Water Supply Distribution System Design

In Holeta Town Wolmera Woreda West (Shewa Zone of Oromia region, Ethiopia)


Bachelor Thesis, 2018
154 Pages, Grade: 1

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TABLE OF CONTENTS

ACKNOWLEDGEMENT

ABSTRACT

TABLE OF CONTENTS

LIST OF TABLE

LIST OF FIGURE

ABBRIVATIONS

NOMENCLATURE

1. INTRODUCTION
1.1 General
1.2 Statement of the problem
1.3 Objective of the project
1.3.1 Main objective
1.3.2 Specific objective
1.4 Expected output
1.5 The research questions
1.6 Significance of the study
1.7 The scope of the study
1.8 Limitation of the Study
1.9 Research Design and Data Collection
1.9.1Research Design
1.9.2Data collection

2 RELATED LITERATURE REVIEW
2.1 Overview
2.2 Water and Civilization
2.3 The Water Supply and Demand Situation of the world
2.4 The Rationales of Urban Water Supply in Africa
2.5 The state of urban water supply in Ethiopia
2.6 The challenges for urban water supply in Ethiopia
2.7 Policy Framework and Potable Water Supply
2.8 Institutional framework and organizational capacity

3 DESCRIPTION OF THE STUDY AREA
3.1 Background
3.2 Location and Topography
3.3 Climate
3.4 Demographic Conditions
3.4.1Population
3.4.2Economic Situation
3.4.3Future Development of the Town
3.5 Basic Social Services
3.5.1Education
3.5.2Health
3.6 Existing Water Supply and sanitary Service
3.6.1Water Supply Service
3.6.2Sanitary Service

4. POPULATION FORECASTING & DESIGN PERIOD
4.1 Introduction
4.2 Design Period
4.3 Population Forecasting Approach
4.3.1 Methods of forecasting population
4.4 Population Data

5. WATER DEMAND ASSESSMENT
5.1 General
5.2 Water demand
5.3 Domestic Water Demand
5.3.1 Population Distribution by Mode of Service
5.3.2 Per capita Water Demand
5.3.3 Domestic Water Demand Projection
5.4 Non domestic water demand
5.4.1 Commercial water demand
5.4.2 Industrial water demand
5.4.3 Institutional Water Demand
5.4.4 Fire Fighting Demand
5.4.5 Non-revenue water
5.5 Water demand variation
5.5.1 Average Water Demand
5.5.2 Maximum Day Water Demand
5.5.3 Peak Hour Water Demand

6. WATER SOURCE AND WELL HYDRAULICS
6.1 General
6.2 Source of water
6.3 Existing source in Holeta
6.3.1 Surface source of water
6.3.2 Ground source of water
6.4 Ground Water Recharge
6.5 Well Hydraulics
6.5.1 General
6.5.2 Factors Affecting the Quantity of Well Water
6.5.3 Well Development
6.6 Well Design
6.7 Well Depth
6.7.1 Design of Length and Size of Screen
6.7.2 Design of Well Screen
6.7.3 Diameter of the well pipe
6.7.4 Diameter of Bore Hole

7. SERVICE RESERVOIR
7.1 General
7.2 Function of service reservoir
7.3 Accessories of Service Reservoir
7.4 Sites of Distribution Reservoirs (proposed)
7.5 Depth of Reservoir
7.6 Determination of Storage Capacity
7.7 Structural Design of service reservoir
7.7.1 Water Tank (reservoir) Design Consideration
7.7.2 Design of circular Reservoir with fixed base and Free at the top

8 COLLECTION CHAMBER AND PUMPS
8.1 Collection Chamber
8.1.1 Determination of collection chamber capacity
8.1.2 Position of Collection system
8.2 Pumps
8.2.1 Purpose of Pump
8.2.2 Selection of a Pump
8.2.3 Centrifugal Pumps
8.2.4 Determination of Pipe Size
8.2.5 Determination of Total Dynamic Head

9 DISTRIBUTION SYSTEM
9.1 Classification of distribution system
9.2 Layout of distribution system
9.2.1 Selection of pipe material
9.2.2 Pipe Appurtenance
9.2.3 Laying of Pipes
9.2.4 Flow Metering
9.3 Analysis of water distribution network

10 WATER QUALITY AND WATER TREATMENT
10.1 Ground water quality and treatment
10.2 Treatment processes
10.2.1 Disinfection
10.2.2 Methods of Disinfection

11 COST ESTIMATION AND ANALYSIS
11.1 Cost estimation for 1150 m3service reservoir
9.2 Cost estimation for 550 m3 service reservoir

12 ENVIRONMENTAL IMPACT ASSESMENT (EIA)
12.1 Introduction
12.2 Description of the potential impacts
12.2.1 Positive impact of the project
12.2.2 Negative Impacts of the project
12.2.3 Mitigation measures

13 CONCLUSION AND RECOMMENDATION
13.1 Conclusion
13.2 Recommendation

REFERENCES

ANNEXES

Annex A. Epanet Analysis Report

Annex B. Summary of Cost Estimation

ACKNOWLEDGEMENT

We want to provide our great full thanks to our advisors, Mr. Zelalem Abera (MSc), Mr. Sabkeebar Ararsa (BSc) next to God; for all his sincere, faithful and immense devotion to help us in providing all the necessary materials which are paramount for our final year project.

ABSTRACT

The provision of clean Water Supply is one of the major factors that greatly contribute to the socioeconomic transformation of a country by improving the health thereby increasing life standard and economic productivity of the society. However, most of the developing country like Ethiopia has still low potable water supply and sanitation coverage that result the citizens to be suffered from water Shortage, water born and water related diseases. A good water supply distribution infrastructure plays a key role for any kind development for a town. This project examined the theoretical framework for the design of an improved water distribution network for Holeta town. The aim of this water supply project is to provide potable water for present and future demand for targeted Holeta town which improve the existing water supply system of the town . The present and future population of the study area was determined and the water demand per day established. The hydrologic, hydro geologic and topographic data formed the basis of the design while laying emphasis on models and theories of pipe networking and performance. The pipe network layout was analyzed with the use of Epanet2.0 software which is based on Hazen William's equation.

Key Words: EPA-NET software, population projection (forecast), pressure head, velocity head, water demand assessment and water distribution network system.

LIST OF TABLE

Table 1: Commercial businesses in Holeta town

Table 2: Distributions of Schools, Students, and Teachers

Table 3: Design periods for various units of water supply

Table 4: Given population

Table 5: Population growth rate

Table 6: Population increase

Table 7: Calculation of the projected population by arithmetic method

Table 8:Calculation of projected population by geometric method

Table 9:Calculation of projected population by incremental increase method

Table 10: Population growth rate of urban population

Table 11:Calculation of projected population by Ethiopian census statistics (CSA) method

Table 12:Summary of projected total population by the four methods

Table 13: Percentage error calculation

Table 14:Summary of population projection for Holeta Water supply project

Table 15: Population percentage distributions by mode of service.

Table 16: Projected per capita demand by mode of service (l/cap/day) (2015-2041)

Table 17: Adjustment factors for climate

Table 18: Adjustment factor for socio-economic conditions

Table 19: Projected domestic water demand

Table 20 Projected water demand for industrial

Table 21: Summary for non-domestic water demand

Table 22: Percentage lost

Table 23: Maximum daily factor

Table 24: Recommended maximum daily demand

Table 25: Recommended peak hour Factors

Table 26: Summary of water demand assessment

Table 27: Values of k and x according to rainfall amount

Table 28: Existing borehole yield

Table 29: Recommended value of screen diameter

Table 30:Recommended well diameter with varies yields

Table 31: Depth of reservoir

Table 32: Analytical calculation of storage capacity for phase I

Table 33: Analytical calculation of storage capacity for phase II

Table 34: Coefficients for Hoop tension (Fixed at base and free at top).

Table 35: Coefficient for vertical moment (For fixed at base and free at top)

Table 36: Coefficients for Hoop tension (Fixed at base and free at top)

Table 37: Coefficient for vertical moment (For fixed at base and free at top)

Table 38: Selected water analysis results

Table 39: Dosing rate and chlorination schedule

Table 40:Concrete mix ratio for C-30

Table 41: Analysis of reinforcement bar consumption

LIST OF FIGURE

Figure 1: Location of Holeta

Figure 2: Summary of water demand assessment

Figure 3: Mass curve graph for phase I

Figure 4: Mass curve graph for phase II

Figure 5: Pressure distribution on reservoir wall

Figure 6: Roof slab reinforcement arrangement

Figure 7: Base slab reinforcement arrangement

Figure 8: Sectional view of reservoir

Figure 9: Epanetdistribution layout analysis


ABBRIVATIONS

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NOMENCLATURE

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1. INTRODUCTION

1.1 General

Water is one of the necessities for human being and for all living things. Water means nothing but just life as it constitutes the major part of the core of the cell, the protoplasm which is about 70% in content of the cell , even though water is a critical necessity for life , it has on adverse effect to life unless and other wise properly handled.

In the world clean water that can be used for domestic purpose is not more than 2% of the natural water resources of the earth. (Source; WHO, 2009).This is very small in amount of wholesome water comparing with the saline water body. As the result of this the world is faced to the shortage of sufficient access of safe drinking water. The developing countries of the world are specially affected by the problem of safe access of drinking water supply. This is because of the lack of technologies and financial supports to utilize their water resources.

Ethiopia is very well known for its enormous potential all of which is generated in its own tertiary and it is still known the water towers in Africa. Access of water supply in Ethiopia is amongst the lowest in sub-Saharan Africa and the entire world, while access has increased substantially with funding from external aid much fill remind to be done to achieve the millennium development goal of halving the share of people without access to water and sanitation. To achieve this goal the Ethiopian government is working to address the problem of safe access of drinking water in different towns of the country

The accessibility to safe water in Ethiopia is about 23 %. That is a very low level when compared with the 54 % average for the Sub-Sahara area (UNDP). In the modern society, it is imperative to Plan and build sustainable water supply scheme which can provide potable water in accordance with their demands and requirements for Human and livestock.The use of water for mankind, plant and animal is universal. Without water, there is no existence of life. The access to a safe and affordable water supply for drinking universally recognized as a basic human need.

Water distribution systems carry drinking water from a centralized treatment plant or well supplies to consumers’ taps. These systems consist of pipes, pumps, valves, storage tanks, reservoirs, meters, fittings, and other hydraulic appurtenances (Drinking Water Distribution Systems assessing and Reducing Risks, page 2). Distribution system infrastructure is generally the major asset of a water utility. The American Water Works Association (AWWA, 1974) defines the water distribution system as “including all water utility components for the distribution of finished or potable water by means of gravity storage feed or pumps though distribution pumping networks to customers or other users, including distribution equalizing storage.”

Therefore; Water distribution networks design and analysis play an important role in modern societies being its proper operation directly related to the population’s well-being. In Holeta whereas a town which is at fast growing stage, is very imperative in modern society to insure the availability of potable water and to plan and design for a sustainable economic suitable pipe network system or water supply schemes.

1.2 Statement of the problem

In Sub-Saharan Africa in general and particularly in Ethiopia beyond the impact of climate change on water availability, other major factors such as: population growth and poor water governance are exacerbating the water supply situation of the countries (Ndaruzaniye, 2011). Based on the 2010 statistical abstract published by CSA there are 970 towns in Ethiopia, 45% of the urban population live in 907 towns with less than 30,000 population. 55 % the urban population live in 63 towns with greater than 30,000 population. They all need piped water supply systems, and local utilities to oversee and operate them. The strategic action is to construct facilities that are well managed and can be expanded to meet the needs of a growing population.

The water supply in Ethiopia, where large portion of the population are challenged due to poor institutional, infrastructural and socio-demographic factors. Moreover, poor accountability and lacks of community participation in water projects were identified as constraints of sustainability (Yacob, et al, 2010). Similarly the study of Aschalew (2009) revealed the absence of community participation and technical constraints are responsible for frequent water interruption and sustainability challenges of urban water supply projects. As a result in spite of the vigorous efforts made to improve the coverage and the system of water supply in country, the functionality rate of water supply source in Ethiopia in 2007 was about 33 % percent (Tamene, et al., 2011). According to the World Health Organization, between 1990 and 2015 the access to improved drinking water sources increased from 13.2 per cent to 57.3 per cent.

In Ethiopia, after the intervention of the Multiple Use Service approach by the non-government projects, the productive role of water to the urban population has got great momentum by the Ministry of Water (Butterworth, et al 2011). But except a mere recognition of the productive role of water, the nature and the factors of productive water use at household level has no yet studied. Even attempts are shown to give much emphasis to link water and urban farming while the domestic home based productive use of water by the urban households are overlooked (James, 2003). Moreover most of the studies conducted in Ethiopia concerning water supply and sanitation have been found to focus on either the supply or demand part of water research which overlooked the equilibrium between urban water supply and multiple needs of water (Kebede, 2003; Zelalem, 2005; and Gossaye, 2007). Similarly studies that are aimed at identifying the factors that affect the demand of water by the households found to pay little or no attention to include the productive demand of water, as a result aggregate demand are used to investigate the determinants of water consumption level. For instance the study of Bihon, (2006), Sileshi, (2008) and Dessalegn, (2012) assessed the main factors for water consumption level, demand for improved water and aggregate water demand respectively without consideration of the productive use of water by the households.

Though the water supply challenges remained intact in various parts of the country, adequate water supply to the urban as well as rural people remained one of the most crucial resources for survival, health and prosperity (WHO, 2006). Particularly to the rural poor water plays a significant contribution as a direct input into agricultural production and as the basis for health and welfare (Narcisse, 2010).

According to the data from the feasibility study, the majority of Holeta town population is partially supplied by town’s water supply system. It is reported that the demand of water couldn’t fulfilled the required demand of water supply. This occurs due to rapidly growth of Population, expansion of the town and development of economy of the town. It is reported that 90% of householders collect part of their total water needs from the town’s water supply system fed directly through private connections or public taps. However, there is insufficient water to meet all demands and the deficit is made up from other sources including wells and water vendors. Though the existing infrastructure is old and in poor condition, interruptions of water supply were occurred from time to time.

1.3 Objective of the project

1.3.1 Main objective

The project aimed to improve the water supply and sanitation system both in quality and quantity at a reasonable cost without affecting the environmental circumstance of the project area.

1.3.2 Specific objective

The specific objective of this project is to:-

- To provide adequate and sufficient water to the town of Holeta.
- To solve the problem of water born disease by providing potable water.
- To develop new water sources, increase the number of pipes lines and construct additional reservoir, and
- To extend the distribution system to those areas of the town.

1.4 Expected output

At the end of design we expected that the water supply and sanitation system of the Holeta town will be improved.

- Potable and sufficient water should be provided
- Problem of water borne disease should be reduced or eliminated.

1.5 The research questions

The general and specific objectives of the study would be achieved by way of seeking answers to the following questions.

1. What are the types of existing water sources and supply in Holeta town?
2. What is the state of existing water supply?
3. Why demand for water exceeds the supply of water?
4. Do the urban communities have willingness to pay higher price for improved water service than the existing water supply service?
5. What are the comments of beneficiaries on the proposed strategy of water supply by the government?
6. What are the major challenges of water supply in the town?
7. What are the factors affecting water supply and consumption of Holeta town?

1.6 Significance of the study

Studying the extent and coverage and dynamics of urban water supply service in holeta helps to identify the pressing problems in service delivery. This study is expected to increase the knowledge and up to date information on the city water supply size and its undesirable impacts on the urban community due to shortage of water supply. It will also serve as a working document to policy makers in the water sector of oromia Regional state (OGRS), especially policy making bodies, and the Holeta town water supply and sanitation authority and the Non-governmental organizations (NGOs) which have interest in assisting Holeta town with financial and technical support in the area of urban water supply. Moreover, the finding will further serve as reference data and it opens avenue for any further investigation in the area, and as a useful material for academic purposes.

1.7 The scope of the study

The objective of this research is to present the fundamental concept of hydraulics applied to holeta town water supply network, in order for municipal officials of the town to a better evaluation and decision making of water distribution and delivery systems. Therefore, the research work was limited the design of water distribution network (from clear water well to distribution end point) of holeta town water supply system in West Shewa Zone of Oromia region of Ethiopia and it mainly focus on the determination of the population served, water demand assessment, distribution system design, selection of source which fulfill the demand of the town with borehole design and environmental impact assessment.

1.8 Limitation of the Study

Due to some major challenges associated with the collection of the data, the study was exposed for some limitations. The first limitation of the study was associated with availability of sufficient information regarding to the study area water supply distribution system network condition which has been designed for town. Secondly the study suffers from lack of sufficient secondary data related with urban water supply design due the inadequacy of works regarding the study area and the poor documentation of the water supply and sanitation authority offices.

1.9 Research Design and Data Collection

1.9.1 Research Design

Generally this study can be seen as a descriptive cross-sectional study with a central task of design of urban water supply system in Holeta town, Wolmera Woreda. The study used a mixed approach with a central premise of; the use of quantitative and qualitative approaches in combination provides a better understanding of research problems than either approach alone. Hence, the mixed approach that is used in this research employs strategies of inquiry that involve collection of qualitative and quantitative data simultaneously to best understand the research problem under investigation. The study was guided by the principles of multiple sources and subsequent crosschecking of information as well as by applying various data collection instrument and analysis techniques- both quantitative and qualitative.

1.9.2 Data collection

A combination of both quantitative and qualitative data from both primary and secondary sources was generated. The primary data was collected from residents of the sample Holeta town, officials of the water supply and sanitation authority and Wolmera woreda water bureau and from field visit. In an effort to supplement the primary data and make this research work more valid and worthy, relevant secondary sources pertinent to the study were consulted. Accordingly, official statistics and reports available in water projects implementing agencies' offices were the major sources of secondary data for this study. Moreover, different written documents both published and unpublished- books, CSA, government, non-government documents, journals and research works in relation to the issue under consideration; government policy and strategy were reviewed to supplement the study as well as to review the overall water supply situation in the study area .

2 RELATED LITERATURE REVIEW

2.1 Overview

A well planned water distribution network is very essential in the development of an area. The network is built to satisfy various consumer demands while meeting minimum pressure requirements at certain nodes. In the design stage it is of interest to arrive at the least-cost solutions that satisfy a set of constraints including demand and pressure requirements. Often it is also of interest to arrive at less expensive solutions that, however, violate slightly the constraints. Accordingly, research interests have been concentrating on the design of water distribution network by using EPANET to search for the optimal combination of decision variables (e.g. head loss and velocity) from a large number of solutions.

This chapter deals with the theoretical overview of potable water supply and distribution. It assesses the sources of water supply, urban water supply accessibility, major challenges of drinking water supply and distribution, potable water supply problems in developing countries in general and in Ethiopia in particular, benefits of access to safe, reliable, adequate and affordable potable water supply and impacts of inaccessibility of water supply and distribution facilities. In addition to these it assesses the Ethiopian government’s water supply and sanitation policy, institutional arrangement and responsibilities at different levels .

2.2 Water and Civilization

Water has been an important factor to the development and survival of civilization. The first great civilization arose in the valleys of great rivers, the River Nile, valley of Egypt, the Tigris Euphrates valley of Mesopotamia, the Indus valley of India and Pakistan and Huang He valley of China. Through the ages people have been compelled to settle in region where water is not deficient in quantity, inferior in quality. Only when supplies failed or made useless by unbearable salt or pollution before them were centers of habitation abandoned. So, man's endeavors to achieve a more desirable relationship with the water of the earth have helped them mould his character and his outlook towards the world around him. People have preferred to meet their water troubles head on rather than to quit their places of abode and industry. So people have applied their creative imagination and utilized their skills and released heroic energy. The ancient well aqueducts and reservoirs of the old world, some still serviceable after thousands of years, at least to the capacity for constructive thinking and corporative ventures which had a part in human advancement. These aqueducts, canals, and reservoirs built by the ancient Romans turned regions along the coast of Northern Africa to be civilized. After Romans left, their water projects were abandoned (World Book, 1984).

2.3 The Water Supply and Demand Situation of the world

Our planet today is at the eve of accepting 7.355 Billion peoples which brings historically unprecedented pressure to the natural resource of the globe (UNPD.WPP, Eurostat: Demographic Statistics,UNSD. Population and Vital Statistics Report (various years), .S. Census Bureau: International Database and Secretariat of the Pacific Community: SDP). In this case Water, which is among the basic natural resource to the livelihood of the rural poor, is exposed to deterioration from time to time. As a result today bringing immediate remedy to the global water crisis became an agenda to achieve the target of the millennium development goals of halving the proportion of people without access to improved water.

Recently thought the global use of improved water sources showed progress from time to time but still 605 million people don't have access to safe drinking water which clearly shows the pressure of the population growth (WHO, 2012). Besides the population pressure of the globe, the water supply and demand gap are exacerbated by various factors of inequitable distribution of water rights, economic resources and uneven resource availabilities (White ford, 2005, cites in Wutich, and Ragsdale, 2008). Even though the problem of water supply is the fact for both urban and rural areas, the world is still predominated by the world rural population which lack access to improved water as compared to that of urban population. As shown in the Figure 2.2. It is only 3.55 % of the world urban populations are considered to be without access to improved water. Unfortunately this number is much higher for the rural population of the world for whom the population without accessibility to improved water source reached 15.423% which is five time higher than the urban population.

The world's water security situation is basically influenced by two grand driving forces: pressure on the supply of water and pressure on the demand for water. Pressures on water supply include; impact of climate change, multinational use of water basins and aquifers, poor water supply infrastructure and intermittency are just only listing some of the major once. On the other hand pressured on the demand side includes; population growth and distribution, agriculture (which currently accounts 70% of all water use), changes in diet and industry (20% of global water use) are the prime challenges for the spontaneous increment of water demand of the world today (REA, 2010). Hence identifying these two grand drivers of water supply and demand situation, the options for tackling these challenges will revolve around them. Therefore, integrating supply orientated and demand orientated measure through policy, governance and regulation, cultural change and institutional reform, as well as through better approaches to management and application of new technologies and techniques are promising measures if the two drivers are required to be tackled and the world water situation needed to be improved (ibid).

According to the World Health Organization and UNICEF, in 2010, 89% of the world’s population used drinking water from improved sources (54% from a piped connection in their dwelling, plot or yard, and 35% from other improved drinking water sources), leaving 780 million people lacking access to an improved source of water (WHO/UNICEF, 2012).

The world met the United Nations’ Millennium Development Goal (MDG) drinking water target to halve the proportion of people without sustainable access to safe drinking water by 2015 in 2010, 5 years ahead of schedule (WHO/UNICEF, 2012). More than 2 billion people gained access to improved water sources from 1990 to 2010. However if current trends continue, 605 million people will be without an improved drinking water source in 2015 (WHO/UNICEF, 2012).

Access to safe drinking water is measured by the percentage of the population having access to and using improved drinking water sources.

Improved drinking water sources should, but do not always, provide safe drinking water, and include:

- Piped household water connection
- Public standpipe
- Borehole
- Protected dug well
- Protected spring
- Rainwater collection

Unimproved drinking water sources include:

- Unprotected dug well
- Unprotected spring
- Surface water (river, dam, lake, pond, stream, canal, irrigation channel)
- Vendor-provided water (cart with small tank/drum, tanker truck)
- Bottled water*
- Tanker truck water

* Bottled water is not considered improved due to limitations in the potential quantity, not quality, of the water.

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Figure 1: World Improved water source (% of population with access) in 2015

Source: computed from WHO/UNICEF (JMP) for Water Supply and Sanitation (wssinfo.org )

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Figure.2: World without Improved water source (% of population without access) in 2015

Source: Source: Computed from WHO/UNICEF, 2015. (wssinfo.org )

2.4 The Rationales of Urban Water Supply in Africa

In the year 2000 all most all African countries were adopted the millennium development goals and seeks to "halve by 2015 the proportion of people without access to safe drinking water and sanitation" (Todaro and Smith, 2011). However in Sub-Saharan Africa it is anticipated to rich the target to the year 2040, after 25 year from the expected target (Sutton, 2008).That is why still, around 276.5 million of the people living in sub Saharan Africa are left without access to safe water with a majority of them being women and children living in rural households (WHO/UNICEF (JMP) for WSS , 2015). SSA has the lowest drinking water coverage and the lowest sanitation coverage in the world (WHO, 2012).

With only 56 percent of the population enjoying access to safe water, Sub-Saharan Africa lags behind other regions in terms of access to improved water sources. Based on present trends, it appears that the region is unlikely to meet the target of 75 percent access to improved water by 2015, as specified in the Millennium Development Goals (MDG). The welfare implications of safe water cannot be overstated. The estimated health and time-saving benefits of meeting the MDG goal are about 11 times as high as the associated costs. Monitoring the progress of infrastructure sectors such as water supply has been a significant by-product of the MDG, and serious attention and funding have been devoted in recent years to developing systems for monitoring and evaluating in developing countries. Piped water reaches more urban Africans than any other form of water supply-but not as large a share as it did in the early 1990s. The most recent available data for 32 countries suggests that some 39 percent of the urban population of Sub-Saharan Africa is connected to a piped network, compared with 50 percent in the early 1990s. Analysis suggests that the majority of those who lack access to utility water live too far away from the distribution network, although some fail to connect even when they live close by. Water-sector institutions follow no consistent pattern in Sub-Saharan Africa. Where service is centralized, a significant minority has chosen to combine power and water services into a single national multi-utility urban water sector reforms were carried out in the 1990s, with the aim of creating commercially oriented utilities and bringing the sector under formal regulation. One goal of the reforms was to attract private participation in the sector.

In Africa despite there are recently positive trends regarding the water supply and coverage, still the problem is pervasive in the region and remains unsolved permanently. Even in the region for many of those who supposedly already enjoy an improved service, the reality is one of poor continuity, poor quality and premature failure. As a result Tens of millions of people face continuing problems with systems that fail prematurely, leading to wasted resources and false expectations (Lockwood, and Smits, 2011). According to the report of (WHO/UNICEF, 2011), 84% of people without access to improved drinking water sources live in rural areas of the region. In Africa the sustainability of water projects still remains the major challenge for continued provision of water to the rural population. The Water Supply Network indicates an average rate of non-functionality for hand-pumps in sub-Saharan Africa is 36% which is shameful wastage in the sector. Due to this fact huge amount money which estimated to be hundreds of millions of dollars over the last 20 years are wasted. Having recognizing such trends community managed projects has been envisaged but still the problem remains intact due to lack real participation of the community (RWSN, 2009, cited in Lockwood, and Smits, 2011).

Looking in to the trends of urban improved water coverage, in East Africa for instance the progress is still remained undone. As shown in the Figure 3 below only Djibouti reaches around 97.3% of urban improved water coverage, this percentage is even very high as compared to the urban provision of the other east African as well as sub Saharan African countries. Unfortunately among the East African countries, Ethiopia has the lowest improved water coverage estimation as compared to Uganda and Djibouti. Even though the prospects of urban water supply have shown some progress, still the trend fails to converge with the urban water supply.

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Figure 3: urban Improved Water Coverage in sub-Saharan African and East Africa

Source: Computed from WHO/UNICEF, 2015.

2.5 The state of urban water supply in Ethiopia

The water supply and sanitation sector in Ethiopia is one of the least developed and is mostly characterized by service deficiency of physical infrastructure as well as by inadequate management capacity to handle policy and regulatory issue and to plan, operate, and maintain the service.

Regarding this, World Bank Group (2005:2) stated that though Ethiopia is often referred to as the “water tower” of Africa, only a quarter of the country’s population have improved access to water sources. Rushing streams from the Ethiopian highlands form tributaries of famous Blue Nile, Tekeze, Awash, Omo, Wabeshebele and Baro-Akobo-rivers which flow across borders to neighboring countries. Six billion cubic meters of water run out of Ethiopia as the Blue Nile River to the Sudan and Egypt. But as recurrent drought drives more and more rural people from their traditional farmlands to urban centers, Ethiopia faces growing urban water crises.

Ethiopia has one of the highest urbanization growth rates in the developing World. According to data obtained from the Central Statistical Authority, the country’s urban population was growing at 4.8 per cent per annum between the 1995 to 2000. The urban population in Ethiopia in 1984, the first census period, was 4.3 million forming 11 per cent of the total population. In 1994, the second census period, the urban population was 7.4 million. Total urban population had increased by 12 per cent from that of 1984. In terms of urban centers, in 1984, Ethiopia had 312 urban centers with population of over 2000. In 1994, the second census period, the urban centers in the country grew to 534 registering an increase of 71 per cent over that of 1984 though the definitions of the two censuses are not the same (Tegegne, 2000:2).The growth has been much higher for some intermediate towns. In 2000 17.6% of Ethiopia’s population or about 11 million people live in about 927 cities and towns of different sizes and categories. Currently, in 2005 about 20.1% of urban populations live in cities and towns of different sizes and categories.

The rapid growth of urban population has placed tremendous pressure on the management capacity of municipalities for service delivery and local economic development. This phenomenal growth has also burdened many municipalities with the problems of inadequate housing, poverty and unemployment, inadequate water and electricity supply, and poor sanitation systems. Available data also indicate that in the next 25 years (1994-2020), nearly 30 per cent of Ethiopia’s population will live in cities. This kind of rapid urban population growth will inevitably call for huge investments in housing, urban infrastructure, water and electricity supply, sanitation systems and environmental protection programs and programs to alleviate poverty and unemployment in the cities. This implies that the challenge will require well trained municipal management and resource capacity, responsive urban governance and well trained and motivated personnel and sustaining services such as water, electricity supply, local revenue collection and administration to meet the ever growing demand for better and more quality services and infrastructures.

Because of this population pressure and other factors as per official statistics, coverage of water and sanitation service in Ethiopia is very poor, among the lowest in the world, especially for rural areas. Among the key indicators for International Development Goals, Ethiopia’s performance on “sustained” access to safe water sources and sanitation services is one of the worst in the region.

According to the figures given by Tegegne (2000:16), the amount demanded is much higher than the supply. That is, in 1998 the amount supplied by Addis Ababa Authority was only 62 per cent of the amount demanded. With regard to the distribution of water, the Welfare Monitoring Survey of 1996 estimated that 36 per cent of the households use own tap while 61 per cent use public tap or “public fountain”.

Berhanu and Said in Genenew (1999:8) also figured out that only 27 per cent of the populations of Ethiopia have access to safe water and 10 per cent have access to sanitation while these figures stand 71 per cent and 30 per cent for safe water and sanitation respectively for low income countries.

There is also regional variation both in rural and urban areas such as Addis Ababa, Dire Dawa and Harari in particular showing more per centage of population with access to safe source of water and sanitation. Afar, Benishangul-Gumuz and Gambella regions show the low per centage of population with access to safe water. For instance, in towns such as Mekele, Nazareth, Bahirdar and Harrar only 33.6, 38.6, 42.9 and 57.8 per cent of the housing units, respectively, had a private or shared water meter in 1994. The water supply in small towns is extremely low.

Regarding this, the World Bank group (2005:2) mentioned that towns in the 2,000 to 50,000 population range face special challenge in the provision of their WSS services. The demand for differentiated technologies-piped water supply in the core, alternative technologies in the fringe areas- and the often rapid unpredictable water demand and spatial growth require planning, design, and management skills that exceed community based management approaches. But unlike larger towns or cities, these smaller towns often lack the financial and human resources to independently plan, finance, manage and operate their WSS systems. This implies that a key challenge for Town WSS is to allocate limited government resources amongst a large number of dispersed towns. The following table 2.1shows the coverage for water supply and sanitation in Ethiopia.

Table 2.1: Coverage for Water Supply in Ethiopia

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There are also variations across urban areas. Based on the official statistics, conditions with access to safe water in urban areas is higher in terms of coverage, with about 84 per cent having access to safe water sources, though there are some variations across different town size classes. This, however, needs to be treated with caution as most households rely on shared services, consumption levels are very low, seasonal variability is very high and unscheduled disruptions to services are very common. Small towns with less than 2,000 populations have access levels of only 40 per cent and those with less than 10,000 populations have a level of around 60 per cent. Interestingly, except for the very small ‘towns’ with less than 2,000 population, most other towns have some form of piped systems, and access to piped systems is over 75 per cent in towns with more than 10,000 population.

MWR (2002:4) distinguished three categories of towns outside Addis Ababa. Rural towns: towns with less than 2,000 population where 60 per cent of towns have piped system, but coverage levels in terms of population with access to piped system is low at about 20 per cent. Small towns: towns with 2 to 10,000 population that mostly have piped systems but the access to piped system is only about 50 per cent and medium and large towns all have piped systems but do require some improvement in access. Even among these towns “access” is largely confined to yard taps or shared connections, with the resultant implications for cost recovery and financial viability. The following table 2.2 shows water supply status in urban areas.

Table 2.2: Water Supply Status in Urban Areas, 1994

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Source: WSP, 2002:5

2.6 The challenges for urban water supply in Ethiopia

Ethiopia has plenty of water resources but the available water is not distributed evenly across the country and the amount varies with seasons and years. The challenge in any situation is to maintain a year-round supply that is adequate to meet people’s needs. To ensure that supply meets demand the source of the water must be carefully chosen, taking into account present and future demand for water, and the costs. The cost of water supplies is heavily influenced by the distance of reliable water sources from towns. The challenge for many towns is finding nearby water sources.

Planning for present and future demand has to consider population growth. The demand for water is increasing in cities and towns due to an ever-growing population and the migration of people from rural areas to towns in search of jobs and a better life. There are also increasing demands from industrial and commercial development. The quantity of water required for domestic use depends not only on the number of people but also on their habits and culture, and on how accessible the water is. On average, Ethiopians in urban areas use only about 15 litres of water a day for their needs (MoH, 2001; Ali and Terfa, 2012).

There is a difference between the WHO estimate and the daily water consumption per person in Ethiopian towns. The shortfall is perhaps due to the shortage of private water taps, which means that people have to collect water from public taps. If people have a piped water supply in their home they are likely to wash and bathe more frequently, and some may have water-using appliances like washing machines. As water supply systems improve and access increases, the consumption of water will increase also. It is therefore important for water supply planners to consider the expected changes in society and in living standards. Planning of water supply projects should also consider the water requirements of schools, hospitals and other health facilities, churches and mosques, hotels, public washrooms, and other community facilities.

The government of Ethiopia has set targets of 100% coverage of safe water supply in urban areas and 98% coverage in rural areas. These targets originated from the Universal Access Plan of 2005 and the Growth and Transformation Plan of 2010, and have been adopted by the One WASH National Programme (OWNP), which is being implemented with major funding from government and international donors (FDRE, 2013). The planning criteria for water supply coverage in the OWNP are:

- rural water supply: 15 litres/person/day, within 1.5 km radius
- urban water supply: 20 litres/person/day, within 0.5 km radius (FDRE, 2013).

As you can see, these figures are still below the WHO recommendation and are more than current usage, indicating the scale of the challenge ahead. The targets for Ethiopia are that 4.4 million urban inhabitants and 26.6 million rural inhabitants, nearly 30,000 schools, and more than 7500 health posts/centres will gain access to safe drinking water (FDRE, 2013).

Another key issue in urban areas is the reliability of the water supply. Consultations with the poor also highlighted this aspect vividly. Limited available information suggests that reliability of supply is likely to be quite poor, both in terms of quantity and frequency. Regarding access for the poor on the whole, relative level of access to water and sanitation in urban areas is estimated to be high in Ethiopia. However, in some larger urban centers the poor may lack access. The aforementioned information indicates that as a result of low level of development a significant proportion of the total urban population of Ethiopia in particular and total population of Ethiopia in general have no access to safe and adequate potable water supply. They still restrict themselves to use what nature has provided them with in the form of springs, rivers, lakes, ponds, traditional hand dug wells and rain water which are often unsafe, cause health hazards and are at considerable distance from households. Among the main reasons given for the slow pace of progress in water supply services in Ethiopia, the following are net worthy: lack of comprehensive legislation; inadequate investment resources; lack of a national water tariff policy and the absence of beneficiary participation and community management (Dessalegn, 1999:12). In relation to this, MWR (2002:13) stated that issues of poor sector capacity and low level of expenditures for WSS are interlinked and lead to a vicious circle – as low level of investments create low demand for technical and manpower inputs in WSS sector, the capacity remains underdeveloped. The resulting low sector capacity, means low allocations and expenditures are curtailed. The sustainability of water supply facilities mainly depends on a timely and regular maintenance and operation of the system. However, in most developing countries, including Ethiopia, it has been found out that operation and maintenance (O&M) of water supply facilities is in a poor state of condition and the sustainability of the scheme is at stake. Regarding this, MWR (2002:13) identified the following underlying problems:

- Inappropriate tariff setting without emphasis on full cost recovery;
- Lack of clear guidelines for urban tariff setting including issues related to fairness, and financial sustainability;
- Inappropriate or lack of institutional incentives for urban WSPs to achieve financial viability and improved operational performance;
- Poor technical and financial capacity among the urban service providers that leads to high levels of unaccounted for Water (UFW); and
- Poor or nonexistent consumer services and grievance handling system that leads to a lack of willingness to pay user charges.

According to the feedback gathered from the participants of the workshop conducted in Bahardar in April 1999, the following were pointed out to be the main causes or challenges for the O & M problems in Ethiopia in order of importance:

- Poor organizational setup in the sector coupled with the absence of trained manpower;
- Low community awareness regarding the importance of clean water;
- Absence of adequate repair parts, spare parts, and hand tools;
- Financial shortage to support O & M , and the limited funds that are available are used for new installations;
- Low participation of the beneficiaries in the decision making process;
- Substandard designs, poor construction quality, and inappropriate technology;
- Absence of coordinated supervision and monitoring mechanisms;
- Unwillingness to pay for services;
- Low attention paid to local skills and minimal support to Artisans and private sector (Abay Engineering PLC, 2000).

There are still many challenges ahead but the following changes will all contribute to future success:

- an increase in funds for the expansion of water supply services to satisfy the demand of growing populations, particularly in small towns
- a reduction in bureaucracy to facilitate the spending of funds that are committed (currently only around 60% of budgeted finances are actually spent)
- a reduction in the turnover of personnel, and an increase in human resource capacity and expertise at different levels
- better coordination between the different stakeholders (for instance, there is lack of coordination between the water sector, telecommunication department and the road authority; because of this, water pipes are frequently damaged during activities such as laying down telephone and internet lines, and during road construction)
- the presence of more experts to monitor sector performance at all levels
- Better information management systems, giving early warning of requirements.

2.7 Policy Framework and Potable Water Supply

Before 1999, water resources development, in general, and the provision of potable water supply, in particular have been carried out without any policy framework and were not well coordinated in the country. However, since 1999, it seems due attention has been given by the Ethiopian government to alleviate the problem of access to safe water supply and achieve rapid socioeconomic development through better health care and productivity of its people by formulating the country’s water resources management policy in 1999.

The water supply and sanitation policy is an integral part of the country’s water management policy. According to the policy document (1999), the policy is believed to provide and impetus for the development of water supply for human and animal consumption. It focuses on increasing the coverage, quantity, reliability and acceptable quality, taking the existing and future realities of the country into consideration. Upon implementation, the policy is expected to achieve the objective of the Ethiopian people to attain adequate, reliable and clean water service that meets the water user’s demand.

The policy of supplying free water to any group except for emergency, leads in practice to an unfair situation. Since there are no enough funds to provide such free services, the rural and urban poor are the first to suffer. A better and much more equitable way would be to collect water charges from consumers and then improve and expand the system. Accordingly, the policy envisages supplying improved potable water service for urban areas with tariff structures that are set based on “full cost recovery and self reliance”.

Apropos this issue, Alebel (2004) stated that a full cost recovery program has the advantage of providing incentive for proper use; reduces waste and excessive consumption of water resources. Besides, it helps to release funds for other investment programs. The policy considers water as a social and economic good, and it is an integrated one. Full cost recovery requires charging consumers so as to cover the full cost of project construction as well as the operation and maintenance of providing the service. Water development investments by their nature require huge amounts of money.

This implies that charging consumers for water should be done carefully. If prices are set too low, revenues may not be sufficient to cover the full costs of supplying water. If, on the other hand, they are set too high, households may not be able to afford consuming the new 27 improved water, and again revenues will not be sufficient to cover the full cost. In relation to this, Alebel (2004) suggested that setting the required tariff, information on the ability and willingness of the consumers to pay for such services are essential. In other words, to cover the full costs and sustain the service, revenue should be collected from the sale of the water based on the tariff that considers the full recovery of the cost, on the one hand, and the fairness and willingness of the consumers that are supposed to be served, on the other.

Therefore, the policy for increasing the coverage as the proper use and sustainability of the service requires implementation of a cost recovery system, which can be either full or partial cost recovery. That is, in order to implement the existing policy for the provision of water supply in urban areas of the country fairness of the tariff, willingness to pay for the service and efficient management of the resources of the utility office need to be examined.

2.8 Institutional framework and organizational capacity

Although urban water supply services began during the Imperial regime, it was not until 1971 that a body responsible for all aspects of water use and development in the country, the Water Resources Commission, was established. The Awash Valley Authority was setup in 1962, but its duties were to plan and promote investment activities within the valley. The commission was given a wide mandate and entrusted with the responsibility of planning and utilizing the country’s water resources including household consumption. In the early 1980, the government pledged to implement the UN initiated International Drinking Water Supply and Sanitation Decade, which in Ethiopia ran from 1984 to 1994, coinciding with the governments ten year plan, which set an ambitious target for the provision of safe water supply to the rural areas. At the beginning of the 1980, less than 6 per cent of the rural population and 19 per cent of the population in the twenty major towns had access to clean drinking water. At the end of the plan period, the coverage for rural areas was to reach 35 per cent and for the urban areas 85 per cent. While the record of achievement was not as high as planners had hoped for, considerable progress was made in 1980, (Dessalegn, 1999:11 cetid as; Assefa Dallecho).

The Water Supply and Sanitation Authority (WSSA), a division within the Water Resources Commission, was established in 1981. Between then and 1992, WSSA was the principal agency responsible for water development in the rural areas and all urban areas except Addis Ababa. By 1990, a total of 210 urban water systems serving about 3 million people came under WSSA’s responsibility. Likewise, the authority was responsible for providing support and maintenance to cover 6000 rural water schemes serving over 4 million people throughout the country (Dessalegn, 1999:12).

With the establishment of regional administration under the Transitional Government of Ethiopia in 1992, Water development programmes became decentralized. At present, the Regional administrations are responsible for the development, operation and maintenance of rural and urban water supply systems in their regions. WSSA has also been absorbed into the ministry of water resources and become the Department of Water Supply and Sanitation (DWSS). However, the relationship between DWSS (or MWR) and the regions appear to be unclear and the way decentralization of water development will be carried out in practice needs to be spelt out in more detail. Within the emerging framework of demand responsive approaches, the role of government is changing from service provision to facilitating and providing an enabling environment.

Within the decentralization framework in Ethiopia, different responsibilities are emerging for different levels of government: policy and strategy development, project implementation and monitoring and evaluation. At the federal level the responsibility for the water sector is with the Ministry of Water Resources (MWR). Responsibility for ensuring the provision of these services is with the regions and will eventually be with woredas (MWR 2002:6).

At the regional level, Regional Water Bureaus (RWBs) along with their other responsibilities for water resources are also responsible for water and sanitation. In some of larger regions, woreda water offices with small staff of two persons or so have been established. This trend for the woreda level is intended to be strengthened in the coming years. Within the Ethiopian context, NGOs have been important players in the WSS sector. For rural water supply schemes (RWS) Ethiopia Social Rehabilitation and Development Fund (ESRDF) has also played a major role in recent years (WSP; 2002:7).

As MWR (2002:7) documented, in Ethiopia, a number of different forms of service providers exist with considerable inter and even intraregional variations, including: Addis Ababa water and sewerage Authority (AAWSA), Urban /Town Service Unit (TWSU), Some Scheme Water Boards (SWB) and at the very local level Water Board (WB) and Village Water and Sanitation Committee (VWSC). There has been limited involvement of the private sector to date, though there is an emerging interest. With regard to the financing issue, though the National Water Policy envisages financing from domestic financial institutions. So far sector financing has been largely through: budgetary allocations, external debt or grants from bilateral donors and international NGOs, sometimes provided either directly to communities or local levels of government and more recently other off-budget mechanisms such as ESRDF. MWR also proposes to establish a Water Resource Development Fund (WRDF). It is envisaged that the WRDF will pool the government and donor resources and channel in line with the overall sector policy. In the long-run it is visualized that WRDF will also mobilize additional resources (MWR, 2002:9).

With decentralization, a large share of federal resources is transferred to regional governments and regional and woreda governments allocate funds for the WSS sector from their own budgets. However, an effective decentralization process is constrained by: the lack of medium term federal subsidy estimates and donor practices that inhibit multi-year planning. WSS allocations within this emerging decentralization framework depend on the planning process at these levels and the issue of relative preparedness of the WSS sector at this level will be an important determinant (ibid).

Based on available information, preliminary and indicative estimates suggest that the current level of funding allocation to the sector is about 34 million USD per annum. Clearly, to achieve improvements in poverty reduction and other development goals 30 water supply and sanitation deserves an equal attention as other sectors such as education, health and roads. However, WSS allocations leave a great deal to be desired as compare to these sectors. This more likely reflects a lack of sector readiness to absorb resources rather than a low priority for water supply and sanitation. The priority actions and programs with in the sector will have to focus on strengthening overall sector capacity along with the specific investment strategies linked to coverage targets. (MWR; 2002:10). From this review of related literature we would understand the pertinence of and the different approaches to urban water supply.

3 DESCRIPTION OF THE STUDY AREA

3.1 Background

The Oromia regional state water resources development bureau is one of the governmental organizations which established to improve the water supply and sanitation situation of the region and the project area suited in one of the lack of potable drinking water of the region due to deprived and insufficient amount of clean water.Holeta water supply project is one of the projects aimed to achieve the millennium development goal of Holeta town, in the Oromia region of Ethiopia. The project aims to improve the living conditions of the town by rehabilitating existing systems and extending the water supply infrastructure as well as providing adequate training for Town Water & Sanitation Services (TWSS). The project will develop new water sources (deep and shallow wells and springs), increase the capacity of pipelines and reservoirs, extend the distribution system to those areas of towns not currently serviced, and provide technical assistance to the TWSS.

3.2 Location and Topography

Holeta is located in West Shewa Zone of Oromia National Regional State about 34km from Addis Ababa. The town is situated along the main Addis Ababa to Nekemete road. Geographically it is located at latitude 10002’92’’ north and longitude 44060’22’’ east. Presently, Holeta is the capital of Wolmera Administrative district. The total area of the town is estimated to be 5550 ha and is divided into four urban and five rural Kebeles. The town lies between elevations of 2320 and 2460 m.a.s.l.

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Figure 1: Location of Holeta

Source : Holeta Town Feasibility Study

3.3 Climate

Holeta town is characterised by high mean annual rain fall of 1367 mm. The highest rainfall occurs in June, July, August and September with March and April being the driest months.

The mean monthly temperature of Holeta ranges from 12.30C- 15.90C. The minimum and maximum temperature varies with in 1.60C-8.90C and 19.60C-24.70C, respectively. The lowest temperature recorded during the months of December, January and February. The highest temperature recorded during the spring season (February, March, April and May). The variation of the temperatures is minimal, which is typical for the climatic region. According to the climatologically classification, Holeta town is climatically classified as" Dega Rainy” climate.

3.4 Demographic Conditions

3.4.1 Population

The 2007 national census reported a total population for Holeta of 25,593, of whom 12,605 were men and 12,988 were women. The majority of the inhabitants said they practiced Ethiopian Orthodox Christianity, with 73% of the population reporting they observed this belief, while 20.44% of the populations were Protestant, and 5.43% were Muslim.

According to the 1994 national census, this town has a population of 16,800. The 1994 census reported this town had a total population of 16,785 of whom 8,040 were males and 8,745 were females. Using this as a base, the 2008 population is estimated at 33,099.It is the largest of three towns in Wolmera Woreda.

3.4.2 Economic Situation

Holeta is the capital of Wolmera Woreda and, therefore, is an important administrative and communication centre with a population of more than 33,000 inhabitants. Holeta is a major transit centre and it is located on the main road from Addis Ababa to Nekemete. The town also serves as a major marketing centre with thousands of rural people flocking into the town. The major economic activities according to the town’s administration office are trading, hotel services and small-scale industries.

Table 1: Commercial businesses in Holeta town

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Source: Holeta Town Municipality, 2007

According to the development plan of Holeta, social and personal services are the dominant employment sectors followed by trade and tourism. The status of Holeta as the capital of the district means that administrative and law enforcement institutions are centred in the town.

Manufacturing is the other dominant sector providing employment. It is mostly based on grain milling activities but the potential for diversification and growth is high. Construction is a relatively young sector linked to the growing demand for modern buildings.

3.4.3 Future Development of the Town

A Master Plan for the town was prepared in 2008. According to information from the town’s administration office the economy of the town will improve significantly. It is expected that flower farming and small scale industries will grow substantially followed by the building sector and hotel industry. Trading and transport sectors are also predicted to grow significantly.

3.5 Basic Social Services

3.5.1 Education

Educational services in Holeta comprise kindergartens, first cycle schools, second cycle schools, high school, preparatory school, technical college and one private college.

Table 2: Distributions of Schools, Students, and Teachers

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Source: Holeta Town Education office, 2007

3.5.2 Health

One health centre and eight private clinics are found in Holeta town. The health centre has 14 beds.

3.6 Existing Water Supply and sanitary Service

3.6.1 Water Supply Service

The primary source of water is from three boreholes drilled in 1997, 2000 and 2007 with a cumulative output of 12.3l/s at the moment. Water is pumped from the boreholes to a 300 m3 and 50m3 reinforced concrete reservoirs from where it gravitates into the distribution system. The water is distributed to the consumers through a total of 2,529 private connections and 24 public fountains.

Water shortage is the major problem with the existing system. Accordingly domestic supplies are supplemented from secondary sources from the river, small springs and hand dug wells.

According to data from the Water Supply Service Office, the majority of households in Holeta are partially supplied with water from the town’s water supply system. It is reported that 90% of householders collect part of their total water needs from the town’s water supply system fed directly through private connections or public taps. However, there is insufficient water to meet all demands and the deficit is made up from other sources including wells and water vendors.

3.6.2 Sanitary Service

The overall sanitation of the town is poor and sanitation associated diseases are prevalent. There is no system for collecting, transporting, and dumping waste in the town.

- Solid Waste Management

The majority of households have no containers for storing garbage. There are few garbage collection facilities located in the community, therefore, residents of the town dispose of domestic waste in any open spaces especially on the road verge and in drainage ditches. There is a temporary sanitary land fill along main highway to Nekemte.

- Liquid Waste Disposal

There is no liquid waste disposal system in the town. Waste resulting from bathing and other domestic washing activities is almost entirely thrown out into the streets. There is no specific site for liquid waste disposal.

- Toilet Facilities

Most of the excreta disposal facilities in Holeta Town comprise pit latrines which are frequently poorly constructed, offensive and over filled. According to the town’s municipality the majority of households use toilets in their own compound and the prevalence of open defecation is also significant and demands improvement.

- Sludge Disposal Method

The municipality does not own a vacuum truck for sludge disposal. However, according to the town’s administration the municipality brings a vacuum truck from Addis Ababa and provides sludge disposal service for households by charging 310 Birr for a single service. According to the information from the municipality during the field visit by the Consultant, most households are unable to afford this facility and few households employ the service. Many households dig a new pit when the old one is filled. Currently there is no proper sludge disposal site and sludge is disposed in the farm land outside the town.

4. POPULATION FORECASTING & DESIGN PERIOD

4.1 Introduction

The economic design period of the components of a water supply depends on their life, initial cost, rate of interest on loan, the ease with which they can be expanded of the likelihood that they will be rendered absolute by technological advances. In order to design the parts of water system, the flow at the end of design period must be estimated.

The current development plan for Holeta Town was prepared in 2008 by Oromia Regional state Urban Planning Institute. The development plan shows that there are areas allocated for residential, commercial, industrial and service-giving institutions. With the growth of the private sector in the economic activity of the town, there will be a high demand for basic services among which water is the prime necessity.

The proposed town development plan supplemented with on-site observation, topographic maps and consultation with the local community, governmental and non-governmental organizations are among the basis for water demand computation and design of future water supply system.

It is necessary to fix the design period and forecast the population of the area in the design of any water supply scheme. Water supply projects are usually designed for a certain period after the completion of construction works in order to satisfy the population demand.

4.2 Design Period

Design period is the number of years for which the design of water works has been done. Before designing & construction of water supply scheme, it is necessary to assure that the water works have sufficient capacity to meet the future water demand of the town for the fixed design period. Therefore the number of years for which the design of the water works has been done is called design period. The design period, however, should neither too long or too short. Mostly water supply schemes have design period of 22-30years.

The different elements of the treatment & distribution systems may approximately be designed for different flow criteria as shown in the table below.

Table 3: Design periods for various units of water supply

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Source (Dr.B.Cpunmia, water supply Engineering)

The design period of a water supply scheme can be limited by the following factors

1. Funds available for the completion of the project
2. Life of the pipe and other structural materials used in the water supply scheme.
3. Rate of interest on the loans taken to complete the project.
4. Anticipated expansion rate of the town.

Since Holeta is the capital of WolmeraWoreda it is expected to grow in the future and its water supply system should have a small design period and we adopted 25 years depending up on the life span of the material and anticipated expansion of the town.

4.3 Population Forecasting Approach

After the design period has been fixed, the population of the town in various periods has to be determined. As population of the area increases in the future, the correct present and past population data have to be taken form census office to determine design population of the area. The future development of the town mostly depends on trade expansion, development of industries and surrounding country, discoveries of mines, construction of rail way station etc. These elements may produce sharp rises, slow growth, and stationery conditions or even decrease the populations. The populations are increased by births, decreased by deaths, increased or decreased by migration and increased by annexation. These all four factors affect the change in population. The correct present and past population can be obtained from census office. Knowing the present population from the recent census is possible to design or forecast future population of the town.

4.3.1 Methods of forecasting population

By considering growth rate of the town we use the following different methods of population forecasting to asses and estimate the future population of the town:

A. Arithmetic increase method

B. Geometric increase method

C. Incremental increase method

D. Method used by Ethiopian static authority

A. Arithmetic increase method

This method is based on the assumption that the population is increasing at constant rate, that is the rate of change of population with a time is constant. Generally, the method is applicable to large and old cities.

Abbildung in dieser Leseprobe nicht enthaltenAbbildung in dieser Leseprobe nicht enthalten

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B. Geometric increase method

The method is based on the assumption that the percentage increase in population remains constant. It also known as uniform increase method. The increase is compounded over the existing population. This method is mostly applicable for growing towns and cities having vast scope of expansion.

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C. Incremental increase method

In this method the population in each successive future decade is first worked out by the arithmetical increase method and to these values the incremental average per decade is added. Since the method combines both arithmetic as well as geometric increase method, it improves the few results that are obtained by arithmetic increase method. Hence it gives satisfactory results.

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D. Method used by Ethiopian statistics authority

The Ethiopian statistic authority uses the formula pn=poekn for most water supply project in the country to project population at the end of required decade/year.

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Due to given population data Arithmetic increase, Geometric increase, Incremental increase and Ethiopian statistical authority methods are used for population projection of Holeta town.

4.4 Population Data

The number of population of the town which is obtained from the census office is tabulated below.

Table 4: Given population

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Source: from feasibility study, 2007

Table 5: Population growth rate

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Note: population Growth rate from 2030-2045 is found by extrapolation.

Table 6: Population increase

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A. Arithmetic Increase Method

Sample calculation

K= (P2008-P1994) / (2008-1994)

= (33099-16785)/14= 1165.28

Table 7: Calculation of the projected population by arithmetic method

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Sample calculation

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B. Geometric Increase Method

The percentage growth rate (k) for this method is calculated as follows.

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Table 8:Calculation of projected population by geometric method

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Sample calculation

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C. Incremental increase method

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Table 9:Calculation of projected population by incremental increase method

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Sample calculation

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D. Ethiopian statistic authority method

From population growth rates found from CSA, the growth rates of Holeta town is tabulated below.

Table 10: Population growth rate of urban population

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(Source: CSA, 1994 Population and housing census report)

Table 11:Calculation of projected population by Ethiopian census statistics (CSA) method

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Sample calculation

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Table 12:Summary of projected total population by the four methods

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Percentage error calculation

Those the above four formulas Arithmetic increase method, Geometric increase method, Incremental increase method and ESA method percentage error calculated blow in order to select the best fit formula to forecast the future Holeta town population and the town water demand.

Table 13: Percentage error calculation

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Sample calculation

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In general, we can simply observe that Holeta town is the city with vast opportunity of growth as stipulated in the preliminary/feasibility report and documents for the city municipality. In this regard one can select the geometric increase method. On the other, the above percentage error method shows the CSA is more reliable with less error. So we can finally take the CSA method for Holeta future population forecasting .

Table 14:Summary of population projection for Holeta Water supply project

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5. WATER DEMAND ASSESSMENT

5.1 General

Design of water systems require estimation of expected water demands applicable to size the pumping equipment, transmission and distribution pipe lines and storage facilities. Estimating water demands for a particular town depends on the size of the population to be served, their standard of living and activities, the cost of water supplied, the availability of wastewater service and the purpose of demand. It varies according to the requirement of the domestic population, institutional, industrial and social establishments, etc. In addition to these, demand allowances need to be included for leakage, wastage, and operational requirements such as flushing of mains.

5.2 Water demand

Some of the factors that affect water demand are:-

Climatic condition size of the town, culture of people industries cost of wale, fault of water pressure in the distribution system, system of supply etc.

1. Climatic condition: - Water consumption during summer is more than winter. During summer everybody taxes both twice and thrice, clothes also become dirties, more water is used for drinking and more water s consumed, in running coolest. This is why we say water consumption is much more in summer than in winter.

2. Size of the town: - Generally, the demand of water per head will be more on big city than that in small city. In big cities lot of water is required for maintaining clean and health environments while in small towns more or less small.

3. Culture of people: - High class community uses more water due to their better standard of living and high economic status. Middle class people uses water at average rate and for poor people a single water tap may be sufficient for several families.

4. Industries: - more water is used in highly industrial city

5. Cost of water: - If cost of water is high, the water demand will be less .Hence the rate at which water is supplied to consumer may affect the rate of demand.

6. Quality of water: - A water work system having good facility and portable water supply will be more popular with consumers.

7. Pressure in the distribution system: - There would be of great importance in the case of localities having number of two or three storied buildings. Adequate pressure would mean an uninterrupted and constant supply of water.

8. System of supply: - The system of water may be continuous or intermittent. In continuous system water is supplied all 24 hours .while in the case of intermittent system water is supplied for hours of the day only results in some reduction in the consumption. This may be due to decrease in loss and other waste of full use.

9. Method of charging: - In a town where meters are used less quantity of water will be used than in towns without meters in their system. A metered supply ensures minimum of waste as the consumer then know that he was to pay.

Accordingly, the water demand of town is calculated with due consideration of actual conditions of the town and pertinent to available data. Where gaps are observed in acquiring of data, estimates are made from general experiences of the country utilised for similar towns.

The demand of water is divided under the following categories or types of water demand.

- Domestic water demand
- Non domestic demand
- Unaccounted for water

5.3 Domestic Water Demand

The water demand for actual household activity is known as domestic water demand. It includes water for drinking, cooking, bathing, washing flushing, toilet, etc. The demand will depend on many factors, the most important of which are economic, social and climatic.

Based on the available data obtained from the Holeta Water Supply Service has four major modes of service were identified for domestic water consumers. These are:

- House connections (HTC or HTU)
- Yard connections - private (YTO or YTU)
- Yard connections -shared (YTS), and
- Public taps (PT or PTU)

5.3.1 Population Distribution by Mode of Service

The percentage of population to be served by each mode of service for Holeta town is shown in the table below. Due to data limitation we adopt the calculation of extrapolation to know population percentage distribution of the remaining years. The percentage of population to be served by each mode of service will vary with time. The variation is caused by changes in living standards, improvement of the service level, changes in building standards and capacity of the water supply service to expand.

Therefore, the present and projected percentage of population served by each demand category is estimated by taking the above stated conditions and by assuming that the percentage for the house and yard tap users will increase gradually during the project service period while the percentage of tap users will dramatically reduce as more and more people will have private connections as the living standard of people and the socio-economic development stage come up.

This projection envisaged provision of the traditional source users with public taps, and yard connections (own & shared). Further decreases in public tap users are expected on the assumption that more and more people will have private yard connections. Due to this an increase in percentage of yard connections and house connections is anticipated by the end of the design period.

In determining the future trends of the modes of service, factors that influence the growth rates were taken into account, these included:

- Willingness to pay and level of affordability of the community in relation to existing and planned water tariff levels;
- Ability to provide sufficient quantity and quality of water;

Table 15: Population percentage distributions by mode of service.

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Source: ministry of water and energy water supply module for urban, 2003

5.3.2 Per capita Water Demand

The per capita water demand for various demand categories varies depending on the size of the town, the level of development , the type of water supply schemes, the socio- economic conditions of the town, cost of water, system of sanitation and climatic condition of the area. The per capita water demand for adequate supply level has to be determined based on basic human water requirements for various activities of demand category. In Holeta water supply project we used projected per capita demand as follow.

Table 16: Projected per capita demand by mode of service (l/cap/day) (2015-2041)

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Source: ministry of water and energy water supply module for urban, 2003

5.3.3 Domestic Water Demand Projection

In projecting the domestic water demand of Holeta the following procedures were followed:

- Determining population percentage distribution by mode of service and its future projection

- Establishment of per capita water demand by purpose for each mode of service;
- Projected consumption by mode of service;
- Adjustment for climate;
- Adjustment due to socio-economic conditions

- Adjustment for climate

Climate condition is the main factor that affects water demand of the population under consideration. Therefore, the water demand should be adjust for climatic condition .

Table 17: Adjustment factors for climate

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Source: ministry of water and energy water supply module for urban, 2003

Holeta with a mean annual precipitation of 1367 mm belongs to Group C as per the design criteria. Thus, an adjustment factor of 0.9 was taken

- Socio-economic adjustment factors

The socio economic adjustment factor is determined based on the degree of the development of the particular town under study as the socio economic conditions play great role on the amount of water consumption. The determination of the degree of the existing devolvement and future potential of the towns depend on personal judgment due to difficult condition in quantifying many aspects of the development.

Table 18: Adjustment factor for socio-economic conditions

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Source: ministry of water and energy water supply module for urban, 2003

Holeta is classified as a town of “Towns under normal Ethiopian conditions” and, therefore, categorized as a Group C town and was given an adjustment factor of 1.0.

After considering changes in population and changes in the mode of service, per-capita demand and applying the adjustment factors, the domestic demands were calculated and are presented in table below.

Table 19: Projected domestic water demand

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5.4 Non domestic water demand

Non-domestic water demand was also determined systematically. It can be broadly classified into the following major categories:

- Institutional water demand
- Industrial water demand.
- Commercial water demand

[...]

Excerpt out of 154 pages

Details

Title
Water Supply Distribution System Design
Subtitle
In Holeta Town Wolmera Woreda West (Shewa Zone of Oromia region, Ethiopia)
College
Arba Minch University
Course
water supply and environmetal engineering
Grade
1
Authors
Year
2018
Pages
154
Catalog Number
V414284
ISBN (eBook)
9783668651753
ISBN (Book)
9783668651760
File size
1554 KB
Language
English
Notes
The authors of this text are not native English speakers. Please excuse any grammatical errors and other inconsistencies.
Tags
water, supply, distribution, system, design, holeta, town, wolmera, woreda, west, shewa, zone, oromia, ethiopia
Quote paper
Temesgen Mekuriaw (Author)Yohannis Kifle (Author)Yonas Assefa (Author), 2018, Water Supply Distribution System Design, Munich, GRIN Verlag, https://www.grin.com/document/414284

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