Flood Risk Management in Hat Yai, Thailand

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Flood Risk Management in Hat Yai, Thailand

• By Royal Irrigation Department

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The most rapid economic growth city, and the most
populated urban area in Southern Thailand
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One of Largest commercial and tourist city in the
Southeast Asia region
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The center of trades of the Southeast Asia
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Location of Utaphao river basin and
characteristic of the river basin.
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High Frequency of Flood Risk
Hat Yai had been under a series threats of floods
for many years

• 1833 1916 1942 1959 1961 1962 1966 1967
  1969 1972 1973 1974 1976 1981 1983 1984
  1988 2000 2003 2008 2009
• Floods occur almost every year !!!
• Big floods 1973
• 1983 1,000
  Million THB
• 2000
  massive losses

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Flood Mitigation of Utaphao river basin and Hat
Yai city

• 1. Structural measures
• Improvement of natural water drainage system,
  natural canal extension to improve drainage
  efficiency of canal for a distance of 46.90 km.
• Flash flood drainage management, main drainage
  system work including a water gate to transfer
  water from Utaphao canal to Songkhla lake (length
  21.343 km).
• A water diversion canal (length 26 km) and water
  gate will drain water from Utapho canal outside
  Hat Yai town and relief flood in lower Utaphao
  canal.

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Flood Mitigation of Utaphao river basin and Hat
Yai city

• A diversion canal was built to discharge excess
  flow directly to the sea.
• Construction of embankments, improvement of
  drainage canals
• Reservoir area improvement
• Reservoir area water way construction
• Provision of drainage pumps.

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flood gate
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Diversion canal
Flood gate in main canal
Flood gate in sub-canal
Diversion sub-canal

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2. Nonstructural measures

• Monitoring the climatic and hydrologic situation
  of the Utaphao River using information from Thai
  as well as foreign meteorology websites.
• Water situation prediction and mitigation consist
  of climate, rainfall, discharge, water level
  monitoring in reservoirs, rivers and typhoon.
• Water management in the watershed to indicate
  mitigation and flood warning level.
• Public warning for advance flood preparation to
  relief damage of prosperities and lives.
• Water analysis center at Songkhla Irrigation
  project.

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High Potential of Observations and monitoring

• Meteorology TMD
• Doppler Radar
• Regional Met. Center to be a major department to
  closely monitor / give essential advices/
  warnings
• Dense observation networks, accessible satellite
  data, and
• 4. Numerical Precipitation prediction Model
  (NWP/ WRF)

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Telemetering network Radar coverage
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Utaphao river basin Telemetry System

• Real-time telemetry in Utaphao river basin
  consists of one main station and 13 field
  stations.
• It measures rainfall and discharge every 15
  minutes.
• Data are sent via a VHF radio network to the main
  station for data analysis and flood prediction.
• Flood warning is provided 9 to 16 hours in
  advance.
• The efficiency of the telemetry system will be
  increased when we add a GPRS system and 5 more
  field stations.

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Telemetry System in Utaphao river basin
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Flood forecasting and warning system

• FloodWork Server was located at the Royal
  Irrigation Department Southern Regional HQ in Hat
  Yai.
• This server was linked to a telemetry computer
  which receives all of the latest observed
  hydrological and hydraulic data from the Utaphao
  basin.
• Automated forecast simulations were set up, so
  that forecast simulations are carried out at
  regular intervals, ideally just after the
  telemetry system has been set up.
• Series of client computers, connected via leased
  line network connections to the main flood
  forecesting server, were set up to display the
  results of the flood forecast simulations

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Flood forecasting system for the Utaphao River
Basin using the Floodworks software (MWH Soft)
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Flood forecasting by water level (state
correlation)

• Flood forecast and warning in Hat Yai town using
  discharge data collected at different points
  along the Utaphao Canal can provide flood warning
  in advance of 20 to 21 hours. The flood routing
  period is variable, according to discharge in
  Utaphao canal. We developed statistical
  relationships between the flood peaks of two
  hydrological stations upstream of Hat Yai city
  and used the relationship to predict floods in
  the city.
• The two stations include X.173A (37 km above Hat
  Yai town) and X.90 (14 km. above Hat Yai town).

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Flood forecasting by water level (state
correlation)
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Water management by pump setting
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Assistance/ support needed in UFRM
Guidances technical supports

• 1. Expertise in QPE/ QPF development and
  improvement

• 2. Technology/ expertise in Flood Modeling
  improvement and inundation flood map

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• Conclusion
• To reduce losses of lives and economy due
  to floods in city, urban flooding management
  strategy from meteorological aspect needed to be
  formulated and implemented properly.
• The disastrous impacts can be managed
  .by suitably implementing flood management
  measures, with collaborative efforts of all
  sectors of the whole community.
• Hat Yai is ready to participate in the
  Pilot City in the UFRM program of Typhoon
  Committee

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THANK YOU
Aerial view of cars and trucks at higher ground
along the bridge flyover
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