AND REDUCTION METHODS IN TURKEY
İzzet ÖZTÜRK Vedat UYAK Mehmet ÇAKMAKCI
Lütfi AKÇA
İstanbul Technical University, Faculty of Civil Engineering, Department of Environmental Engineering 34469,
Maslak – İstanbul, [email protected]
ABSTRACT
Current statistical surveys indicated that approximately 50% of the treated drinking water in city centers is loss and unaccounted in Turkey. On an average, 30% of treated water is lost within distribution systems and storage tanks leakages. Unac-counted usage of water is about 20%, and, however, just only 50% of distributed water is used for residential, industrial and other consumptions. It was reported that total water loss and illegal usages is only less than 30% in limited residential places. On the other hand, average water loss level is about 20% in European Union (EU) Countries, and some countries have water loss levels lower than 10%. This study is aimed to put forward dimensions of water loss and leakage through country on the processes involved in establishing and implementing effective water loss manage-ment strategies with providing national and international experiences. In addition to this, some engineering proposals for effective control of real and apparent losses with general water economy are suggested. Investigation of economic value of extra sources obtained by reducing water loss and leakages is also estimated. Further, in the scope of this search, distribution of water consumption patterns is also presented for metropolitan cities of Turkey.
246 INTERNATIONAL CONGRESS ON RIVER BASIN MANAGEMENT 1. INTRODUCTION
The reduction and control of water loss is becoming even more vital in this age of increasing demand and changing weather patterns that bring droughts to a con-siderable number of locations in the world. Many water utilities have been develop-ing new strategies to reduce losses to an economic and acceptable level in order to preserve valuable water resources. In an urban society, water is supplied by a public or a municipal water system, and this is usually the best assurance of an uninter-rupted supply of economical and safe water to our people in cities [Tooms and Pil-cher, 2006].
The components of water demand are residential, commercial, industrial, insti-tutional or public water uses, and unaccounted system losses and leakages. While all components generate revenue to the utility, the unaccounted system loss and leak-ages are not associated with total cost revenues, and are a source of wasted produc-tion costs. With today’s high water producproduc-tion costs and rates, the expense of detect-ing and mitigatdetect-ing the unaccounted for water and leakages is an attractive option for minimizing operating expenditures. The water utility benefits by (a) saving the pro-duction costs of the water, (b) increasing revenues through sales of water saved, (c) deferring the system expansion and capital expenditures through the capture of lost water, and (d) reducing increases in utility rates, and thus maintaining better con-sumer relations. The annual volume of water loss is an important indicator of water distribution system efficiency, both individual years and as a trend over a period of years. High and increasing water losses are an indicator of ineffective planning and construction, and of low operational and maintenance activities. In Turkish cities, the average yearly water loss is as high as 51% of the water volume produced based on Turkish Statistical Institute (TSI) data of year of 2003 [TSI, 2003].
This study was aimed to propose an effective water loss management in Turkish cities. Thus, IWA water loss approach was advised for present study to manage wa-ter loss problem in Turkey. In the study, in addition to technical loss, some engineer-ing proposals for the effective control of nontechnical loss and general water econ-omy were suggested. Further, investigation of economical values of extra source obtained by reducing water loss was also evaluated. Finally, distributions of water consuming patterns of metropolitan cities in Turkey were as also presented.
2. DIMENSIONS OF WATER LOSS IN DISTRIBUTION NETWORKS
A safe, reliable and efficient water supply system is essential to any community. In a water supply system including the water supply works, treatment plant, distri-bution network and storage facilities, the most expensive component is the water
distribution network [Kleiner, 1997]. In Turkey, there are 81 provinces, and their population is varied between 17,274 and 8,803,468 based on population census of 2000 year. Every province excluding metropolitan cities takes its budget from Pro-vincial Bank per capita basis. In this study, the provinces are divided into three sub-categories according to the center population. First category includes 12 provinces with populations (P) more than 500,000 people. Second category includes 34 prov-inces that populations are varied between 100,000 and 500,000 person, and finally third category consists of 35 provinces which populations are less than 100,000. For this study, the amount and rate of provincial water loss data of the year of 2003 were taken from TSI [TSI, 2003]. According to the water statistics of TSI 2003, water loss and rate of three subcategories are summarized in Figure 1, 2, and 3, respectively.
As shown in these figures, the highest amount of water loss was obtained for
Ankara with 283,102,040 m3/year and the highest percentage of water loss was
re-ported to Kars city with 80%. Total water loss amount for all provincial centers were
1,508,901,825 m3/year and the average water loss rate was found to be 51% in Turkish
cities for year of 2003. Variation of water loss in terms of annual amounts and per-centages with population classes of city centers are given in Figure 4. On the other hand, as summarized in Figure 4, the highest water loss amount was observed for provinces which populations are varied between 100,000 and 500, 000 people.
2.1. WATER DISTRIBUTION PATTERNS
A water distribution pattern for this study is divided into five groups. These consumers are (1) governmental institutions, (2) commerce and industry sectors, (3) residential buildings, (4) construction sectors and (5) parks, gardens, public fountain and etc. Water distribution rate among these consumers for the year of 2003 are seen in Figure 5. As seen in this figure, 65-72 % of distributed water was used at residen-tial buildings. Institutional water consumption was very high for especially low populated cities (P < 100,000).
2.2. MAJOR FACTORS CONTRIBUTING TO HIGH LEVELS OF WATER LOSS IN TURKEY
There are several reasons for the high level of water loss in Turkey. These factors are given below, and some advisory solutions were briefly proposed in next sections.
248 INTERNATIONAL CONGRESS ON RIVER BASIN MANAGEMENT
2.2.1. Age of pipe network
It is estimated that nearly more than 50% of the pipe network was laid over 50 years ago. These include cast iron, asbestos cement, galvanized and carbon steel pipes. All these materials suffer from degradation over time due to operational measures, environmental conditions and general wear and tear and result in in-creased leakage in the network. It is therefore necessary to replace older mains so that less leakage occurs.
2.2.2. Poor maintenance of networks
In some cities including Istanbul, Ankara, Kayseri, etc., water authorities has performed a maintenance program for distribution system, and in recent years ap-proximately more 50% of network system was replaced. For all cities, it is so difficult to find financial support to renew the water distribution system. Thus, the lack of finance to buy proper materials and poor construction resulted in increased leakage in the system.
2.2.3. Water scheduling
The problem of water scheduling caused by an intermittent supply results in leakage, with a cyclic pressure situation created due to having the supply turned on and off, increased levels of leakage are experienced due to stress being inflicted on the pipes causing them to rupture. There is clear irony in this situation as the prob-lem of water scheduling is caused by water shortages. Due to high levels of water loss, a continuous supply is not available resulting in water schedules. The elimina-tion of water schedules then, is a desired goal.
2.2.4. Customer side leakage
Because of the nature of the water storage systems in the country and the gener-ally low rates paid by customers, there is little incentive to conserve water. Conse-quently, storage tanks and fittings remain unrepaired for long periods thereby con-tributing to significant loss. It is a significant component of water loss and a strain on the delivery of water.
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Figure 1. Water loss amounts and rates of metropolitan city centers (P> 500,000)
2.2.5. Illegal connections
There are a significant number of illegal users of water within distribution sys-tem in Turkish cities. The number of households who do not pay water rates but receive water from its distribution system is not known. As a consequence, they contribute significantly to apparent losses and revenue loss to the water authority. These connections are often poorly laid just a few inches below the surface and will break easily resulting in real losses taking placed in the form of leakage. Illegal con-nections are therefore of significant concern of water utilities.
3. WATER LOSS MANAGEMENT
This work represents a major step to define the best practice approach for assess-ing and presentassess-ing basic elements of water loss management program in Turkish cities, and it will focus on international water loss approach to promote and facilitate the application of IWA recommended methodology of leakage monitoring and pres-sure management system.
0 10 20 30 40 Esk i ş ehir Ma laty a Erz uru m Sak ary a De niz li Siv as Bal ı ke sir Ma nis a Ad ı ya ma n Kü tah ya Isp art a Ay d ı n Ak sar ay Ed irn e Ord u Erz in can Zo ng uld ak
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Figure 4. Total water loss amounts and average water loss rates of city centers
3.1. LEAKAGE MONITORING AND CONTROL
Leakage management can be classified into two groups including passive leak-age control and active leakleak-age control. Passive control is reacting to reported bursts or a drop in pressure, usually reported by customers or noted by the company’s own staff while carrying out duties other than leak detection. This method can be justified in areas with plentiful or low cost supplies. Often practiced in less developed supply system where the occurrence of underground leakage is less understood, it is the first step to improvement. Active leakage control (ALC) is when company staff is de-ployed to find leaks which have not been reported by customers or other means.
The main ALC methods are regular survey and leakage monitoring. Regular survey is a method of starting at one end of the distribution networks and proceed-ing to the other usproceed-ing one of the followproceed-ing techniques:
♦ listening for leaks on pipe-work and fittings
♦ reading metered flows into temporarily-zoned areas to identify high-volume
night flows
♦ using clusters of noise loggers (leak localizing)
Leakage monitoring is flow monitoring into zones to measure leakage and to prioritize leak detection activities. This has now become one of the most cost effective activities for leakage management programs.
The most appropriate leakage control policy will mainly be dictated by the char-acteristics of the network and local conditions, which may include financial con-straints on equipment and other resources. Staffing resources are relevant, as a labor intensive methodology may be suitable if manpower is plentiful and cheap. If the geology of the area allows a high proportion of leaks to appear at the surface, a
pol-252 INTERNATIONAL CONGRESS ON RIVER BASIN MANAGEMENT
icy of regular survey followed by rapid repair may be adequate. If some leaks fail to appear at the surface, then, a more intensive policy of leakage monitoring is required.
The main factor governing choice, however, is the value of the water, which de-termines whether a particular methodology is economic for the savings achieved. A low activity method, such as repair of visible leaks only, may be cost-effective in supply areas where water is plentiful and cheap to produce. On the other hand, countries which have a high cost of production and supply, like the Golf States, can justify a much higher level of activity, like continual flow monitoring, or even te-lemetry systems, to warn of a burst or leakage occurring [Farley and Trow, 2003].
3.2. LEAKAGE MONITORING WITH DISTRICT METER AREA (DMA)
A flow measuring system in a water distribution system should include not only measurement of total flows from source or treatment plants, but also zone and dis-trict flows. This allows the engineer to understand and operate the distribution sys-tem in smaller areas, and allows more precise demand prediction, leakage manage-ment and control to take place. The measuremanage-ment system must therefore be hierar-chical at a number of levels, beginning at production measurement, via zone and district measurement and ending at the customer’s meter.
The technique of leakage monitoring is considered to be the major contributor to cost-effective and efficient leakage management. It is a methodology which can be applied to all distribution networks. Even in systems with supply deficiencies leak-age monitoring zones can be introduced gradually. One zone at a time is created and leaks detected and repaired, before moving on to create the next zone. This system-atic approach gradually improves the hydraulic characteristics of the network and improves supply.
Leakage monitoring requires the installation of flow meters at strategic points throughout the distribution system, each meter recording flows into a discrete dis-trict which has a defined and permanent boundary. Such a disdis-trict is called a disdis-trict meter area and the concept of design and operation of DMA has been detailed in elsewhere [Farley and Trow, 2003].
The design of a leakage monitoring system has two aims:
1. To divide the distribution network into a number of zones or DMAs,
each with a defined and permanent boundary, so that night flows into each district can be regularly monitored, enabling the presence of unre-ported bursts and leakage to be identified and located.
2. To manage pressure in each district or group of districts so that the
It therefore follows that a leakage monitoring system will comprise a number of districts where flow is measured by permanently installed flow meters. In some cases the flow meter installation will incorporate a pressure reducing valve.
3.3. PRESSURE MANAGEMENT THROUGH DISTRIBUTION SYSTEM Pressure management can be defined as the practice to manage system pressures to an optimum level of service ensuring sufficient and efficient supply to legal uses and consumers, while eliminating or reducing pressure transients and variations, faulty level controls and reducing unnecessary pressures, all of which cause the dis-tribution system to leak and break unnecessarily. There are many different tools that can be used when implementing pressure management, including pump controls, altitude controls and sustaining valves [Lambert et al., 2006].
It was reported that many water utilities introduced pressure management to their water distribution systems. In the most cases, large reductions in a new break frequency can be achieved over a wide range of pressures. In Australia, Canada, and Italy, ongoing monitoring shows that the reductions in break frequency have been sustained for over five years to date by implementing pressure management proce-dure [Lamber et al., 2006]. On the other hand, the rapid reduction in new break fre-quency following pressure management is immediately evident for Gracanica in Bosnia and Herzegovina.
Some of the pressure management benefits reported by many different utilities include:
♦ Reduction in annual repair costs
♦ Reduction of the repair backlog, shorter run times for bursts
♦ Fewer emergency repairs, more planned work
♦ Reduced inconvenience to customers
Calculations of the economic benefit of pressure management have been based on the predicted reduction in flow rates of existing leaks and the value of the water thus saved. If management of excess pressure can also regularly achieve reductions in numbers of breaks of between 28% and 80% per year, the annual savings in repair costs will usually be far greater than the value of the water saved.
Replacement of mains and services, the most expensive aspect of water distribu-tion system management, is normally initiated by break frequencies that are consid-ered to be excessive. Most water utilities consider break frequency to be a factor outside their control, and something that can only be remedied by expensive re-placement of mains and services. However, if pressure management can reduce break frequencies and extend the working life of parts of the distribution infrastruc-ture by even a few years, the economic benefits would generally be even greater than the short term reduction in repair costs.
254 INTERNATIONAL CONGRESS ON RIVER BASIN MANAGEMENT 4. ECONOMICAL DIMENSION OF WATER LOSS
As shown in Figure 1, 2, and 3, water loss rate was varied between 28 and 80%. If it is assumed that unit water production cost is half price of selling, total cost of water loss for all Turkish cities will be 563,906,549 YTL (304,800 EURO) for 2003 year provided that water loss rate is reduced to 20%. Average water selling price is ob-tained from TSI [TSI, 2003]. Figure 6 shows the relationships between the rate of reducing water loss and cost saving. Besides, in the case of reducing the rate of water loss to 20% through provincial centers in Turkey, water utilities will have a gain of 1,691,719,647 YTL (914,400 EURO) for the year of 2003 (Figure 6).
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Figure 5. Water distributions patterns of provincial centers
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5. CONCLUSION AND RECOMMENDATION
This study presented the current water loss perspectives of Turkish cities. Fur-ther, its aim was to offer two IWA approach to control water loss and leakages through water distribution networks. Application of these two methods to distribu-tion systems will result in better knowledge of the components of uncontrolled flow rate, the technical losses (real losses) and nontechnical losses (apparent losses) in-cluding demands related to metering errors on the system. For the future, application of these two IWA methods has the potential for reducing water loss within entire of water distribution systems for Turkish cities.
This paper has attempted to put forward the current situation of water loss in Turkey. Besides, it proposes appropriate solutions for the reduction and control of water loss. It is hoped that it will be a catalyst for increased and enhanced awareness and implementation of water loss solutions in the country.
6. REFERENCES
Tooms, S., and Pilcher, R. (2006) “Practical Guidelines on Efficient Water Loss Man-agement”, Water Supply, August, 47.
Farley, M., and Trow, s. (2003) “Losses in Water Distribution Networks: A Practitioner’s Guide to Assessment, Monitoring and Control”, IWA Publishing, Alliance House, 12 Caxton St., London, UK.
Statistical Department of Turkey (TUIK), (2003) Statistical Department of Turkey Water Statistics, In Turkish, Unpublished
Kleiner, Y. (1997) “Water Distribution Network Rehabilitation: Selection and Scheduling of Pipe Rehabilitation Alternatives”, PhD Thesis, University of Toronto, Toronto, Canada.
Lambert, A.O., Brown, T.G., Takizawa, M., and Weimer, D. (1999) “A Review of Per-formance Indicators for Real Losses from Water Supply System”, J. Water SRT-Aqua, 48:6, 227-237.
