Conditions for Debris Flow Occurrence
- Sufficient sediment
- Steep enough slope
- Sufficient rainfall
Understanding Debris Flow and Large-scale Landslides
Debris Flow
When heavy rainfall occurs or river channels are blocked, large amounts of mud, sand, and rocks rush down gulleys or streams, causing severe disasters.
Landslide
An unstable slope suddenly collapses due to factors like rainfall or earthquakes.
Land Slip (Creep)
The entire land mass slowly slides due to the influence of groundwater, affecting a larger area.
Large-scale Landslide
A large-scale landslide is defined if one of the following conditions is met:
- The landslide area exceeds **10 hectares**
- The volume of earth reaches **100,000 cubic meters**
- The landslide depth is **10 meters or more**
Conditions for Debris Flow Occurrence
Locations Prone to Debris Flow Disasters
- Collapse zones in the upper reaches
- Areas prone to collapse on both banks of the stream
- Alluvial fan area at the valley mouth downstream
Signs of Debris Flow Occurrence
- Turbid stream water
- Flow volume increases or decreases
- A "GO" rumbling sound is heard
Debris Flow Evacuation Methods
Debris Flow Evacuation Principles
- Evacuate to the local emergency shelter according to the debris flow disaster prevention map.
- Try to use existing roads.
- Evacuate towards high ground on both sides of the stream.
- Do not cross potential debris flow streams.
- Avoid passing through dangerous road sections or slope areas.
Key Point: When facing heavy rainfall, evacuate towards high ground on both sides of the stream, avoid descending towards the stream channel!
What to Do When Your Residential Area is Declared a Warning Zone
Pay attention to the issuance of Debris Flow and Large-scale Landslide Warnings
Red Warning
Please follow the arrangements of the township/city/district office and local police/fire department to evacuate to a safe location.
- Issuance Condition: Actual rainfall > Warning threshold
- Response Action: Local authorities should advise or force evacuation and provide appropriate resettlement.
Yellow Warning
Residents should observe environmental changes, continuously monitor the latest public broadcast news, and keep household communication channels open.
- Issuance Condition: Forecasted rainfall > Warning threshold
-
Response Action:
- Local government should issue evacuation advisories.
- Preventive evacuation is recommended for individuals with mobility issues and those requiring regular medical attention.
Pay Attention to Disaster Prevention Information
Constantly Monitor Weather Forecasts
Disaster Information Express
- TV News and Radio
- Debris Flow and Large-scale Landslide Disaster Prevention Information Website
- Notification from Local Debris Flow Disaster Prevention Specialists
- Join the "Debris Flow and Large-scale Landslide Disaster Prevention Information Website" LINE BOT
-
Open Cell Broadcast Customized Disaster Prevention URL
Provides Five Core Information Items:
- Where the Warning Zone is Located
- What I Should Do
- Current Rainfall Situation
- Recommended Disaster Prevention Supplies
- Shelters and Phone Numbers
Typhoon Warnings
★ Sea Typhoon Warning
The sea warning shall be issued immediately 24 hours before the forecast 7-level wind radius of the typhoon may encroach upon the sea areas within 100 kilometers of Taiwan, Penghu, Kinmen, or Matsu. It is then issued every 3 hours, with additional releases if necessary.
★ Land Typhoon Warning
The land warning shall be issued immediately 18 hours before the forecast 7-level wind radius of the typhoon may touch down on the land of Taiwan, Penghu, Kinmen, or Matsu. It is then issued every 3 hours, with additional releases if necessary.
More Information Query
Debris Flow and Large-scale Landslide Distribution Map
Rainfall Warning Criteria
Evacuation and Shelter Map
Emergency Contact Information
- National Emergency Mobile Hotline: 112
- Local Police Department: 110
- Local Fire Department: 119
- Central Disaster Emergency Operation Center: 02-81959119
- Debris Flow and Large-scale Landslide Disaster Report Hotline: 0800-246-246
Essential Disaster Preparedness Supplies
Essential Disaster Preparedness Supplies
Families with Young Children
Milk powder, diapers, feeding bottles, towels
Lighting Equipment
Flashlight, lighter, candles, matches
Communication Equipment
Mobile phone, radio, walkie-talkie, batteries, power bank
Personal Clothing
Rain gear, shoes and socks, warm clothing, personal hygiene products
Valuables
Passbook, seal, NHI card, ID card, cash
Rescue Equipment
Rope, whistle, utility knife, safety helmet, mask
Medical Supplies
Basic first aid supplies and personal medications
Food and Drink Supplies
Rations, drinking water
Rainfall Observation
Rainfall Classification
- 24-hour accumulated rainfall reaches 500 mm or more
-
24-hour accumulated rainfall reaches 350 mm or more,
or 3-hour accumulated rainfall reaches 200 mm or more -
24-hour accumulated rainfall reaches 200 mm or more,
or 3-hour accumulated rainfall reaches 100 mm or more -
24-hour accumulated rainfall reaches 80 mm or more,
or 3-hour accumulated rainfall reaches 40 mm or more
Rainfall Perception
Hourly
10~20mm
10~20mm
Feet get wet even with an umbrella outside, puddles form on the ground
Hourly
20~30mm
20~30mm
Body gets wet even with an umbrella, water accumulates on roads
Hourly
30~50mm
30~50mm
Rainfall is like pouring from a bucket, roads resemble rivers
Hourly
50mm or more
50mm or more
Rainfall is like a waterfall, an umbrella is completely useless, vision is completely obscured
Self-Help Disaster Prevention Actions
Pay Attention to Disaster Information
- Pay attention to weather reports and debris flow and large-scale landslide warning messages
- Maintain contact with family, friends, and evacuation personnel
- Clear drainage ditches and ensure water channels are unobstructed
- Monitor rainfall changes and understand the local rainfall warning criteria for debris flow and large-scale landslides
Evacuation Preparation
- Inspect home environment safety, close windows and doors securely
- Prepare emergency evacuation bags, personal clothing, and important documents
- Continue to monitor messages regarding debris flow and large-scale landslide warnings
- Vulnerable groups and areas prone to isolation should evacuate early
Evacuation and Withdrawal
- Carry emergency evacuation bags, personal clothing, and important documents, and prepare to evacuate
- Evacuate to an emergency shelter; if there is a risk of disaster expansion, evacuate to an off-site accommodation center
- Inform relatives and friends that you have evacuated to a shelter
- Leave relevant messages at your home
- When flood waters are strong and reach knee depth, walking becomes extremely difficult even for adults
- Floodwater is usually brownish and turbid, making it impossible to see road edges; use a stick to check underfoot
Wait for Warning to be Lifted
- Wait at the shelter until the debris flow and large-scale landslide warning is lifted
- Follow the instructions of the local government to return home safely
Public Disaster Prevention Education
Debris Flow Warning Tip / DIY Rain Gauge
★ Materials
2-liter plastic bottle, gypsum (or cement, wax), utility knife (or scissors), ruler (15 cm)
Method 1
1. Cut off the curved upper part of the plastic bottle.
Method 2
2. Affix the ruler to the middle straight section of the bottle body.
Method 3
3. Fill the irregular bottom section (about 6 cm below) with gypsum to fix it and increase weight to prevent tipping.
Method 4
4. Move it outdoors when it rains to observe the accumulated rainfall. Pay extra attention when 24-hour rainfall exceeds 15 cm.
Self-Help Disaster Prevention Community
Land Typhoon Warning Issued
- Prepare an escape bag, personal clothing, and important documents
- Pay attention to weather reports, radio, and television messages
- Contact family members, friends, and evacuation team members
- Clear drainage ditches and ensure water channels are unobstructed
Debris Flow Yellow Warning Issued
- Vulnerable groups should evacuate early
- Inspect home environment safety, close windows and doors securely
- Carry an escape bag, personal clothing, and important documents, and prepare to evacuate
- Continue to monitor weather reports, radio, and television messages
Debris Flow Red Warning Issued
- Carry an escape bag, personal clothing, and important documents
- Evacuate to a safe shelter
- Inform relatives and friends which shelter you have evacuated to
- Leave a message at your home
Stay Away from Dangerous Environments
1
Do not build houses on steep slopes
2
Do not build houses on dip slopes prone to sliding
3
Do not build houses on debris flow river banks or areas susceptible to headward erosion
4
Do not build houses on slopes with active faults
5
Do not build houses in collapse areas or areas with potentially fractured strata
6
Do not build houses on river fan deposits or waste dumps
7
Familiarize yourself with the debris flow disaster prevention map and evacuation routes, and prepare for disaster prevention
8
Debris Flow Warning Sign
9
Rain Gauge
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