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reliability of hydraulic structures under climate change

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Presentation on theme: "reliability of hydraulic structures under climate change"— Presentation transcript:

1 reliability of hydraulic structures under climate change
Kamran Emami KuritKara Engineers Tehran, Iran


3 A summary of UNICEF report on THE STATE OF THE WORLD’S CHILDREN 2005
Number of children in the world: 2.2 billion Number of children living in poverty: 1 billion Number of children in developing countries who live without adequate shelter 640 million Number of children who have no access to safe water: one in five 400 million Number of children who have no access to health services 270 million Number of children who are out of school 121 million Total number of children younger than five living in France, Germany, Greece and Italy: Total number of children worldwide who died in 2003 before they were five 10.6 million Daily toll of children in the world who die before their fifth birthday: 29,158 The number of children who die each day because they lack access to safe drinking water and adequate sanitation: 3,900 Many technical jumps are desperately needed ………… Kurit Kara Consulting Engineers

4 World population from 1000 BC to 2300 BC
Kurit Kara Consulting Engineers

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6 Key findings of the Climate change report
million people across Africa could face water shortages by 2020; More heavy rain events are very likely and more areas are likely to be hit by drought; Crop yields could decrease by up to 30% in Central and South Asia; Agriculture fed by rainfall could drop by 50% in some African countries by 2020; Kurit Kara Consulting Engineers

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11 Adaptation Strategies
Predict the Climate Change trends Non-Structural Approaches Structural ductility Public participation and Demand Management Holistic, integrated and Creative Approaches

12 Holistic Approach to adaptive design of hydraulic structures (Emami, 1997)
Ensure a flexible and adaptive design in view of hydrosystems changes and the inherent uncertainties of water engineering.

13 Holistic Approach to adaptive design of hydraulic structures (Emami, 1997)
Establish the interdependence and synergy of structural and non-structural approaches in design.

14 Holistic Approach to adaptive design of hydraulic structures (Emami, 1997)
Adapt to the stochastic nature of river flow by integration of seasonal characteristics and river forecasting.

15 Holistic Approach to adaptive design of hydraulic structures (Emami, 1997)
Design hydraulic structures to adapt to extreme events far larger than design parameters and remain inherently safe (structural ductility)

16 Holistic Approach to adaptive design of hydraulic structures (Emami, 1997)
Enhance safety by 'designing' emergency and crisis management preceding the events and in real time for the structure and downstream population centers

17 FAST diagram of Holistic Design


19 Evolution of Non-Structural Approaches

20 LIVING WITH FLOODING Flood risk cannot be eliminated
Residual risk can be managed



OF THE DEVELOPMENTS protection levels are generally far below the economic optimum serious risk of loss of a large number of lives when an extreme event would occur costs of only physical solutions are generally unaffordable

24 Protection levels are generally far below the economic optimum

New Orleans Floods September 2005

New Orleans Floods September 2005

27 Challenges of flood Engineers
Substantial Increase of Flood Risk Uncertainty in all aspects

28 Kurit Kara Consulting Engineers

29 Adaptive management Principles (2004)
Adaptability (Change Threat to Opportunity) Flexible Decision Making (uncertainties) Monitoring and vigilance Learning while doing Application of New knowledge and technologies Kurit Kara Consulting Engineers

30 Adaptive management Principles (2004)
Avoiding costly irreversible mistakes Updating the Objectives Kurit Kara Consulting Engineers

31 Adaptive management Principles (2004)
Resilience Harmony with Environment (step by step) Passive and Active AM Stakeholders Participation Enhanced Real time reactions Kurit Kara Consulting Engineers

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Bangladesh Cyclones 1970: نفر كارايي سامانه‌هاي پيش‌بيني و هشدار 1991: نفر 2007: نفر Kurit Kara Consulting Engineers

34 Climate Forecasting by El Nino and La nina
Normal (Dec. 93) El Nino (Dec. 97) La Nina (Dec. 98)

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Risk Analysis Kurit Kara Consulting Engineers

36 Flood management in Sistan, Iran

37 Successes of AM in Early Impoundment of Large dams in Iran

38 Successes of AM in Early Impoundment of Large dams in Iran

39 VE of Ajichay Spillway مهندسان مشاوركريت كارآ

40 Vanyar Dam Spillway Value Engineering Workshop - 2003

41 VE Proposals and Results
Enhanced Reservoir Operation Based on new rule curve, Seasonal forecasting and flood Warning Reduced Cost (spillway length form 110 to 40m) Enhanced Dam Safety Drastic Attenuation of floods in the reservoir

42 Routing of Floods in Aji Chay Reservoir

43 Aij Chay Flood Forecsting and Warning system

44 Tabriz Weather Radar

45 Conclusions Based on experiences of application of AM in several larges projects it can be concluded that: Adaptive flood risk Management is an effective, efficient and versatile tool. AM emphasize of Non-structural approaches enhance adaptability, flexibility and sustainability.

46 Basic Requirements: Efficient and reliable Water Managers and experts
Comprehensive and reliable Monitoring System Preparedness and Plans for Emergencies Regulations to ensure flexibility and adaptability Resources and Training

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با توجه به عدم قطعيتها بايستي بجاي راهبرد اجتنابي از راهبرد تطبيقي و مقاوم سازي استفاده نمود. در اين راستا مقاوم سازي سدهاي خاكي در مقابل سيلاب و استفاده از سدها و فرازبندي بتني ميتواند بيشترين ايمني را با حداقل هزينه تامين نمايد. Kurit Kara Consulting Engineers

49 Adaptability and Flexibility Description of a Fusegate
Free-standing blocks, so called Fusegates, are installed side by side across the spillway sill SLIDE 3 – DESCRIPTION FG (1/2) A Fusegate unit is formed by 3 parts: the base, the bucket and the well. Downstream toe abutments prevent Fusegates from sliding, and seals avoid leakage from the reservoir.

50 Description of a Fusegate
In such a way that they form a watertight barrier. SLIDE 4 – DESCRIPTION (2/2) Fusegates are installed side by side on the spillway sill to form a watertight barrier. When water is below Fusegates’ crest, the Fusegates act just like a dam.

51 Working Concept – Normal Operation
Common Floods are discharged between the Fusegates crest and the inlet levels Inlet wells are set at different elevations At this stage the chamber is empty Toe abutment Drain hole Ballast Inlet well Base chamber SLIDE 5 – NORMAL OPERATION In normal operating conditions, moderate floods spill over the Fusegate crest. Note that inlet wells are set at different elevations.

52 Working Concept – Exceptional Floods
For exceptional floods only, the reservoir level increases until the water begins spilling over the inlet lips. SLIDE 6 – EXCEPTIONAL FLOODS (1/2) For exceptional floods only, the water spills over the Fusegates and into the well; the drain hole cannot discharge the extra water and uplift pressure increases. Uplift pressure builds up in the chamber. Drain holes can not discharge all the flow.

53 Working Concept – Exceptional Floods
Uplift pressure causes the Fusegate to overturn. SLIDE 7 – EXCEPTIONAL FLOODS (2/2) The uplift pressure, combined with hydrostatic pressure, is sufficient to overcome the restraining forces and causes the rotation of the unit off the spillway. The Fusegate is then washed away from the sill. If the water level continues to rise after the first breach, more Fusegates will rotate, according to their well level, which is set to a pre-determined water level. Eventually, no more unit may remain on the sill and the spillway is free to pass the original maximum design flood.

54 Environmental Impacts
Progressive release of the flood water Outflow not exceeding the inflow Tip off probability = very low (usually 1 in 100 years and above) Maximum Water Level in the reservoir not raised General principles Tipping stages Flood Routing through a Fusegated Spillway PMF Blue curve: inflow / Red curve: outflow SLIDE 10 – ENVIRONMENTAL IMPACTS Fusegates are engineered in such a way that negative impacts of the spillway rehabilitation on river regimes and reservoir elevations are mitigated. The Fusegate solution ensures that there will be no sudden increase in the outflow and that the MWL will never be raised, which is very important for the downstream population. The diagram shows the flood routing hydrograph of a fusegated spillway which has the same degree of reliability as an ungated spillway.

55 Increase Storage Capacity
1. The sill is modified slightly 2. Fusegates are used to increase the Full Supply Level 3. No increase in Maximum Water Level New Full Supply Level SLIDE 11 – APPLICATION - Increase Storage Capacity The Fusegate System has a wide range of applications. One of them is to increase the dam storage capacity. First, the sill is modified slightly. Then, we install Fusegates to increase the Full Supply Level without increasing the MWL.

56 Terminus Dam, CA – USA Main characteristics Purpose: Flood attenuation
Discharge capacity: 8500 m3/s Spillway length: 93 m Fusegate height: 6,50 m Number of units: 6 Former storage capacity: 173 Mm3 New storage capacity: 226 Mm3 Storage increase: 30% SLIDE 12 – TERMINUS A good example of this type of application is the Terminus Dam in California, owned by the US Corps of Engineers. By using Fusegates for the auxiliary spillway enlargement, the existing storage has been increased by more than 50 Mm3/s. The Fusegate alternative provided 6M dollars of savings on the project. Without the Fusegate option, the project would not have been realized.

57 Increase Discharge Capacity
1. The spillway is not able to pass the design flood below the MWL. 2. The spillway sill is lowered in order to pass the design flood. 3. The storage capacity of the dam is recovered by installing Fusegates. 4. The storage capacity could even be increased by installing higher Fusegates. Full Supply Level SLIDE 14 – APPLICATION – Increase Discharge Capacity Another range of application is to increase the discharge capacity of an undersized spillway without lowering the Normal Water Level, in other words, without sacrificing the water storage. The WML is again unchanged. Moreover, it is possible to increase the storage capacity of a dam while rehabilitating its undersized spillway.

58 Shongweni Dam – South Africa
Main characteristics Purpose: Recreation Storage capacity: 6,6 Mm3 Spillway length: 125,0 m Fusegate height: 6,5 m Number of units: 10 Former discharge capacity: 1245 m3/s New discharge capacity: 5000 m3/s Discharge capacity increase: 300% SLIDE 15 – SHONGWENI DAM At Shongweni, the original design flood was approximately 1250 m3/s and has been increased to 5000 m3/s with Fusegates to fulfill safety requirements. 1995 Most outstanding Civil Engineering Achievement in Technical Excellence Award

59 Dam Safety Strategy in Switzerland
Kurit Kara Consulting Engineers

60 Kurit Kara Consulting Engineers
بولتن ICOLD در مورد كاهش ريسـك سدهـا بوسيله روشهـاي غيـر سازه‌اي Kurit Kara Consulting Engineers

61 Kurit Kara Consulting Engineers
Levees only! Kurit Kara Consulting Engineers


63 Evolution of Flood Management Strategies

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