URBAN FLOOD AND INUNDATION IN HANOI CAPITAL PLOBLEMS, MEASURES AND CLIMATE CHANGE ADAPTATION Urban Flood Risk Management in a Changing Climate: Sustainable and Adaptation Chanllenges 6-10, Sept, Macao, China TRINH THU PHUONG VIETNAM NATIONAL CENTER FOR METEO-HYDROLOGICAL FORECASTING

- HaNoi capital of Vietnam - Located in Red river Delta. - Area: 3.324,92 km 2 - Population: (2009). - Red river (the second largest river of Vietnam) flows throught Hanoi city, come into the sea with annual capacity (60 billions m3) - The city belows the water level - HaNoi is prevented by a solid dykes system. The dike system in Ha Noi has never been broke, even in big flood years 1971, 1996 or during the war

Total length Dyke : 3500 km LOW DELTA 97% of delta regions with dyke < 9 m 72% of delta regions with dyke < 3 m 58% of delta regions with dyke < 2 m Height in Hanoi: 15 m Dyke system in Ha Noi can stand for the flood level 13.5 m, higher than III alert : 2.5m

Ubarn flood in HaNoi can be devided into two categories 1. Local flood: very hight rainfall intensity occure and generate higher surface run –off that is in excess of local drainage capacity. Urban Flood and Inundation will happen Inundation

2. Riverini flood: heavy rainfall at upstream, big flood upstream happened and after that the watel level at downstream increase rapidly.

Climate change in Hanoi Dute to Climate change and global warming, HaNoi city may effect more big flood from upstream and heavy rainfall in city. The temperature in Hanoi rises up from Maximum total rainfall in day at Ha Noi rises up from

Total rainfall in 6 hour at Meteorological stations in HaNoi has been increased for 10 years. Met_hydrological network in HaNoi

- Infuture, from , the temperature will increase 3 o, total rainfall in dret season increase 20%, and in dry season decrease 40% Climate change in Hanoi Annual Temperature and % the changes of Rainfall in HaNoi from 2000 to 2100

Ubarnization, population growth and flood in Hanoi - In 10 years recent, the population of HaNoi go up very quikly. -The boom of urbanisation has led the city a giant contruction field and inefficient solid wastes proceesing and consequencyly lead to inundation and stagnage of under ground water.

- The rainfall runoff happen qickly exceed the capacity of HaNoi’s drainage -Landuse: Many pond and low land areas or small lakes regulation were replaced or narrowed by construction and building which leads to the reduction of water restore capacity. Surface runoff on the road at Nguyen Khuyen str, HaNoi city (13/7/2010) Depth in undation from m

Some serious flood features in Hanoi city in recent times -Because of climate change, The intensity per hour and total rainfall in a day at Hanoi trend to increase. The inundation will occurred more than usual and takes long time. - From 30 October to 1 November 2008, the extremely heavy rains over mm were recorded in Hanoi area (3 days). The rain in Hanoi was concentrated in a short period with the highest intensity in more than 100 years passed. -Deep inundation about 1,5-2,5m during 5-10 days in Hanoi. -10 People died in this flood. -Total Points inundation in HaNoi are about 30

Boating in Ha Noi city in 2008 Inundation from 0,5m-1,0m, many areas from 1-1.5m.

Traffic jam in Kim Ma street (2008) Hoan Kiem lake, 1 Nov 2008

The rainfall over 100mm caused inundation in Hanoi with deep about 0,5-1,0m. -The duration of inundation: 1days Inundation 17/8/2009

- On the morning, 13 July 2010, from 6.45 Am to 10 Am, A heavy rainfall occurred. Total rainfall recorded in the central of Ha Noi from 100 mm- 153mm (3 hours). - There are 23 points inundation from 0.3 m -1m, especially many main streets at center HaNoi. 13/7/ People died in Ha Noi in this inundation. -Duration of inundation: 5 hours

13/7/2010 Kim Lien Tunnel Street or River?

Some main reasons of HaNoi inundation 1.The old and low capacity of underground sewage irrigation cannot afford to discharge water when rainfall is higher than 172mm/2 days (86mm/1 days)- Stage I of the Hanoi drainage project (supported by JICA). But infact, many heavy rain occurred in short time with total rainfall is higher than 172mm.So, Ha Noi is always flooded Inundation occurred in HaNoi X>86 mm/day

2. Because of the ubarnization, landscape change by contruction. Surface runoff on the road appears earlier. 3. HaNoi haven’t got an ubarn flood management system and decision maker. The contaction between National Met-Hydrological Forecasting service and Some oganization (responsible for water resources) is not available.

Current status drainage of Hanoi Four companyies have been established to assit the responsibility water resources. - Hanoi water Business Company, responsible for management, operation of water supply in urban areas of Hanoi city. - Hanoi sewerage and Drainage Company, responsible for operation and maintenance of the sewerage and drainage system - Environmental Company: collection and processing of domestic water - Design Copany for ubarn Public work, carriout all the design work for distribution pipeline and home connections

Current status drainage of Hanoi Drainage system in Hanoi include water from rainfall and wastewater.

Current status drainage of Hanoi Downtown of HaNoi city: 1. The main drainage directions are To Lich river and Nhue river. +at To Lich basin: Pumping water to Red river by Yen So station with capacity 45 m3/s; Dong My station and throught Thinh Liet Dam. Yen So station with 11 water pumps

Downtown of HaNoi city : + at Nhue basin: Pumping water to Nhue river by Dong Bong, Xuan Dinh, Thanh Binh station with capacity 23 m3/s (while need 114 m3/s) Red river Current status drainage of Hanoi

Downtown of HaNoi city : Small trenches for irrigation and 32 small river in city gather the overflow on the road.

Measures to mitigate the Hanoi ubarn flood, inundation and climate change adaptation in Hanoi 1. Structural measures: Flood control in Hanoi urban Build upstream Reservoirs ( prevent Ha Noi capital from 500 years return periods) Strengthen the dike system to protect Red riverl delta Dredging and clearing river bed and Constructing the rainwater collecting works; upgrated the drainage system Plan and protect upstream forests Cooperation between National, Province, District, commune must be well (including infrastructures, equipments, and operation & management)

Some results of strutural measure for ubarn flood in HaNoi 4 big reservouirs system upstream Hong river delta have reduced the volume of flood and maximun of watel level at HaNoi station in flood. Thac Ba reservouis operated (0.5 bil for flood control) Hoa Binh reservouis operated (3 bil for flood control) TuyenQuang res operated (3 bil for flood control) Son La operated (3 bil for flood control )

Measures to mitigate the Hanoi ubarn flood, inundation and climate change adaptation in Hanoi 2. Non-Structural measures: Mitigate inundation and flood lossed in Hanoi Urban planning in long time Strengthening of the forecast capacity Developing the transferation information throught TV, radio, webside and VOV traffic Changing and improving awareness of public involved in monitoring the management and resolution of flooding, protect environment

Flood Management cycle

Investment project for Irrigation in Ha Noi 1.The stage I of Irrigation project in Ha Noi from , Japan International Cooperation Agency (JICA) funded : + Resolved the inundation in HaNoi with the rainfall less than 172 mm/2days (50mm/2h) + Built the drains through the dike 45m3 / s; discharged into the Red River channel 90m3/giay; Yen So lake regulation 3.78 millions m3. + Dredging and river embankment 4 main small rivers: To Lich, Lu, Set and Kim Nguu (33km).

2.The stage II of Irrigation project in Ha Noi from , Japan International Cooperation Agency (JICA) funded: + Increase the capacity of pump Yen So staion from 45 m 3 /s to 90 m3/s (8millions m3/day) + Resolved the inundation in HaNoi with the rainfall less than 310 mm/2days + Improved 12 regulation lakes Investment project for Irrigation in Ha Noi

3. The project "Construction and renovation of three pump stations and drainage Co Nhue, west of Hanoi Dong Bong" by the Belgian Government funding has been approved by the city allocated to Sewerage Company Hanoi investor. (Co Nhue pump will be built with a capacity 12m 3 /s, Dong Bong I, Bong Dong II pump is 9 m 3 /s in 2012) Investment project for Irrigation in Ha Noi

Forecasting and warning inundation in HaNoi Foreign Country: -Project: Water quality monitoring work under dry and wet wether conditions in the downtown of Hanoi city, Dr. Hiroaku Furumai, Research Center of Water Environment Technology, University of Tokyo. Pilot Point is downtown of Ha Noi, simulated the inundation in 2003 and 2008.

In Vietnam -Using Quantitative Pricipitation forecast (from Numberical Weather Model, radar and sattelite) as the input of hydrological model) -Forecasting the water level at Ha Noi station with the lead time from 24 hours to 48 hours using hydraclic model. Strengthening of the forecast capacity

URGENT PROJECT IN VIETNAM FROM BUILDING THE RAINFAL AND FLOOD EARLY WARINNING SYSTEMS, FORECASTING AND WAINING DETAIL HANOI INUNDATION from Modenization the Met_hydrological network observation +Supplied the hight technology for Mydro_Meteorological nowcasting.

- Weather forecasting in short time using HRM and ETA hight resolution model 14kmx14km. Pilot selection: HaNoi Capital -Using distributed hydrological model MARINE (French) for Flood forecasting and warnining in short time. Pilot selection: Hong -Thai Binh river system. -Using hydraulic model MIKE 11, MIKE 21, MIKE Urban and MIKE GIS Flood forecasting and warnining in inudation in downtown HaNoi.

- Building 412 rainfall stations (28 points for Muity-reservoirs operation - Improvement the infrastructure for 25 hydro stations at Hong river -Improvement and rebuilt 127 Meteorology auto- stationst in the North to meet the density of stations: 30-60km

New Auto rainfall stations network in the Project

-Improvement and rebuilt 127 Meteorology auto- stationst in the North to meet the density of stations: 30-60km. - Upgrate the rain gause network in Hanoi for nowcasting (rainfall, flood, inundation)

Making hazard map: flood and inundation Map in Hanoi -Terrain survey and inundation points investigation in HaNoi (total day Rainfall>100 mm) Depth inundation m Depth inundation m Depth inundation m

- Setting up hydrological urban model for caculating and early wairning flood and inundation in Hanoi - Digitize floods and inundation mapping in hight resolution ( for all city, for districts…)

Rain gauge, radar, settalite Hydrological model forecast Via: wesite, TV, radio, Voice of Vietnam traffic channel. To: govement, central and local, Central Committee for Flood an,d Storm Control in Hanoi, Hanoi sewerage and Drainage Company Flood bulletin, inundation Map in realtime Diagram of flood and inundation warning in Hanoi