reliability of hydraulic structures under climate change

RELIABILITY OF HYDRAULIC STRUCTURES UNDER

CLIMATE CHANGE

Kamran EmamiKuritKara Engineers

Tehran, Iran

Kurit Kara Consulting Engineers

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 livewithout 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

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…………


World population from 1000 BC to 2300 BC



Key findings of the Climate change report

75-250 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;





Adaptation Strategies

Predict the Climate Change trends

Non-Structural Approaches

Structural ductility

Public participation and Demand

Management

Holistic, integrated and Creative Approaches

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.


Establish the interdependence and

synergy of structural and non-structural

approaches in design.


Adapt to the stochastic nature of river

flow by integration of seasonal

characteristics and river forecasting.


Design hydraulic structures to adapt to

extreme events far larger than design

parameters and remain inherently safe

(structural ductility)


Enhance safety by 'designing'

emergency and crisis management

preceding the events and in real time for

the structure and downstream population

centers

FAST diagram of Holistic Design

Evolution of Non-Structural Approaches

LIVING WITH FLOODING

Flood risk cannot be eliminated

Residual risk can be managed

• 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

CHARACTERISTICS RESULTSOF THE DEVELOPMENTS

Protection levels are generally far below the economic optimum

0

200

400

600

800

1000

1200

Cost 1950

Damage 1950

Total 1950

Damage 2005

Total 2005

WHY CONSIDER RESIDUAL RISK?

NewOrleansFloodsSeptember2005

WHY CONSIDER RESIDUAL RISK?

New Orleans FloodsSeptember 2005

Challenges of flood Engineers

Substantial Increase of Flood Risk

Uncertainty in all aspects



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



• Avoiding costly irreversible mistakes

•Updating the Objectives



• Resilience

• Harmony with Environment (step by step)

• Passive and Active AM

• Stakeholders Participation

• Enhanced Real time reactions



كارايي

يش بيني پسامانه هاي و هشدار

نفر300000: 1970

نفر140000: 1991

نفر3500: 2007

1970 1991 2007 0

50000

100000

150000

200000

250000

300000

350000

Human Loss

Bangladesh Cyclones

Climate Forecasting by El Nino and La nina

Normal (Dec. 93)

El Nino (Dec. 97)

La Nina (Dec. 98)


Risk Analysis

Flood management in Sistan, Iran

Successes of AM in Early Impoundment of Large dams in Iran

Successes of AM in Early Impoundment of Large dams in Iran

مهندسان مشاوركريت كارآ

VE of Ajichay Spillway

Vanyar Dam Spillway Value

Engineering Workshop - 2003

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

Routing of Floods in Aji Chay Reservoir

PMF10000100050010050Return Period (Year)

29851052753671501431Peak Inflow

2280780575500330260Peak Outflow (Base Case)

1350280180165160160 Peak Outflow

(VE Alternative)

more than twice of 10000 Year

>1000200100127Return Period (Base Case)

30% more than 10000 Year

<104333 Return Period

(VE alternative)

Aij Chay Flood Forecsting and Warning system

Tabriz Weather Radar

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.

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



ب% ا توج%ه ب%ه ع%دم قطعيته%ا بايس%تي بج%اي راه%برد اجتن%ابي از راه%برد س%ازي اس%تفاده نم%ود. در اين راس%تا مق%اوم س%ازي تط%بيقي و مق%اوم

س%دهاي خ%اكي در مقاب%ل س%يالب و اس%تفاده از س%دها و فرازبن%دي بت%ني ميتواند بيشترين ايمني را با حداقل هزينه تامين نمايد.

Free-standing blocks,

so called Fusegates ,

are installed

side by side

across the spillway sill

Downstream toe abutment

Upstream seal

Downstream bucket side

Overspilling crest

Bucket

Side seal

Concrete sill

Inlet well

Adaptability and FlexibilityDescription of a Fusegate

In such a way

that they form

a watertight barrier.

Description of a Fusegate

Working Concept – Normal Operation

Toe abutment

Drain hole

Ballast

Inlet well

Base chamber

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

Working Concept – Exceptional FloodsFor exceptional floods only, the

reservoir level increases until the water begins spilling

over the inlet lips.

Drain holes can not discharge all the flow.

Uplift pressure builds up in the

chamber.

Working Concept – Exceptional Floods

Uplift pressure causes the Fusegate to overturn.

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

0

50000

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150000

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250000

300000

350000

400000

0,0 10,0 20,0 30,0 40,0 50,0 60,0

time (hours)O

utflo

w (c

fs)

Tipping stages

Flood Routing through a Fusegated Spillway

PMF

Blue curve: inflow / Red curve: outflow

Increase Storage Capacity

3. No increase in Maximum Water Level

2. Fusegates are used to increase the Full Supply Level

1. The sill is modified slightly

New Full Supply Level

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%

Terminus Dam, CA – USA

3. The storage capacity of the dam is recovered by installing Fusegates.

2. The spillway sill is lowered in order to pass the design flood.

1. The spillway is not able to pass the design flood below the MWL.

Increase Discharge Capacity

4. The storage capacity could even be increased by installing higher Fusegates.

Full Supply Level

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%

Shongweni Dam – South Africa

1995 Most outstanding Civil Engineering

Achievement in Technical Excellence Award


Dam Safety Strategy in Switzerland


در مورد كاهش ريس%كICOLD بولتنسده%ا بوسيله روشه%اي غي%ر سازه اي


Levees only!

Evolution of Flood Management Strategies

Documents

reliability of hydraulic structures under climate change