Department of Water Resources Engineering

Permanent URI for this collection

https://repository.udsm.ac.tz/handle/123456789/30

Browse

Recent Submissions

Now showing 1 - 20 of 116
  • No Thumbnail Available
    Item
    Pre-treatment of banana leaves with alkaline banana winery bottle-washing wastewater to improve the anaerobic digestion process
    (Springer, 2022-04-26) Edwin N.Richard, Edwin
    This study assessed the effectiveness of alkaline banana winery bottle-washing wastewater (ABW) as an alternative pre-treatment to improve hydrolysis rate and methane yield from banana leaves (BLs) wastes. The pre-treatment was carried out by soaking banana leaves in ABW for 48 h. The anaerobic digestion (AD) process was performed in batch reactors under the mesospheric temperature of 37 °C for 60 days. The pre-treatment results showed that the lignin concentrations in the pre-treated BL reduced by 4%, making it easier to digest. After the AD process, the hydrolysis rate (Kh) in the pre-treated BL was 0.02 d-1 higher than in the un-pre-treated BL (Kh = 0.003 d-1). The ABW pre-treatment significantly improved (P<0.05) the cumulative methane yield in BL. The pre-treated BL resulted in a high cumulative methane yield of 231 mL CH4 /g VS than un-pre-treated BL (46 mL CH4 /g VS). The volatile solids reduction in the pre-treated BL was 32.9% which was about 1.6 times higher than 20.8% in the un-pre-treated BL. Results indicated that alkaline pretreatment with banana winery bottle-washing wastewater could be an inexpensive alternative pre-treatment of BL and other lignocellulosic substrates before the AD process to improve biogas yield.
  • Thumbnail Image
    Item
    Occurrence of Arsenic in Groundwater, Soil and Sediments in Tanzania
    (CRC Press, 2016-06) Ligate, Fanuel; Ijumulana, Julian; Mtalo, Felix W.; Bhattacharya, Prosun; Bundschuh, Jochen
  • Thumbnail Image
    Item
    Developing innovations for adsorptive removal of arsenic from drinking water sources in North Mara gold mining area, Tanzania
    (Taylor & Francis, 2016-06) Irunde, Regina; Lesafi, F . J .; Mtalo, Felix W.; Bhattacharya, Prosun; Dutta, Joydeep; Bundschuh, Jochen
    Arsenic (As) contamination in drinking water have been reported to occur in areas where mining are practiced such as North Mara, lake Victoria basin in Mwanza, Geita and Rukwa. The removal of As requires methods such as ion-exchange, reverse osmosis, electrodialysis, contact precipitation, activated alumina, bone charcoal and activated clay. The use of ion-exchange, reverse osmosis and electrodialysis are expensive to be implemented in Tanzania. In order to safeguard the drinking water supplies, it is important to explore the low-cost and efficient locally available adsorbents such as activated alumina, bone char and clay for the removal of As for drinking water consumption.
  • Thumbnail Image
    Item
    Heavy Metals Inflow into Lake Muhazi, Rwanda
    (2012-01) Nhapi, Innocent; Wali, Umaru G.; Usanzineza, Denise; Banadda, Noble; Kashaigili, Japhet; Kimwaga, Richard; Gumindoga, Webster; Sendagi, S.
    Most tropical African lakes are facing pollution problems due to the rapid population growth and industrializa-tion in their riparian communities. Lake Muhazi in Rwanda is one of such lakes which has experienced a dramatic decrease in fish production since the eighties, with also reports of low water transparencies and high turbidities. The lakeshores are now being developed for ecotourism and this requires sound environmental management to make the planned activities viable. The purpose of this study was to assess heavy metal pollution in the tributary rivers of Lake Muhazi. The concentration of heavy metals in major tributaries was monitored for the period July to October 2007. The parameters studied are cadmium, chromium, copper, iron, lead, manganese, zinc, pH and temperature. Fourteen sampling stations on the Inflow Rivers and the spillway were monitored fortnightly. The samples collected for heavy metal analysis were preserved and stored in cooler boxes and analyzed in the laboratory using Standard Methods. Temperature and pH were measured in the field using HACH field testing kits. The concentration (mean ± standard deviation) of Zn was found to be 0.040±0.103 mg/L, Cd 0.031±0.007 mg/L, Pb 0.487±0.452 mg/L, Fe 7.53±13.34 mg/L, Mn 1.01±1.31 mg/L, chromium 0 mg/L and copper 0 mg/L. The concentrations of measured parameters deviate much from the recommended ones thus posing serious problems to aquatic life. It has also been shown that the high metal concentration levels in Lake Muhazi are related to landuse activities in the catchment. It is thus recommended that farming practices and erosion be controlled in the catchment to contain pollutant discharges into the lake. Lead is the main anthropogenic pollutant which has been found in the watershed of Lake Muhazi.
  • Thumbnail Image
    Item
    A review of modeling approaches in activated sludge systems
    (2011-07) Banadda, Noble; Nhapi, Innocent; Kimwaga, Richard
    The feasibility of using models to understand processes, predict and/or simulate, control, monitor and optimize WasteWater Treatment Plants (WWTPs) has been explored by a number of researchers. Mathematical modeling provides a powerful tool for design, operational assistance, forecast future behavior and control. A good model not only elucidates a better understanding of the complicated biological and chemical fundamentals but is also essential for process design, process start-up, dynamics predictions, process control and process optimization. This paper reviews developments and the application of different modeling approaches to wastewater treatment plants, especially activated sludge systems and processes therein in the last decade. In addition, we present an opinion on the wider wastewater treatment related research issues that need to be addressed through modeling.
  • Thumbnail Image
    Item
    Assessment of nutrient retention by Natete wetland Kampala, Uganda
    (2010-12) Kanyiginya, V.; Kansiime, Frank; Kimwaga, Richard; Mashauri, Damas A.
    Natete wetland which is located in a suburb of Kampala city in Uganda is dominated by Cyperus papyrus and covers an area of approximately 1km2. The wetland receives wastewater and runoff from Natete town which do not have a wastewater treatment facility. The main objective of this study was to assess nutrient retention of Natete wetland and specifically to: determine the wastewater flow patterns in the wetland; estimate the nutrient loads into and out of the wetland; determine the nutrient retention by soil, plants and water column in the wetland; and assess the above and belowground biomass density of the dominant vegetation. Soil, water and plant samples were taken at 50m intervals along two transects cut through the wetland; soil and water samples were taken at 10cm just below the surface. Physico-chemical parameters namely pH, electrical conductivity and temperature were measured in situ. Water samples were analyzed in the laboratory for ammonium-nitrogen, nitrate-nitrogen, total nitrogen, orthophosphate and total phosphorus. Electrical conductivity ranged between 113μS/cm and 530μS/cm and the wastewater flow was concentrated on the eastern side of the wetland. pH varied between 6 and 7, temperature ranged from 19°C to 24°C. NH4-N, NO3-N, and TN concentrations were retained by 21%, 98%, and 35% respectively. Phosphorus concentration was higher at the outlet of the wetland possibly due to release from sediments and leaching. Nutrient loads were higher at the inlet (12,614±394kgN/day and 778±159kgP/day) than the outlet (2368±425kgN/day and 216±56kgP/day) indicating retention by the wetland. Plants stored most nutrients compared to soil and water. The belowground biomass of papyrus vegetation in the wetland was higher (1288.4±8.3gDW/m2) than the aboveground biomass (1019.7±13.8gDW/m2). Plant uptake is one of the important routes of nutrient retention in Natete wetland. It is recommended that harvesting papyrus can be an effective way of nutrient removal especially phosphorus which is not easily lost to the atmosphere like nitrogen. Natete wetland needs to be left in its natural state for better efficiency in nutrient retention. Bio-manipulation of the wetland by spreading the wastewater as it enters the wetland could enhance the interaction between plants and wastewater and subsequent nutrient removal.
  • Thumbnail Image
    Item
    Characterization of wastewater from an Abattoir in Rwanda and the impact on downstream water quality
    (2010-01) Muhirwa, Déogratias; Nhapi, Innocent; Wali, Umaru G.; Banadda, Noble; Kashaigili, Japhet; Kimwaga, Richard
    This study analyzed processes and products at Nyabugogo Abattoir in Kigali, Rwanda, and investigated how they can be optimized for environmental safety. The average capacity of the abattoir is 566 cattle and 1,512 goats and sheep slaughtered per week. The study assessed the quantity and quality of different raw materials, by-products and wastewater streams and the potential impacts of applying cleaner production principles in abattoir processes. The samples were collected fortnightly, and analyzed using Standard Methods. The analysis emphasized on nutrients, biologically active constituents, and receiving water impacts. The data were processed for trends and variance using SPSS computer package. The wastewater parameters analyzed are temperature, salinity, conductivity, turbidity, dissolved oxygen pH, TSS, TDS, BOD5, COD, fat oils and grease, NO3-N, TKN, total phosphorus, chloride, calcium and total coliforms. The findings showed that the abattoir wastewater streams' total chemical oxygen demand (TCOD) ranged from (7,533±723) for evisceration to (23,778±1,673) mgl-1 from slaughtering step and the discharge into Mpazi River increased its TCOD from (213±29) to (852±94) mgl-1. The TSS varied between 2,452±51 from the slaughter process and 5,252±174 mgl-1 for the effluent from the goat and sheep slaughter section. Results from the bacteriological analysis showed that the average abattoir wastewater discharge count was (560±81)105 cfu/100ml of total coliforms which increased from (2.8±0.58)105 to (8.2±0.86)105 cfu/100 ml. It was concluded that the current effluent quality is not suitable for discharge into watercourses. It was recommended that further treatment of the effluent is required coupled with the application of cleaner production principles.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    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
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    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
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    Integrated Model for Estimating Sediment Discharge to Coastal Environment from River Basin
    (2006-01) Norbert, Joel; Shibayama, Tomoya
    In this study an integrated model to estimate total sediment discharge from the river basin to the coastal environment is developed. Simulated and measured sediments discharge at the river mouth is compared and there is a good agreement. Also the effect of land use and climate change to the sediment yield is analyzed. The land use data derived from remotely sensed images of 1976 and 1997 is used as the basis for comparison to see the effect of land use change. It was observed that using the land use data for the year 1997, total sediment discharge to the coastal environment increased as compared to the year 1976; this is mainly due to the increased agricultural areas and residential areas and also decreases in forest area. For analyzing the effect of climate change, HadCM2 model is used to generate mean daily precipitation for the month for the period 2040-2050 and then daily rainfall amount is generated from this data using exponential distribution. The results of the sediments discharge to the coastal environment using this generated data show a decrease in the average annual sediment discharge.
  • Thumbnail Image
    Item
    Meeting the Water and Sanitation MDGs: A Study of Human Resource Development Requirements in Tanzania
    (2013-10) Kimwaga, Richard; Norbert, Joel; Kongo, Victor; Ngwisa, Mpembe
    In the Tanzanian water and sanitation (WatSan) sector, the human resource (HR) requirements for meeting the Millennium Development Goal (MDG) targets have so far been relatively unknown. This study was therefore conducted with a focus on determining HR requirements in the public sector and parastatal institutions, in the private sector (private consultancy companies, individual contractors, etc.), and in non-governmental organizations and community-based organizations active in the broader water, sanitation and hygiene (WASH) sector. The competences assessed were: design and construction of new infrastructure, operation and maintenance (O&M), community mobilization, sanitation, and hygiene promotion. The study found a greater HR shortage in rural areas than in urban areas. The smallest HR need is for social development professionals (estimated at 320 in the urban areas). In the water supply and sanitation sectors, the average number of water supply engineers that will be required to achieve MDGs is estimated at 3,864, compared to the sanitation sector, which will need 637 engineers. In terms of the demand for competences in the water supply sector, the highest need is for O&M professionals (7,589) and the lowest for mobilization professionals (447). The study recommends increasing the HR supply in the WatSan sector through the following measures: increasing support for training institutions offering relevant courses in WatSan; focusing on skills required for asset management and O&M; and giving specific attention to HR capacity development in small towns and rural areas.
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    Estimation of Design Floods in Un-gauged Catchments using a Regional Index Flood Method. A Case Study of Lake Victoria Basin in Kenya
    (Elsevier, 2014) Norbert, Joel; Mugo, Margaret; Gadain, Hussein
    Reliable estimation of flood magnitudes corresponding to required return periods, vital for structural design purposes, is impacted by lack of hydrological data in the study area of Lake Victoria Basin in Kenya. Use of regional information, derived from data at gauged sites and regionalized for use at any location within a homogenous region, would improve the reliability of the design flood estimation. Therefore, the regional index flood method has been applied. Based on data from 14 gauged sites, a delineation of the basin into two homogenous regions was achieved using elevation variation (90-m DEM), spatial annual rainfall pattern and Principal Component Analysis of seasonal rainfall patterns (from 94 rainfall stations). At site annual maximum series were modelled using the Log normal (LN) (3P), Log Logistic Distribution (LLG), Generalized Extreme Value (GEV) and Log Pearson Type 3 (LP3) distributions. The parameters of the distributions were estimated using the method of probability weighted moments. Goodness of fit tests were applied and the GEV was identified as the most appropriate model for each site. Based on the GEV model, flood quantiles were estimated and regional frequency curves derived from the averaged at site growth curves. Using the least squares regression method, relationships were developed between the index flood, which is defined as the Mean Annual Flood (MAF) and catchment characteristics. The relationships indicated area, mean annual rainfall and altitude were the three significant variables that greatly influence the index flood. Thereafter, estimates of flood magnitudes in ungauged catchments within a homogenous region were estimated from the derived equations for index flood and quantiles from the regional curves. These estimates will improve flood risk estimation and to support water management and engineering decisions and actions.