Michael DiGregorio PhD

Planning for Climate Resilience:

learning from typhoon Mirinae

Typhoon Mirinae: 30 Oct-2 Nov 2009

• On the morning of 2 November 2009, tropical storm Mirinae, with wind speeds of 109 kph, makes landfall in Phu Yen province. It is the 11th tropical storm to hit Vietnam that year.

• Deputy Prime Minister Hoang Trung Hai issues disaster preparation instructions on 30 October. In Binh Dinh, schools are closed on 2 November and people are advised to prepare for the storm.

•Phu Yen, the province hardest hit by Mirinae, reports that floods and strong wind has claimed at least 78 lives. In Binh Dinh, 22 people are reported dead and 3 reported missing. In Khanh Hoa, further to the south, 14 deaths are reported.

• Between 2-3 November, 801 mm of rain falls in Van Canh, Binh Dinh.

• In late October, Bùi Minh Tăng , director of the Central Storm Forecasting Agency, announces that the storm is powerful, rapid and will produce up to 400 mm of rain in Central Vietnam.

• Provincial governments report a total of $280 million in damage to property.

Rainfall by hour, Van Canh & Quy Nhon 2-3/11/ 2009

4-5 pm 8-9 pm 12-1 am

Sông Hà Thanh

Đầm Thị Nại

Tỉnh Phú Yên

P. Nhơn Phú

TT Vân Canh

TT TP Quy Nhơn

TT Diêu Trì

4-5 PM

8-10 PM

P. Nhơn Bình

7-9 PM 6-7 PM10 PM-4 AM

Typhoon Mirinae: Evolution of a Flood

Flood chronology by area. Time flood first noticed in yards. Based on interviews.

Source: http://www.aprsaf.org/data/aprsaf16_data/D3-1445_AP16_SA_Vietnam.pdf

Satellite image: 05-11-09

TT Diêu Trì

P. Nhơn PhúP. Nhơn Bình

P. Đống Đa

TT Tuy Phước

P. Bùi Thị Xuân

TT TP Quy Nhơn

P. Nhơn Hội

Ward or Commune

Damage Assessment

Coastal fisheries, boats and tackle

$373,495 including $305,470 in damage in Dong Da and $68,025 in Nhon Binh. Damage to fish ponds accounted for 88 percent of the total.

Industrial zones

$10,432,171 in damage to industrial zones in Nhon Binh ($9,937,853), Bui Thi Xuan ($440,121) and Phuoc My ($36,392).

Housing

$1,343,430 in total damage to homes. 2,061 of the 2,302 homes damaged or destroyed during the flood were in Nhon Phu.

Dikes, roads and irrigation systems

$1,445,888. The largest losses were in Nhon Phu ($481,944) and Phuoc My ($472,370). Together, Nhon Phu and Phuoc My accounted for 67 percent of all damages to dikes, roads and irrigation systems.

Agriculture and livestock

$3,183,528. In Nhon Phu and Nhon Binh, loss of livestock and loss of rice in storage accounted for a majority of the $1,760,820 in damage. In Phuoc My, loss of livestock and damage to fruit trees accounted for a majority of the $647,388 in damage.

Forestry$2,708,023. 98 percent of the total damage occurred in Phuoc My, where 19 sq. km. of industrial forest was damaged or destroyed.

Đống ĐaNhơn Bình

Nhơn Phú

Bùi Thị Xuân

Phước Mỹ

Floods and Farming

Historical Flood Pattern:With Few Barriers in the Flood Plain, Water Drained Quickly

bridges

Van Ha RR Hwy19Hung Vuong

Thi Nai Lagoon

agricultural villages agricultural villages fisheries villages

low roads low embankmentSeasonal floods generally

rose and fell gradually over a 8-12 hour period, often at night.

During severe and extreme floods, water could easily and quickly pass over the top of low roads.

Because settlements in the floodplain were few and concentrated, floodwater could spread out over a large area.

Slope of 8 meters in 8 kilometers from Van Ha to Thi Nai allowed water to drain quickly

Floods and Infrastructure

Nhon Phu

Dong Da

Dieu Tri

Nhon Phu

Weir

Weir

Kon river

Tuy Phuoc

Nhon BinhHwy 19

Hung Vuong St.

Northern DikeEastern Dike

⏏

⏏

⏏

⏏

⏏⏏⏏ ⏏

⏏

⏏

⏏⏏

⏏

⏏⏏

⏏

⏏⏏

⏏

Typhoon Mirinae: Impacts of Infrastructure and Urbanization on Flooding

bridge

river river RR Hwy 19 & Hung Vuong dike lagoon

agricultural villages agricultural villages fisheries villages

bridge

dike

barrage

CCN KTDCĐHQT

low roads

2.0m 2.0m 2.0m 2.0m

Thi Nai Bridge

bridgedike

Flooding in the lower Ha Thanh River occurs when when the flow of water in the riverbed is greater than 1,226 m3/second.

During the 2009 flood, river flow reached 3,328 m3/second.

Barriers in floodways and insufficiant drainage capacity raised the level of flooding.

+11 cm

+03 cm

+70 cm

+07 cm⏏ Bridge

RailroadUpgraded Dike SectionOld Dike SectionMain Road

LEGEND

+13 cm+40 cm

IMPROVING DRAINAGE IS KEY TO REDUCING FLOOD RISKS

⏏ Bridge

RailroadUpgraded Dike SectionOld Dike SectionMain Road

LEGEND

⏏

⏏

⏏

⏏

⏏⏏

⏏⏏

⏏

⏏

⏏

⏏

⏏

⏏

⏏

⏏

⏏

⏏

⏏

Dong Da

Dieu Tri

Nhon Phu

Nhon Binh

Area Plan for Nhon Binh: Impacts on Flooding

Nhon Phu

If the current area plan is built as planned, a flood similar to Mirinae would produce deeper flooding.

⏏

+33 cm

+50 cm

+70 cm

+76 cm

The Area Plan for Nhon Binh proposes filling in roughly one third of the ward’s area.It also reduces the flood channel to a narrow area between Bridge No. 7 and 8, and Barrage No. 2.

Floods and Urban Development

⏏ Bridge

RailroadUpgraded Dike SectionOld Dike SectionMain Road

LEGEND

⏏

⏏

⏏

⏏

⏏⏏

⏏⏏

⏏

⏏

⏏

⏏

⏏

⏏

⏏

⏏

⏏

⏏

⏏

Dong Da

Dieu Tri

Nhon Phu

Nhon Binh

Area plan for Nhon Binh: Impacts on Flooding under Climate Change and Sea Level Rise

Nhon Phu⏏

Based on our

hydrological model, by

2050, under

conditions of Climate

Change and a Sea

Level Rise of 26 cm, a

storm similar to

Mirinae, which

produced floods

greater than 2m in

depth in most areas of

Nhon Binh and Nhon

Phu, would produce

much deeper flooding.

+41 cm

+77 cm

+90 cm

+89 cm

Hydrological impacts of urbanization

Nhon Phu

Dong Da

Dieu Tri

Nhon Phu

Tuy Phuoc

Nhon Binh

⏏ Bridge

RailroadDike/Dike Road

Main Road

LEGEND

⏏

⏏

⏏

⏏

⏏⏏⏏⏏

⏏

⏏

⏏

⏏

⏏

⏏

⏏

⏏

⏏

⏏

⏏

If all the plans for Quy Nhon are implemented, floodways would be severely narrowed,

creating the potential for overtopping in newly urbanized areas,

worsening flooding in low areas of Dieu Tri and Tuy Phuoc.

increasing risks for people living in floodways, and

Tuy Phuoc

• Manage upstream threats

• Improve flood warning and the training of community leaders

• Restore and improve drainage in the Ha Thanh River floodplain.

• Limit new residential, industrial and infrastructure development in the floodplain of the Ha Thanh River.

Recommended actions