 GWh/yr). The second simulated alternative was to maximize power production at NyM hydropower plant. This alternative yielded 13% above TANESCO production. Despite the high energy attainable in maximization option, the reservoir water levels trend was seen to draw down drastically. The study also investigated the extent of the impact brought about by the abstracted water. If irrigation abstractions were restricted from the two reaches then power production would increase by 1/.5 GWh. This increment is about 24% above the power produced when abstraction is allowed in Ruvu and Kikuletwa River reaches.
A Physically Based Distributed Subsurface-Surface Flow Dynamics Model for Forested Mountainous Catchments
(Wiley, 2005) Mulungu, Deogratias M. M.; Ichikawa, Yutaka; Shiiba, Michiharu
This study was designed to develop a physically based hydrological model to describe the hydrological processes within forested mountainous river basins. The model describes the relationships between hydrological fluxes and catchment characteristics that are influenced by topography and land cover. Hydrological processes representative of temperate basins in steep terrain that are incorporated in the model include intercepted rainfall, evaporation, transpiration, infiltration into macropores, partitioning between preferential flow and soil matrix flow, percolation, capillary rise, surface flow (saturation-excess and return flow), subsurface flow (preferential subsurface flow and baseflow) and spatial water-table dynamics. The soil-vegetation-atmosphere transfer scheme used was the single-layer Penman-Monteith model, although a two-layer model was also provided. The catchment characteristics include topography (elevation, topographic indices), slope and contributing area, where a digital elevation model provided flow direction on the steepest gradient flow path. The hydrological fluxes and catchment characteristics are modelled based on the variable source-area concept, which defines the dynamics of the watershed response. Flow generated on land for each sub-basin is routed to the river channel by a kinematic wave model. In the river channel, the combined flows from sub-basins are routed by the Muskingum-Cunge model to the river outlet; these comprise inputs to the river downstream. The model was applied to the Hikimi river basin in Japan. Spatial decadal values of the normalized difference vegetation index and leaf area index were used for the yearly simulations. Results were satisfactory, as indicated by model efficiency criteria, and analysis showed that the rainfall input is not representative of the orographic lifting induced rainfall in the mountainous Hikimi river basin. Also, a simple representation of the effects of preferential flow within the soil matrix flow has a slight significance for soil moisture status, but is insignificant for river flow estimations
Resolving and Prevention of Shared Water Resources Conflicts
(2004-05) Mulungu, Deogratias M. M.; Mashauri, Damas A.
International shared water resources conflicts can be resolved through negotiation and arbitration. The negotiation and arbitration must be supplied with decision aiding tools and management plans for the shared water resources so as to come up with workable framework that can be used to prevent future water resources conflicts in the riparian countries. Various methodologies in literature have been given for conflict resolution with consideration to hydrological, environmental, economic, legal and political factors. Because of the complex nature of conflicts and cooperation, currently with the development of technology, computer and model applications are used to assist decision-making during conflicts and cooperation. In this paper, potential resolving and preventive alternative methods and/or experiences have been presented so that we can properly formulate and implement suitable policies, strategies and actions to avoid occurrence of water-based conflicts and their adverse consequences in Africa. As an example, conflicts and cooperation on some shared river basins in Africa (Nile river basin and SADC region rivers) have been highlighted. Learning from experiences from other parts of the world, it was recommended to incorporate game theory technique in water resources conflicts and cooperation in the African river basins for equitable and fair utilization and management of shared water.
Simiyu River Catchment Parameterization Using SWAT Model
(Elsevier, 2007) Mulungu, Deogratias M. M.; Munishi, Subira E.
The paper presents advances in hydrologic modelling of the Simiyu River catchment using the soil and water assessment tool (SWAT). In this study, the SWAT model set-up and subsequent application to the catchment was based on high-resolution data such as land use from 30m LandSat TM Satellite, 90m Digital Elevation Model and Soil from Soil and Terrain Database for Southern Africa (SOTERSAF).The land use data were reclassified based on some ground truth maps using IDRISI Kilimanjaro software. The Soil data were also reclassified manually to represent different soil hydrologic groups, which are important for the SWAT model set-up and simulations.The SWAT application first involved analysis of parameter sensitivity, which was then used for model auto-calibration that followed hierarchy of sensitive model parameters. The analysis of sensitive parameters and auto-calibration was achieved by sensitivity analysis and auto-calibration options, which are new in the recent version of SWAT, SWAT 2005.The paper discusses the results of sensitivity and auto-calibration analyses, and present optimum model parameters, which are important for operation and water/land management studies (e.g. rain-fed agriculture and erosion/sediment and pollutant transport) in the catchment using SWAT. The river discharge estimates from this and a previous study were compared so as to evaluate performances of the recent hydrologic simulations in the catchment.Results showed that surface water model parameters are the most sensitive and have more physical meaning especially CN2 (the most sensitive) and SOL_K. Simulation results showed more or less same estimate of river flow at Ndagalu gauging station. The model efficiencies (R2%) in this and in the pervious study during calibration and validation periods were, respectively, 13.73, 14.22 and 40.54, 36.17. The low level of model performance achieved in these studies showed that other factors than the spatial land data are greatly important for improvement of flow estimation by SWAT in Simiyu.

Browsing by Author "Mulungu, Deogratias M. M."

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