Dahdouh-Guebas, F.

Hettiarachi, S.

Jayatissa, L.P.

Koedam, N.

Rans, G.

Open Marine Archive

148 
 
Investigation of possible bioshields to protect vulnerable sections of the Sri 
Lankan coast 
 
G. Rans1, L.P. Jayatissa2, S. Hettiarachi2, N. Koedam3 & F. Dahdouh-Guebas1,3 
 
1Laboratory of Systems Ecology and Resource Management, Université Libre de Bruxelles, Av. F.D. Roosevelt 
50, B-1050 Brussels, Belgium.  E-mail: fdahdouh@ulb.ac.be / Guillaume.rans@ulb.ac.be 
2Department of Botany, University of Ruhuna, Matara, Sri Lanka. 
3Laboratory of Plant Biology and Nature Management, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, 
Belgium. 
 
Abstract 
 
The 26th December 2004, a tsunami generated by an earthquake of intensity of 9.3 on the 
Richter scale hit the coastal of peninsular countries along the Indian Ocean. It caused 
227 898 deaths along the countries affected. Some researches and publications hypothesized 
that coastal vegetation such as mangroves, if wide enough, could provide a protection against 
the flood and reduce the disastrous effects of a tsunami. 
The aim of the present study was to create a vulnerability indicator to classify the entire coast 
of Sri Lanka against this kind of extreme events. To achieve this, a visual classification of 
land cover was done for the entire coastal area of the island using Google Earth imagery and 
ground-truth. The Global Digital Elevation Model (GDEM) from ASTER satellite data was 
used for elevation data.  Based on these two datasets and data from literature on wave height 
and friction, a vulnerability indicator and vulnerability maps were created. The field study of 
bioshields was done based on literature and on field work realized in July and August 2010. 
The results show that the model can realistically detect the affected and non affected area on 
the coast. Vulnerability among coastal areas varies between 12 and 88%. Caveats of the 
model include the lack of variation of tsunami wave height along the coastline and 
overestimation of vulnerability where water bodies occur beyond the coastline. The 
investigation of potential bioshields reveal that the most interesting barrier which can be built 
is a mix of vegetation between Pandanus odoratissimus L. and Casuarina equisetifolia L. as 
it can provide a maximum effect of mitigation against the flood. 
 
Keywords 
tsunami, bioshield, vulnerability indicator, land use/cover, mixed vegetation  
  


Investigation of possible bioshields to protect vulnerable sections of the Sri Lankan coast

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