Natural Hazards Observer
| May 2005 | Volume XXIX | Number 5 |
Learning from Sri Lanka: A Wake Up Call for Coastal Hazards Mitigation
The devastating tsunami generated by the Sumatra magnitude 9.3 earthquake on December 26, 2004, killed over 200,000 people in 12 countries around the perimeter of the Indian Ocean. Millions of housing units were damaged or destroyed, economies were decimated, and ecosystem disruption is still being assessed. The lessons from this catastrophic disaster have worldwide implications.
I visited Sri Lanka from January 30 through February 9, 2005, as part of a quick response reconnaissance team. Our local hosts organized a field reconnaissance to locations where large numbers of people died and/or where the impact was particularly significant. Additional insights were provided by interviews with representatives from the Ministry of Urban Development and Water Supply as well as with individual survivors, business owners, and investigators at the University of Moratuwa in Colombo.
Tsunami: The Sri Lankan Experience
In Sri Lanka, the tsunami proved disastrous from many perspectives. Lives were lost, communities destroyed (housing, commercial entities, and infrastructure), and ecosystems damaged. Over 35,000 people were killed; at least 16,000 were injured. Almost one million people suddenly became homeless, and an estimated 350,000 lost their jobs, including fishermen, other informal traders, and microenterprise employees representing tourism as well as other small businesses.
High occupancy/high consequence facilities were also severely impacted. An estimated 30 hospitals and health care facilities were damaged or destroyed, making health care difficult to come by for the many injured. Additionally, 176 schools were either damaged or destroyed; luckily, since the disaster struck on a Sunday, school was not in session.
It is important to note that loss of life did not necessarily correlate with population density. In many cases it reflected inappropriate behavior and failure to evacuate. For example, when the first wave receded to expose the sea floor, large numbers of people followed the strange phenomenon to collect seashells and stranded fish. When the wave suddenly turned they were too far out to reach safety. Others died because they tried to climb onto buses or a train instead of taking refuge in nearby reinforced concrete buildings. Low-density areas characterized by abundant opportunities for spontaneous pedestrian and nonmotorized evacuation generally had lower fatality rates. Conversely, high-density places with narrow discontinuous lanes and alleys (lack of evacuation routes) trapped many people.
The northeast and southern regions of the country were the most severely affected. High concentrations of fatalities were experienced in several communities characterized by densely spaced, poorly constructed residential/commercial buildings with very narrow paths for ingress and egress. Approximately 10,000 people died in one such community.
There were other impediments to evacuation besides the lack of access routes. Numerous victims were killed or lacerated by a species of palm tree with serrated bark and very sharp fronds. The risks created by this palm were compounded by its common use, in combination with barbed wire, for fencing. Many bodies were found in front of such fences.
In addition to the human casualties and the devastation of the built environment, geomorphic changes and other coastal ecosystem impacts have been noted (but not yet fully analyzed). In several bays the beaches became narrower and lower; many of the canals and lagoons that open to the sea have been altered. Both of these changes will enable the energy from high wave events such as storms and cyclones to be transferred farther inland, making them more dangerous and destructive.
Ecosystem damage caused by past practices also interacted with the settlement patterns to exacerbate the effects of the tsunami. For example, anecdotal evidence strongly indicates a direct correlation between coral reef mining, higher amplitude and wave energy, loss of life, and building damage. Tsunami waves also appear to have entered inland with greater force in the areas where sand dunes had been graded or where mangroves had been cut.
Setting the Context
Underlying policies and regulations establish the context within which these losses occurred. A number of planning tools were identified that were notable because they were either enforced or not enforced and/or because they represent opportunities to be built upon during recovery.
- Coastal Enterprise Zone—In the 1980s a one-kilometer zone around Sri Lanka was declared an urban development zone administered by the Urban Development Authority (UDA) to encourage economic activity, such as port expansion, international tourism, and fishing. The UDA, with jurisdiction over the entire area, can apply its legal authority and laws throughout.
- Coastal Erosion Reduction Zone—A 300-meter zone was created to reduce coastal erosion, which is particularly severe on the northeastern coast. The Department of Coastal Conservation, which administers the Coastal Erosion Reduction Zone, operates under a law that gives them the authority to control construction, including designation of a safety line beyond which development is not permitted. Currently, construction must remain a minimum of 50 meters inland from the vegetation line. Guidelines also mandate creation of vegetation buffers. In the few instances where such buffers were observed, they successfully reduced the effects of the tsunami.
- Buildings codes and access standards—A high percentage of damage occurred to residences and small businesses, the majority of which were constructed by the “informal” sector. Structures built by this sector tend not to comply with commonly accepted construction standards (e.g., there was a notable lack of good mortar and or reinforcing steel). Compounding the problem, setbacks in the coastal erosion zone have not been enforced. Thus, the poorly built structures could not benefit from the protective buffering and wave dampening that may have been provided by the zone. A similar lack of quality control also extended to access routes, which in the densest of areas were either nonexistent or very narrow. Regularly spaced access to and from the ocean did not exist.
- Temporary Safety Buffer Zone—The Ministry of Urban Development and Water Supply has declared a 100-meter safety zone, which is temporarily a “no build” or a special review zone. A permanent zone will be defined to include subzones, the boundaries of which are expected to correlate scientific, site specific, and use-related variables. In some instances, areas with steeper topographic elevations may be removed from the safety zone or their setbacks may be reduced. But, where vulnerability to multiple hazards, such as cyclones and coastal erosion, is high, setbacks may be increased.
Once characteristics of the safety zone are more specifically defined, it will become scientifically feasible to define “appropriate” and “inappropriate” uses for the hazards zones. Some structures, built to international standards of resistance and capable of providing shelter-in-place for cyclone or tsunami events, may be allowed while high occupancy/high consequence facilities, such as schools and hospitals, may not be.
Conclusions: Lessons from Sri Lanka
Coastal regions will always be focal points for commerce, tourism, recreation, and residential uses. As such, it is inevitable that coastal regions will be subject to development pressures and population concentrations. With this vulnerability in mind, the lessons from the Indian Ocean tsunami are particularly relevant.
Lesson #1: Education is essential to saving lives: The role of public awareness cannot be overemphasized. A significant number of fatalities occurred because people did not know when to evacuate. In the few areas that benefited from formal education (as in the case of the British schoolgirl visiting Sri Lanka who had just studied tsunamis) or prior experience and oral history, there was a noticeable reduction in the number of casualties.
The following evacuation questions should be addressed in outreach education in preparation for an event:
- Who should be educated? Populations worldwide must be educated. Virtually anybody can find themselves on a coastal road, train, or in a port, coastal hotel, restaurant, or business. Many of the fatalities on December 26 were foreign tourists on winter holiday.
- When should an evacuation take place? Education should stress key indicators and emphasize the need for timely decision making.
- What are the evacuation routes? Access routes must be provided and maintained free of obstructions.
- Where will evacuees go? Sites to accommodate refugees for 12-24 hours must be identified within a 5 to 10 minute walk of the projected hazards area.
Lesson #2: Multihazard-based decision making is key to risk reduction: Patterns of loss indicate that in Sri Lanka, like many other coastal regions throughout the world, multiple geological and atmospheric hazards tend to be coterminous, which reinforces the risk of repetitive loss. This vulnerability highlights the value of applying predictable and science-based criteria to guide decision making for coastal regions. The importance of multihazard planning that considers reciprocal implications and risks of ecological disturbances, such as those caused by coral reef mining, and vulnerability to such hazards as tsunamis, earthquakes, cyclones, and storm waves is an essential aspect of loss reduction.
Clear identification of the risk factors is only the first step in establishing risk-based development criteria, including restrictions. Avoidance practices through mandated open space and setbacks may however be insufficient to both reduce ongoing erosion and encourage safer development patterns. Clearly, articulated goals must guide future development. Construction in compliance with enforced regulations is essential. The use of nonstructural tools, such as vegetation management, to create energy reducing buffers is also necessary. By combining a variety of loss reduction mitigation strategies, communities can improve their coastal environments to withstand “unexpected” pressures from both nature and humans.
Jane Preuss AICP
Planwest Partners