Water Supply and Environmental Engineering

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    Alternate Solution to Lake Beseka Water Level Rise Containment
    (Addis Ababa University, 2017-06) Lulit, Habte; Mebruk, Mohammed (PhD)
    Environmental change that has taken place over the last few decades is an essential task to understand the impacts that natural processes and anthropogenic factors have on hydrological settings and ecosystems. Environmental concern regarding the expansion of Lake Beseka has become a major issue. The expansion of Lake Beseka has caused an irreversible damage to the nearby Awash River which is a resource for the surrounding irrigation schemes and downstream water supply. This paper tried to predict the maximum possible Lake level so that it is contained in its territory to control the contamination of Awash River. A numerical groundwater model, TAGSAC, has been used for predicting this maximum possible Lake level rise. For the identification, a steady state groundwater model was first created and calibrated for the inventoried wells. The model is conceptualized by considering a constant head boundary condition for the Awash River in locations where the river is perennial. The calibration of the model was made by changing the recharge and hydrogeologic parameters of the basins. The goodness of fit indicators (GoFIs) showed that the measured and simulated heads of the model have a better match. The maximum Lake level rise was determined by raising the lake water level where the flow was reversed away from the Lake by assuming the Lake is contained in its territory. As the result of this study indicates the maximum Lake level where the flow completely reversed is 12m.
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    Application of Genetic algorithm and Artificial Neural Network in Water Consumption Forecasting and Driving Factors Determination
    (Addis Ababa University, 2024) Terefe Tilahun; Mebruk Mohammed (PhD)
    Accurate understanding of water consumption is paramount for effective resource management, infrastructure planning, and ensuring a reliable water supply. Understanding and determining the driving factors of water consumption has become a key challenge. In order to address this issue, the study employs Genetic Algorithm (adopted for both linear and nonlinear regression) along with an ANN model consisting of one hidden layer with either one or five nodes. The GA and ANN models were used to predict water consumption in Addis Ababa city and analyze the driving factors behind water consumption. The model was developed using input data such as water consumption time series, average temperature, population, construction activity, relative humidity, economic development, number of livestock, industrial development, and holiday/festival. Monthly data on water consumption and meteorology (from 2015 (June) to 2023(August)) were gathered from Addis Ababa city water and sewerage authority, as well as the National Meteorological Agency. Sensitivity analysis is used in the forecasting process to choose the most important explanatory factors. Four different models were developed and their performances were assessed using two metrics: root mean squared error (RMSE) and Normalized root mean squared error (NRMSE). The linear regression GA model achieved an RMSE value of 0.355 Mm3/month and an NRMSE value of 0.0451. On the other hand, the nonlinear regression GA model yielded an RMSE value of 0.339 Mm3/month and an NRMSE value of 0.0430. Moving on to the ANN model with one hidden node, it achieved an RMSE value of 0.325 Mm3/month and an NRMSE value of 0.0413. Lastly, the ANN model with five hidden nodes achieved the lowest RMSE value of 0.3195 Mm3/month and the lowest NRMSE value of 0.0405. Among the four models, the ANN model with five hidden nodes performed the best, according to these results. The study conducted using ANN model with five hidden nodes revealed that the primary factors influencing water consumption in Addis Ababa city are population, relative humidity, and industrial activity. Population was identified as the most significant factors, with an effect size of 18.73%, followed by relative humidity at 16.65% and industrial activity at 12.77%. The additional factors play a substantial role (ranging from 1.1% for average temperature to 11.3% for livestock), to the point that neglecting them in water consumption calculations could result in inaccuracies when forecasting future demand trends.It is recommended that future predictions of water consumption in Addis Ababa city take into account nine driving factors: population, average temperature, construction activity, relative humidity, economic development, agricultural activity, industrial development, holiday/festival, and precipitation.
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    The Application of High Rate Tube Settler - The Case of Legadadi Water Supply Treatment Plant
    (Addis Ababa University, 2015-06) Obsa, Bayissa; Esayas, Gebreyouhannes (PhD)
    In modern water supply treatment plant high rate settler units achieve effective settling process than conventional sedimentation tank. This high rate settler can be considered during the new sedimentation tank construction and also existing sedimentation tanks can be modified by including such units. This study was aimed at the assessment and evaluation of the application of high rate tube settlers in the case of Legadadi Water Supply Treatment plant by two main methods. The first one is by comparing and evaluating the performance of settling process of the sedimentation tank that the high rate tube settler is provided for it and the one without it. The second method contained the pilot scale experiment developed at this treatment plant to evaluate and asses the performance of the existing one. The comparatives and experimental results concluded optimistically that the high rate tube settler can provide better performance than that of the conventional sedimentation tanks. The comparative results indicates that the performance in production efficiency increase by 34.5% and the effects of HRTS on filtration units saves 35.11% water use for filter back washing. Additionally the pilot experimental result due to high rate tube settlers’ shows that the production efficiency increased by 35.30%, detention time decreased by 33.7%, turbidity reduction is increased by 76.65% and the chemical amount required is reduced significantly. Therefore; from the results of the two study it is possible to conclude that the application of high rate tube settlers provides effective sedimentation process ,positive effect on filtration unit, and cost effective in(structural and land cost of sedimentation tank, chemical cost and other operational costs). The results of the study offered to recommend that the Legadadi Water Supply treatment can upgrade and improve the efficiency of process relative to the pilot scale results and; Other Water Supply institutions have to use this high rate tube settler to gain all important advantageous to be achieved.
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    Artificial Neural Network and Fuzzy Logic for Water Demand forecasting (In case of Mekelle city)
    (Addis Ababa University, 2018-05) Gebrewahid, Adhana; Mebrate, Taffese (PhD)
    The methodology emphasizes the importance of the new predictive model development, and to account for water demand uncertainty, through evaluation of the reliability of model predictive. In this thesis Artificial Neural Networks (ANN) and fuzzy logic models were used for Mekelle city water consumption predictions analysis. Water consumption data collected from Mekelle city water and sewerage authority and independent monthly climate data were obtained from the National Metrological Agency. Sensitivity analysis was applied to selection most relevant minimum explanatory variables in the forecasting process. These data were used in both ANN and the fuzzy model setting up, testing and validation. To build ANN model the available dataset were divided into 3 subsets: 70% of the data for model development; (15%) of the data are used for training; and (15%) of the data are used validation to determine the optimal number of inputs and optimal number of hidden neurons. Both input variables and the output variable of the water consumption were fuzzified and triangular fuzzy membership functions were created. The Mamdani fuzzy rules in If–Then format with the centroid defuzzification method were employed. Seven ANN model were developed with different weather combination as input variable and Model one were found best with a root mean square error (RMSE) of 30.96, mean absolute percentage error (MAPE) 2.54, correlation coefficient (R2) of 0.98 and 97.46% of forecasting accuracy. The average absolute percentage error of the fuzzy model was found as 19.2%. Therefore, in this research ANN model is successfully presented for predicting water consumption in Mekelle city with climate inputs, cost of water and population compared with the fuzzy prediction system.
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    Assessment of Cactus Biosorption Potential in The Removal of Hexachromium Ions from Synthetic and Tannery Waste Water
    (Addis Ababa University, 2018-06) Getahun, Mebrate; Geremew, Sahilu (PhD)
    Chromium (VI) is environmentally mobile owing to its high solubility in water. Its pollution is largely attributed by discharge of inadequately treated effluents of chrome utilizing industries. Discharges of such effluents pose a potential threat to human health unless are treated properly before its disposal. Adsorption using activated carbon prepared from biomaterials is a new technology for the treatment of heavy metals rich industrial effluents. Opuntia Ficus Indicus (OFI) activated with H3PO4 (45%) was evaluated for Cr (VI) removal capability from both synthetic and tannery waste water. The present work was aimed at assessing the biosorbent capability of OFI in removal of Cr (VI) from synthetic aqueous solution and tannery waste water. OFI was activated with H3PO4 (45%) and carbonized at 450 o C in muffle furnace for 1hr and its different physical properties such as bulk density and moisture content was determined. Besides; the sorbent characterized by FTIR spectroscopy test analysis before and after adsorption processes, suggested possible key contributions of hydroxyls and carboxyls in the sequestering of Cr(VI) on OFI. Maximum Cr(VI) removal efficiency of 99.5% was achieved by OFI under different study parameters. The percentage removal of Cr (VI) ions increased with increase of the amount of sorbent concentration for which the Optimum removal of Cr (VI) was observed at sorbent dose of 125 mg. The adsorption efficiency of Cr (VI) on OFI was increased at low pH values between 2 and 3, attending its optimum at pH of 2. Percentage removal was observed to increase, while decreasing the initial concentration of Cr (VI) to which 6mg/l was the minimum of adsorption system. Whereas; the removal was increased with increasing the agitating speed and its corresponding contact time, whereby; the optimal adsorption reached at 60 minutes at 150rpm agitating speed. Both Langmuir and Freundlich models and followed adsorption process with high regression correlation coefficient (R 2 ) values of 0.999 and 0.956 respectively. But, Langmuir isotherm with higher R 2 was best fitted to the experimental values, with monolayer adsorption capacity of 4.587mg/l. Besides; the RL values were obtained in range of 0 < RL < 1 that confirmed the favorability of adsorption process. The optimized parameters were applied to the real waste water resulted in 88.7% of optimal adsorption removal efficiency. The reduction in percentage of removal might be due the matrix effect of the competing ions present the chrome liquor spent. Adsorbent used in present study was prepared at laboratory scale and observed to hold distinct position for its efficient removal of Cr (VI) both from synthetic aqueous solution and tannery waste water and could be an alternative promising plant based biosorbent in field.
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    Assessment of Emdibir Town Water Supply System in Cheha Woreda, Gurage Zone, SNNPR, Ethiopia
    (Addis Ababa University, 2019) Antonyos, Wodajo; Geremew, Sahilu (PhD)
    Urban water supply and consumption challenges are the widespread problems in most of the developing countries such as Ethiopia. The thesis paper focused on the water supply system of Emdibir town, capital city of Cheha Woreda Guraghe zone of Southern Nation Nationality People Regional State of Ethiopia. The main objective of this study was to assess the water supply systems of Emdibir town and to suggest some remedial measure. The water supply coverage has been evaluated by depending on the amount of water production and consumption rate. The existing water distribution system was analyzed by using Water GEMS software. The model can be used to identify the zone of high pressure and low pressure in junctions and the level of velocity through pipe. In addition, sample pressure filed data used to compare with the computed value. The analysis result has confirmed that the current water supply coverage of the town is 63.3 % of maximum daily demand. The current average per capita water production is 24.71/c/day. From one year production and consumption data the average loss become 21.4%. There are aged pipes, oversized and undersized pipes, high pressures and low pressure, high gap between demand and supply, pump capacity problem in the system. The study concluded that the total water demand and the current level of water supply service in the town are not adequate. Therefore, taking these challenges into consideration, it was suggested that providing alternative water sources, active involvement of the communities and participation of different actors and other sustainable approaches would prove to be an effective and efficient adaptive measures.
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    Assessment of Ethiopian Plumbing Code and its Compliance for High-rise Buildings in Addis Ababa, Ethiopia
    (Addis Ababa University, 2024-10) Teshager Gebeyehu; Agzew Nigussie (PhD)
    The thesis examines the compliance of Ethiopian plumbing code for high rise buildings in Addis Ababa city. The adequacy of Ethiopian plumbing code with other international plumbing codes and its effectiveness of the design and installations of water supply systems of a building, the design and installation of internal waste water drainage systems of a building, the design and installation of external waste water drainage systems of a building (septic tank), the code compliance of installed sanitary fixtures and appliances and the design and installation of roof storm water drainage systems using both the international and local plumbing codes. New technology PEX-AL-PEX pipe material, grease interceptor for kitchen sink and vent piping system were used for over viewing of Ethiopian plumping codes to the other international plumbing code. Hazzen William equation, plumber’s chart, flow rate and loading units of fixture units were used the analysis of the design of water supply system. The traps and loading units of sanitary appliance, slope and horizontal pipe size, fixture units and vertical pipe size of stack, total loading unit of fixtures and pipe size for both common and combined vent were used the analysis of internal wastewater drainage systems of a building. The rate of flow method, discharge versus total loading unit chart, standard area covered for storage septic tank, volume of sediment, volume of sludge were used the analysis of external waste water drainage systems of a building. Discharge of roof storm water by rational formula. Pipe size capacity of down pipe, intensity of rain fall and specifications of roof gutter were used the analysis of roof storm water drainage system of a building. The local Ethiopian plumbing code was used for analysis of internal waste water drainage systems and the roof storm - water drainage. The international plumbing code and Indian plumbing code is good for analysis of water supply pipe lines and external waste water drainage system. The study focused on assessing whether the installed plumbing components of selected buildings meets the established design requirements, standards and regulations of plumbing codes. Recommendations were also provided to ensure optimal plumbing system designs, functionality and compliance with relevant plumbing codes and standard requirements.
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    Assessment of Impacts of Urbanization on Surface Water Quality, The Case of Keha River, Gondar Town
    (Addis Ababa University, 2018-10) Amsalu, Alemu; Geremew, Sahilu (PhD)
    This study assessed the impacts of urbanization on surface water quality and identify the sources of pollution on Keha River in Gondar town. Urbanization and anthropogenic activities are the key factor causing water quality degradation as we go downstream along Keha River. Based on Keha watershed land use land cover in1999,2004,2006 and 2017, it is shown that there is significant land use change of the bare land, grassland and agricultural land converted into urban land use and Keha River water quality has deteriorate in the past 15 years. The critical source of pollutions are industries like Moha soft drink industry, Gondar hospital, Kedame Gebeya Commercial market, a lot of hotels and restaurants among others. To analyze the river water quality fourteen (14) different strategic sampling sites were selected. The analysis consisted of in situ and laboratory analysis of samples using standard methods. The result indicated that the range of PH (5.9-8.97mg/l), Conductivity (142-1231 us/cm), Turbidity (8-1072 NTU), Dissolved Oxygen (7.4-2.1mg/l), BOD (4.1-217mg/l), TDS (102-1298mg/l), Alkalinity (89-508mg/l), Total Hardness(103283mg/l), Iron(0.15-0.76), Chromium(0.02-0.42), Manganese(0.02-3.9), Phosphate(1.3732.7mg/l), Nitrate(35.4-178mg/l), Total coliform counts(2.9-495) and E.Coli counts (2273.8) for rainy and dry seasons. At all sampling sites except upstream of Keha River the Physico- chemical and bacteriological results of water samples were above the Ethiopian and WHO standard limit indicated that Keha River was polluted. Except upstream of Keha River, at all sites the Dissolved Oxygen (DO) is less than 5 mg/l that is below the WHO and Ethiopian minimum standard limit. High nitrate and phosphate cause of eutrophication, high total coliform and high E.coli lead to water borne disease and the death of the communities especially children because some people like the daily laborers and street children were used for drinking this polluted River within the study area. It is therefore concluded that the river in the study area is polluted and not fit for domestic use. It is recommended that the water of Keha River should not be used directly for domestic purposes. It is also recommended that an IWRM approach be used in order to solve the pollution problem. Keha River health restorative work is require for multiple importance such as ecosystem regeneration, water quality improvements, reduce any negative impacts on the water resources and aquatic life of Keha River.
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    Assessment of Lead Contamination via Soil and Water in Addis Ababa Daycares
    (Addis Ababa University, 2023-04) Eden Belete; Zerihun Getaneh (PhD)
    Lead exposure can come from different environmental media soil, water and air impose negative health effects if ingested by humans, children’s are the most vulnerable. The objective of the study were to investigate i) lead level in water and soil of daycares facilities in Addis Ababa, ii) lead level in water sources (both surfaces and ground water) that supply water sources to Addis Ababa city. Graphite Furnaces Atomic Absorption Spectroscopy were used to analyze the concentration of lead in soil and tap water of 28 day cares. Samples were taken from 11 sub cities, sample size were determined based on the number of daycares in each sub city. Sample from sources (ground and surfaces) of water supply were also analyzed. The result indicated that the mean level of lead in soil and water of day cares were 2.37 and 8.26μg/l are within the permissible value of 10μg/L according to WHO standard. The result from sources of water shows that the lead level in surfaces water sources before treatment were above the permissible value (10μg/L ) whereas the ground water sources were within in the acceptable limits . Integrated exposure uptake bio-kinetic model were used to determine the blood lead level of children’s below 4 year of age. The mean blood lead level were 1.78μg/dl. Even if the BLL were below the blood reference value of 3.5μg/dl (according to CDC) there is no safe blood lead level value low lead level can have adverse effects in children. Lead level in drinking water from daycare centers is greater than the lead concentration from water sources this shows that there is sources of lead in between water sources and daycare tap water.
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    Assessment of Lead Exposure and Microbial Contamination in Addis Ababa Kindergarten Schools’ Tap Water
    (Addis Ababa University, 2018-10) Dawit, Debebe; Fiseha, Behulu (PhD)
    The objective of this study is to evaluate the quality of water consumed by kindergarten school children in Addis Ababa city, who are highly susceptible to issues associated with heavy metal in water. Through conducting chemical analysis, the level of Lead (Pb) using Micro Plasma Atomic Emission Spectrophotometer (MP-AES), total coliforms & E.coli in the water distribution system were measured at 38 schools. The study can be considered as an unprecedented piece of work as it addresses critical issues and methods to mitigate the problems caused by high concentration of Pb in water supply distribution infrastructure. The samples were taken from 3 water supply sub-systems; Akaki, Legedadi and Gefersa. The results revealed that the average Pb concentration in the city was 62.37μg/L which was higher than the WHO recommended threshold value of 10μg/L. The children’s blood lead levels and exposure to Pb was also calculated using integrated exposure uptake bio-kinetic (IEUBK) model as per the USEPA guidelines. In average figure, the model predicted that 20.17% of the children in the city will have their blood lead levels above the WHO recommended 10μg/dL. In the microbial analysis, 7 out of 38 schools were contaminated with total coliform bacteria. However, E. coli was not detected in any of the samples, meaning that all samples were free from fecal contamination. In addition, the free chlorine level of the samples was also tested. The results indicated that 16 out of 38 (42.1%) of the water samples had a free chlorine value below the WHO recommended 0.2mg/L. It is therefore, possible to conclude that regardless of the different water sources, a water supply infrastructure determines the concentration levels of lead and residual chlorine that reaches the end users.
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    Assessment of Non-Revenue Water and Infrastructure Leakage Index (Ili) Applicability: A Comparative Study In Ethiopian Towns - Adama, Bishoftu, And Mojo
    (Addis Ababa University, 2024-02) Zelalem Tamyalew; Geremew Sahilu (PhD)
    Water utilities in Adama, Bishoftu, and Mojo towns are experiencing significant water losses in their supply systems. To improve their efficiency, utilities need to be able to measure and assess the performance of their water supply systems. One frequently used performance indicator (PI) is the Infrastructure Leakage Index (ILI). However, the applicability of ILI performance indicators in the water utilities of these towns depends on their current conditions. This study aims to check the suitability of using the Infrastructure Leakage Index (ILI) in Adama, Bishoftu, and Mojo towns in Ethiopia. The primary and secondary data were collected to analyze the water balance and evaluate ILI. Secondary data included system input volume, authorized consumption, and unauthorized consumption, while primary data included water meter inaccuracies, customer water meter inventory, and measurement of pressure in the water supply system for the calibration of Water Gems Connect Edition update 2. The analysis revealed that the non-revenue water (NRW) is high, reaching up to 32.6%, 38.33%, and 47.33%, respectively, as a percentage of system input volume. Additionally, the total water loss for Adama, Bishoftu, and Mojo is 32%, 37.3%, and 45%, respectively, as percentage of system input volume. Of the total water loss in each town, 80.8%, 81%, and 88.33% are real losses, while the remainder is apparent losses. The study also indicates that the ILI result of the town water supply system is excellent, with values of 3.7, 4.4, and 3.3 for Adama, Bishoftu, and Mojo, respectively. However, this result contrasts with the current water loss and NRW, indicating that the ILI does not fully capture the specific challenges faced by Ethiopian towns, such as poor asset management and supply intermittency. Therefore, it is necessary to check the applicability of using ILI in Ethiopia before using it as a system performance indicator.
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    Assessment of Pipe Failure Causes (Case Study on Chiro Town Water Supply Distribution System), Ethiopia
    (Addis Ababa University, 2021-09) Masho, Dekamo; Geremew, Sahilu (PhD)
    Intermittent water distribution is the key problem of many water authorities in developing countries including Ethiopia. Hence, this research was conducted to carry out a risk assessment of water supply pipe failure (burst) in the water supply system of Chiro town which is located in the eastern Oromia Region of Ethiopia. To investigate the cause of pipe burst in the town water supply distribution network, physical, pipe installation condition investigations of the distribution system and water GEMS modeling were utilized. Chiro town water supply distribution system was constructed in 2013 to 2015. More pipes were laid from 2014 to 2015 especially uPVC pipe and HDPE, but more pipe bursts were observed in uPVC pipe and HDPE pipe. According to pipe failure (burst) history recorded in the town water supply distribution system, more types of pipe burst were found in plastic pipe (uPVC pipe and HDPE) than the other types of pipe (DCI and GI pipes). The water supply distribution piping is mainly of plastic pipes (89.17%) and 10.83 % other types. According to Chiro town’s water distribution system, the investigation of the factors causing pipe failure in the system was based on considering three factors (pipe condition assessment) such as physical factors (types of pipe materials, pipe diameter, pipe installation years), environmental factors or pipe installation conditions (pipe cover, pipe bedding and backfill practiced conditions) and hydraulic parameters (internal water pressure, transient pressure and also velocity). As per the research results, the main causes of pipe burst in the water supply system were the type of pipe materials and its PN, water pressure, poor pipe installation practices, absence of selected material pipe bedding specially at rocky area and also absence of sufficient pipe cover and back fill for plastic pipe or uPVC and HDPE pipes. In general, frequent pipe burst in the system leads to water losses and this contributes to interruptions (intermittent) of water supply in the town. Based on pipe condition/situation assessment and the relation between the parameters which contributes to pipe failure, identify which parameter/s are more related to the cases of pipe failure than the others and develop equation based on their relationship of the parameters with the probability of pipe failures. This is significant to rehabilitate /replacement/repair and improve the reliability of town water distribution system and providing more attention to pipe burst reduction strategies which are vital for remedial measures.
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    Assessment of reasons for Yield Decrease of Water Wells in Akaki Well Field based of Design, Construction and Operation
    (Addis Ababa University, 2022-03) Bethelhem, Kena; Mebruk, Mohammed (PhD)
    Groundwater is of paramount importance for the city of Addis Ababa and the majority of the groundwater supplied to the city comes from drilled wells in and around Akaki-Kality sub city. Even though numerous water wells are built over the years, the majority of the wells fell to provide anticipated design yield. The study mapped 70 wells found in Akaki Phase I, Akaki Phase II, Akaki Phase IIIA & Akaki Phase IIIB on ARCMAP to see the spatial distribution of wells and their performance over the years. From the map, some wells were observed to perform better than their neighboring wells and some wells were found to perform worse than the neighboring wells. Therefore the research engrossed in understanding the reason behind this phenomenon mainly by focusing on the design, construction, and operation of selected wells from all phases of Akaki well field. The selected 35 wells were grouped in accordance with their performance. Data from the well-completion report was organized and analyzed to identify the possible reason for the decrease in yield. Parameters used to compare the grouped wells were depth, elevation, screen arrangement, geologic medium, filter material used, construction process, year of construction, and the drilling contractor. The result showed bottom elevation of some better performing wells is deeper than those in a worse condition which means they are tapping water from a deeper aquifer. Another finding was 60% of the study wells have 30-50% of their casing screened. Some wells perform worse than their surrounding wells because their screened section is lower. For these wells, it can be suggested to increase the screen section in accordance with the water-bearing formation. From the analysis done using the Cooper Jacob method, it was found that the majority of the wells are developed within the radius of influence of one another meaning pumping water from one well is affecting the neighboring wells. Another finding of the research is the drawdown result from single and multiple well tests which showed 100% of the wells are being affected by the surrounding wells which supports the result obtained on the radius of influence of those same wells.
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    Assessment of Solid Waste Collection Capacity in Addis Ababa, Ethiopia
    (Addis Ababa University, 2019-06) Solyana, Aweke; Alemtsehay, Gebremeskel (PhD)
    Waste collection and transportation is one of the crucial functional elements of municipal solid waste management. Available information about this matter is therefore essential for successful municipal solid waste management. The main objective of this study is to assess the solid waste collection practice in Addis Ababa. For the purpose of the study, 250 pre collector groups were selected for field survey of the primary solid waste collection. Background information was gathered using semi structured interviews with the pre collector groups and the respective cleansing management agency officers. To examine the secondary solid waste collection, field observation on the trucks and interviews with truck drivers and with waste agency officers of the city was carried out. From the study, the productivity of primary and secondary waste collection was determined; the collection capacity of the city was estimated and factors influencing the system were identified. For primary collection, three different collection methods were identified: push cart method, pushcart–collector method and truck collection method with average productivity of 2.12 m 3 /hr respectively. For secondary waste collection, the trucks productivity were determined to be 6.29 m / worker/day and 2.81m 3 / worker/day and 4.2m 3 /hr for container truck, 18.29 m 3 3 /hr for compactor (40 m 3 3 ) and 39.7 m /hr for compactor (80 m 3 ). The solid waste collection capacity was determined to be 3,192,868.8 m /year for the primary collection and 2,579,183.22 m 3 /year for the secondary collection. The solid waste generation rate of the city is determined to be 4, 157469.12m3/year. This shows that, on average, only 76% of the waste generated in the city was collected by primary collectors, and 80% was collected by the secondary collectors. The result indicates that the current collection system doesn’t cope with the solid waste generation rate of the city. 3 The role of solid waste transfer station in solid waste management is great. This study includes the basis of design and conceptual layout for a new facility of a pilot service area. This design and operational plan details the features and operational procedures for a municipal solid waste transfer station to ensure a safe, operationally efficient facility that meets the waste needs of the given service area.
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    Assessment of Storm Water Drainage System Performance of Mojo Town, Central Ethiopia
    (Addis Ababa University, 2020-12) Mezmur, Hawaz; Geremew, Sahilu (PhD)
    The main objective of this study was to assess the existing storm water drainage performance of Mojo town and to provide the possible recommendations or engineering measures that enables to alleviate the prevailing problems. Storm Water Management Model (SWMM), which is a dynamic rainfall runoff simulation model widely applied for urban drainage, was chosen for the performance evaluation to assess the triggering factors as well. The model was developed based on a selected area of 354 ha, that has been a flood prone area mainly due to the construction of two mega projects. The model area is divided in to 45 sub catchments with a drainage network of 94 conduits, 74 junctions and 2 outfalls. Three important inputs for the model were organized: Rainfall, infiltration and physical characteristic of the model area. 1. Rainfall depths of twenty-one years (1997-2017) of Mojo metrology station were obtained from National Metrological Agency. An IDF curve for different return periods (2,5,10,25,50,100yrs) formulated by Log person type III distribution method was used as an input for the model due to its slightly better coefficient of determination than Gumbel method.2. Infiltration of the model area is represented by Green-Ampt equation.3 Physical characteristics of the sub catchments including topography of the model area was analyzed using Global mapper, ArcGIS software. Besides, three successive Google earth images were used to analyze the land use land cover change of the model area through 11 years (2009-2019) period. Based on the inputs the model is built and model parameters were derived based on characteristics of the sub catchments and drains infrastructures. According to the sensitivity analysis, catchment width and Manning roughness coefficient for pervious areas were found the most sensitive parameters. Three drains (D_48, D_89 & D_90) were selected for calibration and validation. Three rainfall event observations for calibration and one event for validation were used on the two most sensitive parameters until the simulated and observed values reached at acceptable level. The performance of SWWM is insured based on an evaluation that is made by coefficient of determination (R2) and Nash-Sutcliffe Efficiency Coefficient (NSE). The model is simulated for one rainfall event, for different return periods and 3 hours rainfall duration. According to 10 years return period of simulation regarding storm water discharge, 25 conduits and 28 junctions were flooded which is 27.0 % and 37.8% respectively. An increment in terms of Peak runoff, total runoff & peak discharge is observed due to LULC change. The other important issue is a significant proportion of the drainage system is subjected to below 0.9m3/s flow velocity that insists deposition of solid material in drains which affects the system performance. Among the various low impact development (LID) structural measures, Bio retention and Infiltration trench are incorporated and simulated in the model. Based on 10 yrs & 25 yrs return period simulation for LID, improvements in terms of peak discharges decrease and elongated peak time discharge were observed where LID is applied. Regarding 10 yrs period ,the magnitude of peak discharge of drains is decreased with the minimum of 1.5% and maximum of 35.1.Generally, the drainage system of the town is not suffice for the runoff generated from the town because of intensive land use/land cover (LULC) change as well as lack of green areas in required proportion. The major source of overflow of drains is highly related to the construction of the two mega projects. Minimum flow velocity, which is below cleansing velocity, is the other problem that affects the drainage system performance. In terms of quality, different studies verified that storm water of Mojo town is highly polluted due to mainly industrial pollution. This study mainly recommends proper implementation of the town master plan in such a way to regulate reasonable land use land cover. Redesigning of drains and related drainage infrastructure is critically required in such a way to meet the minimum limit of flow velocity and to use as remedy for the problem of overflow of drains. Diversified application of structural and nonstructural measures of LID help to alleviate the prevailing drainage problem of the town.
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    Assessment of Stormwater Drainage System in Assosa Town
    (Addis Ababa University, 2019-01-13) Abdu, Biru; Fiseha, Behulu
    Urbanization is one of the key factors that contribute to urban flooding, which has caused major destruction to the environment, public and private buildings and disrupts public life. In particular, the increase in population and building density influence the change in hydrological characteristics in urban areas. Conversion of pervious areas into impervious areas increases the stormwater runoff quantity dramatically. One way of minimizing urban flooding is to convey stormwater to receiving waters through stormwater drainage systems, which has been practiced in some parts of Assosa town. In Assosa town, drainage problem become an issue during rainy season. This study deals with evaluate the existing stormwater drainage system of Assosa town considering hydraulic and hydrologic parameters in stormwater model. Despite there are many places in the city facing storm drainage problem; Stadium-Mazoria, Stadium-Hibret Bank, Sarbetoch-Anuar, Police commissionEthiopia Hotel and Gebriel-Muluwongel church are areas selected for this study. This stormwater drainage problem has necessitated use of simulation studies for understanding complexities related to the urban flood management; so, the simulation has done by Stormwater Management Model (SWMM). Daily rainfall data is obtained from nearby Assosa meteorology station. The selected extreme daily event was disaggregated into hourly events using reduction formula. Thereafter, the EPA SWMM is used to simulate the response of catchment to rainfall events in which runoff, water depth profile, and outflow hydrograph are obtained. Runoff is also obtained from rational formula for comparison purpose, and for obtaining design intensity a frequency analysis is carried out. LID measures (vegetative swales) also performed to evaluate how LID measures (vegetative swales) influenced urban runoff reduction. The result of this study shows that the problem in the study area caused by insufficient drainage operation, minimum drainage pipe size, improper maintenance and clogging of drainage line by waste material. In addition the results showed that the LID measures are effective in controlling the surface runoff.
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    Assessment of Surface Water Potential to Manage Frequent Drought Disaster (A Case of Dhas District in Borana Zone of Oromia Region, Ethiopia)
    (Addis Ababa University, 2019-06) Alemayehu, Worku; Daniel, Fikreselassie (PhD)
    The study was conducted in Dhas district, which is located in Borana Zone of Oromia region; geographically it is situated 4.00 o -4.39 o N and 38.39 o -39.46 o E with altitude range of 1082 – 1666m a.m.s.l. Total area of the district is 3,183.22km 2 ; its length from West to East is 120 Km and width from South to North is 41km. There is not any river and gauging station in the district; the study was conducted aiming at estimation of surface water potential of the district and evaluation of its sufficiency for managing of drought disaster in the district. The surface water potential assessment of the district was conducted using SCS model with the aid of remote sensing and GIS. The assessment output was contextualized with the study finding of Genale Dawa integrated Master plan study (Dhas district is located in Dawa sub-basin; finding from separate analysis of Dawa sub-basin was referred). For the recent land use/ land cover information of Dhas district; satellite images were downloaded from USGS (United States Geological Survey) website with acquisition dates of December 2018, and the image processing was done using ERDAS Imagine 2015. With the aid of HEC-GeoHMS tool that is specifically designed in the ArcGIS environment to process geospatial data, the curve number was generated using the required information (hydrologic soil group, DEM, LULC map). The district was divided in to twelve sub-watersheds using Global mapped software, and direct runoff estimation was done for each sub-watershed separately; the summation of direct runoff from each sub-watershed was made to get the total direct runoff amount of the district. Thirty years daily grid rainfall data that was collected from NMA was used for the estimation of the direct runoff. Estimation of runoff volume was computed for all thirty years period, and the estimated minimum and maximum runoff volume were found to be 8Mm 3 and 361Mm 3 respectively. Twenty years of forecast was made to estimate the major requirements in the district. Human and livestock’s water requirement estimation based on the population sized of 2039 was computed to be 10Mm 3 / year. The abundant of estimated runoff volume was evaluated, whether it is enough or not to satisfy the major water requirements in terms of managing the frequent drought disaster. As the analysis shows, Dhas district is having sufficient surface water potential that can be developed for managing of the frequent drought disaster in the district. This study was conducted focusing only on the available surface water potential of the district, and its sufficiency for managing of the drought disaster in the district. Its finding is also expected to be an entry point for development of the resource in the large scale. But for its implementation, it needs further feasibility and detail studies.
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    Assessment of The Hydraulic Performance of Existing Water Supply Distribution System: A Case Study on Finote-Selam Town, Amhara Region, Ethiopia
    (Addis Ababa University, 2019-05) Yitayal, Asmare; Geremew, Sahilu (PhD)
    This thesis focused on assessment of the hydraulic performance of existing water distribution system: a case study on Finote-Selam town, Amhara region, Ethiopia. The main objective of this study is to check the hydraulic performance of Finote-Selam town water distribution system by assessing demand and production of water, losses of water, hydraulic parameter. Both secondary and primary data sources were used for this study. Primary data was collected through a face-to-face interview, field survey, and photographs of relevant sites and infrastructures. The secondary data was collected from design document, literatures, journals and reports. Moreover, to analyze existing water distribution system a model was developed by using Water CAD software. The model can be used to identify the zone of higher and lower pressure junctions and velocity though the pipe. The model simulation run was performed for peak and low demand scenarios to analyze the distribution system. For calibration of water distribution system, pipe roughness was considered as the primary calibration parameter in this study. The analysis shows that the current total domestic water demand in town was 1536.75m 3 /day, the water supply coverage was 82.4 % and average per capital domestic water consumption was 37.9 l/c/day. Hence, this result indicates there is a gap between demand and supply. The water loss of the town was 32.18% from the total water production. The apparent loss covers 9.18% while, the real losses covers 23% of the total losses. Simulation results for maximum and minimum pressure and velocity different scenarios were used as a base tool to evaluate the hydraulic performance. Modeling results showed violation of maximum and minimum pressure and velocity criteria at different junctions and pipes. After modifying the existing water distribution system 92.18% of the junctions are in the recommended pressure range and 75.46% of the pipes are in the recommended velocity range. Generally the result of the analysis shows that the overall hydraulic performance of water distribution of the town was poor, which is reflected by low water production rate, low water consumption, and high level of Non-revenue water, low service coverage, not velocity and pressure in permissible range. Therefore, it is significant to rehabilitate and improve the water distribution system capacities, establishing pressure zone, increase pumping rate and drilling additional borehole. In addition providing more attention to water losses reduction policies and strategies are vital for remedial measures.
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    Assessment of the Water Distribution Network of Adama City Water Supply System
    (Addis Ababa University, 2019-12) Dayessa, Leta; Fiseha, Behulu (PhD)
    Water distribution systems are designed to fulfill all requirements of potable water needed for decades. Initial system designs frequently consider any anticipated changes likely to happen. However, as time elapsed they slowly begin to fail to satisfy customers’ requirements. Adama town is the capital city of Oromia regional state. It is also one of the largest city of the region as well as the country with a total population of around 547,987. The main objective of this study was to investigate the state of the existing water distribution system and evaluate the hydraulic performance of the water distribution network with the aid of computer analysis. The peak hour demand was analyzed to verify that the existing sizes of network pipes are sufficiently provide the minimum required pressure at all demand points. The minimum hour demand was analyzed for evaluation of pipe material and strength of the network. To evaluate the existing performance of water distribution system, a model was developed utilizing Water CAD software. The model can be used to solve ongoing problems, analyze proposed operational changes, and prepare for unusual events. Calibration of data on pressure at different location were collected. The model run was performed for different scenarios to analyze the system model, what if conditions. These scenarios are at average day demand, peak hourly demand and Minimum day demand. Comparing representative samples of the distribution main’s pressure field-test with the model-simulated values showed a reasonable and small difference to calibrate the model. The model analysis result showed the different problems of the system, these are oversized and undersized pipes, zero flow velocity and low pressures (negative 87m up to 9m H2O) due to pipe size and topography of the area.
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    Assessment of Water Supply Service Provision Limitations and Its Effects in Case of Masha Town, SNNPR, Ethiopia
    (Addis Ababa University, 2019-05) Kumlachew, Dakito; Fiseha, Behulu (PhD)
    The study focused on the assessment of water supply service provision limitations and its effects in Masha town of south western Ethiopia. In the town, piped water service unavailability and quality was common issues to water users. On the other hand, topography of Masha town is undulating and equity in water service was under question. The study mainly aimed to assess the existing situation of the service, water sources for domestic activities, perception for the lowquality piped water and evaluating the service based on key physiochemical parameters and pressure. Existing water service were assessed based on site visits checklists, questionnaires and interviews of service providers. Out of total 4586 households in the town sample size of 100 were selected using standard procedures. Water quality sample was tested at different locations in water supply system from source to point of supply using photometer, pocket colorimeter and PH meter apparatuses. Pressure of water service in the town were modeled using Water GEMs which was calibrated by actual measured pressure data. The study indicates that existing estimated demand of water for the town was 1477.31 m /day and designed capacity of existing water supply system was 803.52 m 3 /day (54.39 % of current demand). Existing water production amount was 33% of total production capacity and only 15.56% of total capacity were pumped to central reservoir. The cause for limited service capacity were found to be inefficient institutiona l capacity of service providers that leads to inappropriate operation and maintenance. The socioeconomic analysis result depicted that all of households were dissatisfied with piped water service and its primary common cause were service unavailability (66 %) and degraded water quality (33%). Water quality test result of the town showed that average concentration of Fe, Mn, PH and Free Cl2 were 1.430 mg/l, 0.005mg/l, 7.48 and zero respectively. Iron (Fe) was found far high above recommended value of 0.3 mg/l that makes the piped water to be in a very high-risk category. As the model result showed that pipe water pressure was very low in some areas of the town like center of the town where high vertical development was undergoing. Therefore, water supply service of the town has limitations on water quality, availability and equity in the town due to inefficiency of treatment plant and institutional capacity of service providers. The service states has high risk for piped water users and needs water safety planning, household water level treatment practice, upgrading treatment plants and zonal supply for low pressure areas.