Cyclone impacts on engineering design

standards for Infrastructure

(case study: Sultanate of Oman)

Presented by:

Prof. Dr. Alaa El-Zawahry*

* Professor of Hydraulics, Irrigation & Hydraulics Dept., Faculty of Engineering, Cairo Univ. Email:ceeg@link.net

The 4th Workshop on Tropical Cyclones and Flash Floods )Evaluation of the Sultanate's Experience and Lessons Learned after Guno and Phet Cyclones)”

OUTLINE Introduction

Generation Mechanism of Cyclones

Cyclones Naming

Categories of Tropical Cyclones

Cyclones History in Oman

Gonu, Phet, and Mikono Cyclones

Meteorological Model

Ground Stations

Damage of Gonu and Impacts on Design Criteria

Risk Management

Generation Mechanism of Cyclones

What are the Necessary Conditions for the Formation of the Tropical Cyclones?

» Low-level relative Vorticity (ζr)

» Coriolis parameter (ƒ)

» Low vertical shear

» Sea surface temperatures

» Vertical gradient of effective potential temperature (θe)

» Middle troposphere relative humidity (RH)

Generation Mechanism of Cyclones

Convective Towers

Cyclones Naming Importance for naming tropical cyclones

It would help identify each individual tropical cyclone

Local and international media become focused to the tropical cyclone

It does not confuse the public when there is more than one tropical cyclone in the same area

The name of the tropical cyclone is well remembered by million of people as it is unforgettable event shoes name will long be remembered

Warnings reach a much wider audience very rapidly

Cyclones Naming Naming of tropical cyclones over north Indian

Ocean

The Panel member’s name are listed alphabetically country wise

The name will be used sequentially column wise

The first name will start from the first row of column one and continue sequentially to the last row in column eight. Example, this will be as Onil, Hibaru, Pyar, Baaz …………. Amphan

The names which have been already used from the list are highlighted

Cyclones Naming

Panel Member

Column One Column Two Column Three Column Four

Name Pron’ Name Pron’ Name Pron’ Name Pron’

Bangladesh Onil Onil Ogni Og-ni Nisha Ni-sha Giri Gi-ri

India Agni Ag’ni Akash Aakaa’sh Bijli Bij’li Jal Jal

Maldives Hibaru --- Gonu --- Aila --- Keila ---

Myanmar Pyarr Pyarr Yemyin Ye-myin Phyan Phyan Thane Thane

Oman Baaz Ba-az Sidr Sidr’ Ward War’d Murjan Mur’jaan

Pakistan Fanoos Fanoos Nargis Nar gis Laila Lai la Nilam Ni lam

Sri Lanka Mala --- Rashmi Rash’mi Bandu --- Mahasen ---

Thailand Mukda Muuk-dar Khai Muk Ki-muuk Phet Pet Phailin Pi-lin

Cyclones Naming

Panel Member

Column Five Column Six Column Seven Column Eight

Name Pron’ Name Pron’ Name Pron’ Name Pron’

Bangladesh Helen Helen Chapala Cho-po-la Ockhi Ok-khi Fani Foni

India Lehar Le’har Megh Me’gh Sagar Saa’gar Vayu Vaa’yu

Maldives Madi --- Roanu --- Mekunu --- Hikaa ---

Myanmar Nanauk Na-nauk Kyant Kyant Daye Da-ye Kyarr Kyarr

Oman Hudhud Hud’hud Nada N’nada Luban L’luban Maha M’maha

Pakistan Nilofar Ni lofar Vardah Var dah Titli Titli Bulbul Bul bul

Sri Lanka Priya --- Asiri Aa’siri Gigum Gi’gum Soba ---

Thailand Komen Goh-men Mora Moh-rar Phethai Pay-ti Amphan Um-pun

Categories of Tropical Cyclones

Tropical Cyclone Intensity Scale

Category Wind Speed

Super Cyclonic Storm > 222 km/h

Very Severe Cyclonic Storm 118 – 221 km/h

Severe Cyclonic Storm 88 – 117 km/h

Cyclonic Storm 62 – 87 km/h

Deep Depression 52 – 61 km/h

Depression ≤ 51 km/h

Storms affecting the Arabian Peninsula by month

Month Number of storms

May

14

June

18

July 3

August 1

September 3

October 7

November 8

December 5

Storms affecting the Arabian Peninsula by period

Period Number of storms

1800s 5

1900–49

10

1950s 3

1960s 6

1970s

11

1980s 2

1990s 6

2000s 5

2010s

11

Gonu Cyclone (June 2007)

Weather Research and Forecasting Model

Wind Speed (kts) Forecasted (June 1, 2007) Dis = 5 km Do3

a) 00:00UTC

b) 06:00UTC

c) 12:00UTC

d) 18:00UTC

Gonu Cyclone (June 2007)

Weather Research and Forecasting Model

Wind Speed (kts) Forecasted (June 7, 2007) Dis = 5 km Do3

a) 00:00UTC

b) 06:00UTC

c) 12:00UTC

d) 18:00UTC

Gonu Cyclone (June 2007)

Weather Research and Forecasting Model

Lat:19.2N Lon:64.9E

Lat:18.7N Lon:66.0E

METEOSAT-7 RGB = CH (1,4)

Gonu Cyclone (June 2007)

Weather Research and Forecasting Model

Lat:23.9N Lon:59.4E Lat:23.0N

Lon:60.4E

Gonu Cyclone (June 2007)

Weather Research and Forecasting Model

Results and Discussion

Weather Research and Forecasting Model

Parameter SI WRF-ARW Range of Error

Win

d S

pee

d (

inte

nsi

ty)

June 1 D (in late the day) D (in late the day) Generally, in the model

forecast period, the intensity

of the tropical cyclone was

relatively weaker than the

observed.

The system attained peak

winds SuCS late on June 4,

While the model attained

peak winds VSCS early on

June 6.

June 2 DD – CS (Along the day) D – DD (Along the day)

June 3 SCS - VSCS

Along the day

Within 3 and 4 June the model

upgraded the system gradually

until reached SCS. June 4

SuCS – VSCS

In late the day

June 5,

6

The system stills VSCS

until early on June 6, and

the system downgraded

to SCS until late on

June 6.

The model upgraded the system

gradually until reached VSCS in

early on June 6, and the

system downgraded gradually.

June 7

The system downgraded to

CS until weakened at the

late of the day.

The system downgraded to CS

until weakened at the late of the

day.

Category

Super Cyclonic

Storm

Very Severe

Cyclonic Storm

Severe Cyclonic

Storm

Cyclonic Storm

Deep Depression

Depression

Phet Cyclone (June 2010)

Weather Research and Forecasting Model

Wind Speed (kts) Forecasted (May 31, 2010) Dis = 15 km Do2

a) 00:00UTC

b) 06:00UTC

c) 12:00UTC

d) 18:00UTC

Phet Cyclone (June 2010)

Weather Research and Forecasting Model

Lat:22.5N Lon:57.8E

Lat:22.9N Lon:59.5E

Results and Discussion

Weather Research and Forecasting Model

Parameter SI WRF-ARW Range of Error

Win

d S

pee

d (

inte

nsi

ty)

May31 D D Generally, in the model

forecast period, the intensity of

the tropical cyclone was

relatively as the observed.

The system attained peak

winds VSCS at June 3, While

the model attained peak winds

VSCS at the same time.

June 1 DD – CS

Along the day

DD – SCS

Along the day

June 2 SCS - VSCS

Along the day

SCS – VSCS

Along the day

3, 4 June The system stopped as VSCS

along the 2 days

5, 6 June

The system gradually downgraded

to CS along the 2 days and

dissipated early on June 7.

Category

Super Cyclonic

Storm

Very Severe

Cyclonic Storm

Severe Cyclonic

Storm

Cyclonic Storm

Deep Depression

Depression

Mukono Cyclone

Ground Stations at Gonu Cyclone

Ground Stations at Phet Cyclone

Gonu, Phet, & Bell Design Storms

Wadi Aday Flows

Road Damage & Remediation Bridges

Road Damage & Remediation Bridges

Road Damage & Remediation Culvert & Road Pavement

Road Damage & Remediation Side Ditch

Branch from Wadi

Alansab with Area

17.85 Km2 The Study Area

Effect of Cyclones on Properties

0 100 200 300 400 500 600 700 80010

12

14

16

18

20

22

Main Channel Distance (m)

Ele

va

tio

n (

m)

Legend

WS PF 1

WS PF 2

Ground

ghala ghala

-50 0 50 100 150 200 250

14

16

18

20

22

Bridge Scour RS = 465

Station (m)

Ele

va

tio

n (

m)

Legend

WS PF 1

Ground

Ineff

Bank Sta

Contr Scour

Total Scour

0 100 200 300 400 500 600 700 80012

14

16

18

20

22

Main Channel Distance (m)

Ele

va

tio

n (

m)

Legend

WS PF 1

WS PF 2

Ground

ghala ghala

-20 0 20 40 60 80 10014

16

18

20

22

24

26

RS = 340 10

Station (m)

Ele

va

tio

n (

m)

Legend

WS PF 1

WS PF 2

Ground

Ineff

Bank Sta

.03

Effect of Cyclones on Dams

Al Ansab Dam

Inflow & Outflow Hydrographs

0

200

400

600

800

1000

1200

0 5 10 15 20 25Time (hrs)

Flo

w (

m3

/s)

InflowOutflow Initially DryOutflow Initially Half FullOutflow Initially Full

100 Yrs

Inflow & Outflow Hydrographs

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0 5 10 15 20 25Time (hrs)

Flo

w (

m3

/s)

InflowOutflow Initially DryOutflow Initially Half FullOutflow Initially FullPMF

Effect of Gonu on Road Design

128 After Screening 67 North and 10 Dhofar 105 Rain stations

Effect of Gonu on Road Design Rainfall

Item Old Manual, (1994

and Its addendums)

New Manual (After Gonu) 2010

IDFCs One for All Oman Sultanate of Oman is divided to four zones. Each zone has its own IDFC

I (mm/hr) corresponding to 100 Yrs at 0.25 hr

140 174 (for IDFC of Zone 1)

Gonu Effect ----

If the catchment has a time of concentration less than 2 hours, there is no need to include cyclone effect (The manual IDFCs will be used). While if the time of concentration is more than 2 hours, cyclone effect should be taken into consideration (The manual IDFCs will not be used)

Effect of Gonu on Road Design Flood Estimation

Item Old Manual, (1994 and

Its addendums) New Manual (After Gonu) 2010

Used Methods

Rational and old set of Empirical equations. The regression equations are generated using very limited rainfall and flow records

Rational, SCS Unit Hydrograph, and new generated set of Regression Equations. The regression equations are generated using huge number rainfall and flow records measured all over the Sultanate and taking into consideration Gonu effect

Limits

Rational method used for catchment areas less than or equal 10 km2

Rational method used for catchment areas less than or equal

1.3 km2

The Empirical Equations are used for catchments larger than 10 Km2

SCS unit hydrograph method is recommended for medium and large catchments

Effect of Gonu on Road Design Flood Estimation

Item Old Manual, (1994 and

Its addendums) New Manual (After Gonu) 2010

Regression Eqn ----

Two sets of regression equations are recommended for all catchment sizes (one for All Oman except Dhofar while the other one for Dhofar region). These equations should be used in conjunction with Rational or SCS unit hydrograph method

Effect of Gonu on Road Design Culvert

Item Old Manual, (1994 and Its

addendums) New Manual (After Gonu) 2010

Dimensions

Pipe 600 – 1050 mm Pipe 1000– 1500 mm

Box S (1-4 m),

H (max 4 m) Box

S (1-4 m), H (1.5-4 m)

Return Period

Primary road

1 in 50 Yrs

National & Arterial Road

1 in 50 Yrs Secondary

road Secondary

road

Local Road

1 in 20 Yrs

Distributor Road

1 in 25 Yrs Access Road

Access Road

Effect of Gonu on Road Design Culvert

Item Old Manual, (1994 and

Its addendums) New Manual (After Gonu) 2010

Min. Overburden 300 mm 600 mm

Max. Upstream Water Depth

1.5 culvert depth 1.2 culvert depth

Protection No recommended

Protection

Upstream

Length of protection is 3 m of loose riprap with filter

Downstream

Length of protection is 3 – 10 Culvert Depth of loose riprap with filter

Effect of Gonu on Road Design Bridge

Item Old Manual, (1994 and Its

addendums) New Manual (After Gonu) 2010

Protection ----

Heavy protection using at least 1.5 m depth of loose riprap and filter with length varied with computed scour

Return Period

Primary road

1 in 100 Yrs

National & Arterial Road

1 in 100 Yrs

Secondary road

Secondary road

Local Road

Distributor Road

Access Road

Access Road

Effect of Gonu on Road Design Irish Crossing

Item Old Manual, (1994 and Its

addendums) New Manual (After Gonu) 2010

Protection Mortared and loose riprap

Using R.C. cutoff with 1 m depth for the most dangerous type in addition to at least 1.5 m loose riprap with the same depth

Return Period

Primary road

1 in 50 Yrs

National & Arterial Road

N/A Secondary

road Secondary

road

Local Road

1 in 20 Yrs

Distributor Road

1 in 25 Yrs Access Road

Access Road

Risk Management

What to do before and during a cyclone?

Have your dwellings checked before a cyclone season starts and carry out whatever repairs that are needed

Talk to children and explain about cyclones without scaring them

Create storm awareness by discussing effects of a cyclonic storm with family members so that everyone knows what one can and should do in an emergency

Keep your valuables and documents in containers, which cannot be damaged by water

Risk Management

What to do before and during a cyclone?

Keep information about your blood group

Keep lanterns filled with kerosene, torches and spare batteries. These must be kept in secure places and handy

Make plans for people who are either sick, suffer from disabilities, aged and children

Store up at least seven-day stock of essential food articles, medicines and water supply

Risk Management

What to do before and during a cyclone?

Keep blankets & clothes ready for making beds. Also keep cotton bandages and several copies of photographs of family members in case they are needed for identification purposes after the storm

Store some wooden boards so that they can be used to cover windows

Keep trees and shrubs trimmed. Remove damaged and decayed parts of trees to make them resist wind and reduce the potential for damage. Cut weak branches and make winds blow through

Risk Management

What to do before and during a cyclone?

All doors, windows and openings should be secured

Continue to listen to warning bulletins and keep in touch with local officials. Keep radio sets in working condition. Battery powered radio sets are desirable

Evacuate people to places of safety when advised

Take steps to protect your assets

Store extra drinking water in covered vessels

Remain calm

Risk Management

What one should not do during a Cyclone?

During the storm do not venture out unless advised to evacuate

If you have a vehicle and wish to move out of your house, leave early before the onset of a cyclone. It is often best to stay at home

Avoid remaining on the top floor of dwellings. Stay close to the ground

Fishermen are advised not to venture out into the sea. They should keep boats and rafts tied up in a safe place

Risk Management

What one should not do during a Cyclone?

Avoid taking shelters near old and damaged buildings or near trees

Do not touch power lines. One may get electrocuted

Risk Management

What to do after the storm?

Watch out for broken glass and other sharp items in debris

Watch out for snakes and insects. Try to call for help

Listen to the advice of local officials and emergency workers

Be sure that the storm has subsided before venturing out

It is advisable to wait for the "all clear message" on radio and TV networks

Risk Management

What to do after the storm?

Wait for emergency relief teams to arrive. It may take a little time before relief becomes effective

Stay away from flooded areas

Fishermen should wait for at least 24 hours before resuming fishing

Volunteer to help people who may need assistance