Brace for more landslides with climate change
The risk of landslides is intensifying with the extreme weather patterns caused by climate change, the National Building Research Organisation (NBRO) has warned.
“We are already experiencing intensified rainfall in concentrated periods of time and this is believed to be linked to climate change, so we are heading for a period where there will be more landslides,” said Dr. Gamini Jayatissa, NBRO senior research scientist.
As about 20 per cent of Sri Lanka is mountainous or rocky and a third of the population lives in these areas the risks of landslides should be taken seriously, Dr. Jayatissa said.
As in the case of the Koslanda tragedy, landslides are mainly triggered by the increased pressure of groundwater held within soil or in the gaps of rock. If other factors are present, such as soil instability or an overburdened slope, a sudden torrent of rainwater seeping through the soil could trigger a landslide.
Landslides have traditionally been considered a minor type of disaster and not a common occurrence in Sri Lanka.
Until 2002, the annual average number of landslides did not exceed 50 but the data shows a sudden increase in their occurrence – almost a doubling of the figure – since 2003, according to the Sri Lanka National Report on Disaster Risk, Poverty and Human Development Relationship.
The data shows landslides increase in November, December and January as well as in May and June: thus there is a clear relationship with the two monsoon seasons.
November has the highest recorded number of earthslips, exceeding 275 incidents.
The NBRO has identified 10 districts prone to landslides: Kalutara, Galle, Hambantota, Nuwara Eliya, Matale, Kandy, Kegalle, Ratnapura, Matara and Badulla. Among them, Badulla, Nuwara Eliya, Kegalle and Ratnapura in the Southern, Uva and Central Provinces are the worst; Uva has the highest number of incidents.
Dr. Jayatissa said unplanned development and construction have put lives and properties at risk in many places and emphasised the need to take risk assessments seriously.
“It is true that space is limited, but constructing in a high-risk area is tantamount to welcoming a disaster,” he said.
The NBRO is already in the process of preparing Landslide Hazard Zonation Mapping to recognise high-risk areas that should be vacated or prevented from being settled, the scientist revealed.
Cutting down trees on slopes aggravate the problem as the root system of large trees can hold the soil together and also slow down rainfall hitting the ground, he added.
For those who have alreadysettled in hazardous areas it is very important to be watchful for early signs of landslides and act quickly, the NBRO points out.
|Families in danger zones in N’Eliya given temporary shelter For the 40 odd families in a shanty area this is not the first time, but the question is will they ever get a safer permanent abode
People living in areas identified as danger zones in the Nuwara Eliya District have been relocated to safer areas due to the continuing adverse weather conditions, a Disaster Management Department official said.
Accordingly, around 600 families comprising about 2600 people have been given temporary shelter in several camps. These include around 150 families in six camps in the Nuwara Eliya Pradeshiya Sabha area; 86 families in six camps in Kotmale; 320 families in a camp in Ambagamuwa, 26 families in a camp in Hanguranketa, and 43 families in two camps in Walapane.
Some people have sought refuge with their relatives, in temples, Hindu kovils and in community centres.
The official said arrangements have been made by respective Divisional Secretaries and Grama Niladharis to distribute dry rations and look into sanitary facilities of those housed in these camps.
R. Steven, a resident of the area said this was not the first time that families were relocated.
These families have been living in the area since the ’90s although the area had been ear marked as vulnerable to landslides by the NBRO.
Landslide warning signs
- Springs, seeps, or saturated ground in areas that have not typically been wet
- New cracks or unusual bulges in the ground, street pavements or sidewalks.
- Soil shifting away from foundations
- Ancillary structures such as decks and patios tilting and/or moving relative to the main house.
- Tilting or cracking of concrete floors and foundations
- Broken water lines and other underground utilities
- Leaning telephone poles, trees, retaining walls or fences
- Offset fence lines
- Sunken or tilting road beds.
- Rapid increase in water levels of rivers and streams, possibly accompanied by increased turbidity (soil content in the water)
- Sudden decrease in water levels of streams etc. although rain is still falling or recently ceased.
- Sticking doors and windows and visible open spaces indicating jambs and frames out of plumb
- A faint rumbling sound that increases in volume – noticeable as a landslide nears
- Unusual sounds such as trees cracking or boulders knocking together, indicating moving debris.
What to do during a landslide
- Stay alert and awake at the time of high risk. Many debris-flow fatalities occur when people are sleeping. Be aware that intense, short bursts of rain could be particularly dangerous, especially after longer periods of heavy rainfall and damp weather
- If you are in areas susceptible to landslides and debris flows, consider leaving if it is safe to do so. Remember that driving during an intense storm can be hazardous
n If you remain at home, move to a second storey if possible. Staying out of the path of a landslide or debris flow saves lives.
What to do if you suspect imminent danger
n Contact your local fire, police, or public works department. Local officials are the best persons able to assess potential danger
n Inform affected neighbours. Your neighbours might not be aware of potential hazards. Advising them of a potential threat may help save lives. Help neighbours who might need assistance to evacuate
n Evacuate. Getting out of the path of a landslide or debris flow is your best protection
n Curl into a tight ball and protect your head if escape is not possible.
What to do after a landslide
n Stay away from the slide area. There may be danger of additional slides
n Listen to local radio or television stations for the latest emergency information
n Watch for flooding, which may occur after a landslide or debris flow. Floods sometimes follow landslides and debris flows because they may both be started by the same event
n Check for injured and trapped persons near the slide without entering the direct slide area. Direct rescuers to their locations
n Help a neighbour who may require special assistance – infants, elderly people, and people with disabilities. Elderly people and people with disabilities might require additional assistance. People who care for them or who have large families may need additional assistance in emergency situations.
Source: United States Geological Survey