NBRO stresses need to use safe construction methods:

More public awareness needed

By Dhaneshi Yatawara

On the evening of October 22, Janaka Sampath of Hepanakanda in Alawala in the Gampaha district returned home with his son Sandun 8, to encounter the nightmare of his life. Hundreds of people were gathered around his home which had taken away his 2 1/2 year old daughter, forever. The land above their house, built on a risky slope, had slided on to the house collapsing it and severely injuring his wife, Sandya Rajapaksa and killing his baby daughter Achintha Divyangani.

The death of Achintha 2 1/2 alerted the risky situation the area faced in being prone to natural disasters, although it was not in the alerted list. Achintha's tragedy hilights the need for disaster resilient habitats with strategies going beyond the already known alerted areas. Several years ago, The National Building Research Organization (NBRO) issued a list of ten districts identified as risky areas prone to landslides. The districts are Ratnapura, Kegalle, Kalutara, Galle, Matara, Hambantota, Nuwara Eliya, Badulla, Kandy and Matale.

Hepanakanda in Alawala is located bordering Gampaha and Kegalle districts, closer to the latter. Under the NBRO Kegalle is an alerted area.

The NBRO states most of the houses in this area are insecurely constructed on a nearly 40 degree slope. According to the guidelines for construction in landslide prone areas issued by the NBRO, no construction is recommended in a land with a slope of more than 31 degrees. Such lands will have a slope of more than 60%. Lands with 8% - 60% slope (5 degrees to 31 degrees slope angle) could have constructions under strict guidelines. In Hepanakanda, where the recent disaster took place more than 25 houses are built on steep slopes without any landslide mitigating techniques.

Anyone constructing a building or a house in a landslide prone area should do so in a way that would not trigger a landslide. The Disaster Management Ministry has already issued circulars to the local authorities of landslide prone districts to consult the Ministry before approving constructions.

In Sri Lanka landslides are due to man-made reasons. Irresponsible use of land led to many landslides in the past. If the weight of the building does not suit the land, it could create a landslide.

Awareness

It has been an eye-opener for authorities to look into areas not included in the alerted list. "Irrespective of specified areas we need to look into all areas in the country to identify landslide prone areas," said Director General of the NBRO Dr. Asiri Karunawardhana.

"People need to specifically understand the necessity of using safe construction methods suitable to the particular land. It is for their own safety and the safety of their property," Dr. Karunawardhana said. "We are working closely with Sri Lankan universities engaged in studies on the actual situation of the country and finding new technological solutions," he added.

"We observe, the country's situation now is better than what it was. People are more concerned about precautionary methods used in constructions on risky lands," said Dr. Karunawardhana.

Is the landslide threat alert still on? Answering, the Head of Landslide Studies and Services Division of the NBRO R.M.S. Bandara said that it depends on as and when the situation arises. "It is difficult to predict with this inter monsoon rains. The intensity of the rain largely varies in this climate. So it is difficult to give a long term prediction," Bandara said.

Bandara said, that considering the number of natural disasters the country faces, buildings should be constructed in such a way to minimise the damages of the disaster or mitigate the disaster. "There should be a proper study of the nature of the disaster when constructing houses and buildings in disaster prone areas," Bandara said. Making slight deviations from standard construction methods could help to avert damages to life and property, he said. It requires thinking out of the box and needs the combined efforts of planners, construction regulatory authorities and disaster management sector, he added.

Resilient cities

Hepanakanda villagers vacate their homes Pix: M. P. Kumara, Kotadeniyawa Gr. Corr.

In Hepanakanda - the spot where the dwelling was

The mud slide

Is Sri Lanka concerned about resilient cities or any human habitation? What is a resilient city? According to the United Nations International Strategy for Disaster Risk Reduction (UNISDR) a resilient city is characterised by its capacity to withstand or absorb the impact of a hazard through resistance or adaptation, which enable it to maintain certain basic functions and structures during a crisis, and bounce back or recover from an event.

In such a situation disasters are minimised because the population lives in homes and communities with organised services and infrastructure that adhere to sensible building codes; without informal settlements built on flood plains or steep slopes because no other land is available. The local authorities and the population understand their risks and develop a shared, local information base on disaster losses, hazards and risks, including on who is exposed and who is vulnerable.

UNISDR founded the Making Cities Resilient campaign in May 2010 in conjunction with partners including the United Nations Human Settlements Program (UN-Habitat), United Cites and Local Governments, ICLEI-Local Governments for Sustainability, CityNet, the European Commission Community Humanitarian Office, the World Bank Global Facility for Disaster Reduction and Recovery and several other academic institutions and civil society groups.

NBRO has data and designs for construction plans to withstand floods, cyclones and mitigate landslide possibilities. But now it will be necessary for us to look into building plans that would withstand possible earthquakes as well. A special seminar was held recently in Sri Lanka, organised by the Disaster Management Ministry with the assistance of the Japan International Corporation Agency (JAICA). The aim was to share knowledge with one of the best disaster managing countries in the world. Mitigating disaster is compulsory as damages of a disaster can push back societies from poverty and beyond.

Earthquake

Addressing this special event, Terms of Reference of Knowledge and Experience Seminar on Disaster Management, K.L.S.Sahabandu, Chairman of the Sub Committee on Developing Building Guidelines for Earthquake Resistant Designs, of the Disaster Management Centre said recent geological studies have identified that the Indo - Australian Plate is splitting at a distance of 500- 700 km away from the southwest coast of Sri Lanka, creating a new plate margin. This may lead Sri Lanka to be more vulnerable to earthquakes in the future than what is experienced today.

Earthquake close to a city centre such as Colombo will have disastrous consequences due to its present development and population. Therefore we have understood the necessity to study the seismic effects on Sri Lanka and take appropriate action to mitigate the same," he said.

It is not possible to prevent the occurrence of an earthquake since it is a natural phenomenon. But damage can be minimised through preparedness.

The DMC formed a subcommittee to develop building guidelines for earthquake resistance designs.

The subcommittee investigates seismic activities around the country and determines characteristics of earthquakes which may occur in the future. The subcommittee also reviews the current design practice which does not generally cater to seismic resistance and develop effective design process to mitigate the effects of earthquake hazards in the future. National policy on earthquake resistance designs shall be prepared based on scientific evidence.

The Subcommittee to Develop Building Guidelines for Earthquake Resistance Designs has also made proposals to conduct studies on reviewing the seismic monitoring systems and propose improvement to the system, developing seismic hazard maps including earthquake intensities, acceleration coefficients, response spectrum, return periods, development of a 3D sub-surface model that improves the susceptibility of consequences against the possible earthquake in Sri Lanka, development of national guidelines for seismic analysis and design of engineered and non-engineered buildings in Sri Lanka.

The NBRO is carrying out a study in Colombo on how the buildings would react to any tremor on the surface. " We need a vast collection of data before arriving at a conclusion and setting up a guideline for constructing buildings to resist earthquakes," said Head of Landslide Studies and Services Division of the NBRO R.M.S. Bandara. The NBRO is collecting data of more than 5000 spots where the land has been drilled to various purposes. "We need to understand the soil profile variation to understand how that particular land would react to an accelerated vibration as well as the impact on the constructions on the surface," Bandara said.

Following the study the NBRO will establish a guideline to construct buildings suitable to withstand an earthquake.