Analysis of Istanbul Water Supply System

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• Analysis of Istanbul Water Supply System
• Operation Policies
• Bihrat ÖNÖZ
• Beyhan YEGEN
• Yigit UÇAR
• Istanbul Technical University

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• Istanbul City situated on 2 continents
• Europe Asia on both sides of Bosphorous.
• Naturally, the water supply system and dams are
  on both sides of the city and water transmission
  from Asia to Europe is possible by a sub water
  passage.

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• Optimization of reservoir operation is important
  during,
• Planning, Design, Construction phases.
• The operation rule in real time
• for a long duration is determined by optimization
  with mean incoming flows
• for a short duration is determined by estimation
  of the future incoming flows.

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• Reservoir operation rule may be obtained to
  establish a balance within time, between purposes
  and between reservoirs.
• In this study, operation policies are to be
  analysed by achieving a balance within time using
  past flow data and targets.
• Firstly standard operation policy,
• Secondly hedging policy will be used.

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• if Xt St lt Tt ? Yt Xt
  St
• if Tt lt Xt St lt Tt C ? Yt Tt
• if Tt C lt Xt St ? Yt Xt
  St C
• sop simple and in many cases gives good results
  BUT
• in dry periods when sufficient water is not
  present, the usage of all water is of subject
  giving way to reservoir being completely emptied.
  

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• HEDGING POLICY
• The extent at which a storage basin meets the
  demand is measured by performance indices.
• sop maximizes reliability and resiliency
  BUT
• great deficiencies may emerge!
• As a tool for decreasing deficiencies hedging
  policy may be used. That is to say that some
  portion of the water is saved for future use in
  periods when water is scarce.
• Hedging decreases reliability and resiliency
  by a quantity, decreases mean and especially the
  variance of max. deficiency as well.

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• DRY PERIOD
• Since max. deficiencies are closely related to
  dry period, analysis of dry period was
  inevitable.
• This analysis was performed as a runs analysis.
• Considering the weight of Ömerli Dam within the
  system, dry period was determined as 1988-1994.
• However operation records of ISKI were only
  available for 1989-2004 causing the dry period to
  be 1989-1994.
• BUT on analysis of European side water amounts
  given to the city it was noticed that effects of
  dry period continued in years 1995 and 1996 so
  the dry period was decided to be taken as
  1989-1996.

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• TARGET VALUES
• By examining the amounts of water ISKI gave to
  the city, monthly water targets to be given to
  the city have been determined separately for the
  two sides.
• To find the monthly target value, the mean of
  yield/month have been taken excluding the values
  belonging to 1989-1996 years.

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• Investigation of ISKI operation policy

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• European side
• For analysing ISKIs operation policy closely,
• Xt St vs Yt graphs have been obtained for the
• sum of Alibeyköy-Terkos reservoirs,
• for the dry years and non-dry years.
• Less water is given to the city during dry years
  with respect to non-dry years. This gives way to
  deficiencies.
• Asian side
• Ömerli reservoir, similar results.

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ISKI operation, yield vs available water
diagram for month July (European side)
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• ISKI operation,yield vs available water for month
  June (Asian side)

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• Operation of system by standard operation policy

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• Operation of system by hedging policy

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• A stepwise (2 steps) hedging has been performed.
• The limit values of the steps have been
  determined by trial and error.
• Emergence of deficiencies also continued.

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• Standard operation and hedging policies, yield vs
  available water diagram for month September
  (European side)

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• Standard operation and hedging policies, yield vs
  available water diagram for month September
  (Asian side)

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• Results
• Dry period of the system has been accepted as
  1988-1994.
• The monthly target values for non-dry years have
  been determined.
• ISKI operation has been investigated. It is
  possible to deduce that ISKI follows a certain
  policy.
• European side
• Comparison of ISKI to so and ho
• Especially during summer months so deficiencies
  increase significantly,for all months ho
  deficiencies decrease significantly with respect
  to ISKI. Insufficient reliability of data.
• Asian side
• Similar results, but the betterment of ho is no
  too much.

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• Thank you for your attention