The tsunami devastated the coastline of Sri Lanka, impacted several protected areas managed by the Department of Wildlife Conservation (DWC), namely Ruhuna National Park Blocks I and II. Yala East National Park, Bundala National Park, Hikkaduwa Marine National Park, Pigeon Island Marine National Park, Kudumbigala Sanctuary, Nimalawa Sanctuary, Lunama-Kalametiya Sanctuary, proposed Rekawa Sanctuary and Turtle Refuge and Kokilai Sanctuary.
In view of this, the Director General of DWC appointed a seven member committee under his chairmanship, to assess the impact of tsunami on these protected areas and to make necessary recommendations for monitoring the recovery of these ecosystems as well as to identify short and long-term restoration activities that need to be undertaken by the DWC to ensure the long-term viability of these protected areas.
The committee comprised H. D. Ratnayake, Co-chair Person (DWC) S. R. B. Dissanayake (DWC), Dr. Channa Bmabaradeniya (IUCN Sri Lanka), Ravi Corea (Sri Lanka Wildlife Conservation Society) Dr. Prithiviraj Fernando (Centre for Conservation and Research) Prof. S. U. K. Ekaratne (University of Colombo), Dr. U. K. G. K. Padmalal (Open University of Sri Lanka) and Dr. Devaka Weerakoon (University of Colombo).
The Marine National Parks received little direct impact. However, they suffered from secondary impacts such as smothering of coral reefs by siltation resulting from turbulence created by wave action as well as runoff from land, and damage arising from man-made structures such as fish nets and concrete pillars washed out into the ocean with the receding wave.
The impact on terrestrial ecosystems though considerable, was localised to low lying areas mostly associated with lagoons and estuaries.
In the Ruhuna National Park Block 1, the area impacted inclusive of the beach, was 790 hectares. Nine major sites of sea incursion were identified. These were Palatupana-goda kalapuwa, Kuda Seelawa, Maha Seelawa, Uraniya, Buttuwa, Beeri kalapuwa, Patanangala, Gona Lahaba and Kalliya, all of which are lagoons or bays with direct sea frontage.
In the Ruhuna Block II six main areas of impact were identified, namely, Yala wela, Pillinewa, Agara Eliya, Uda Pottana, Gajabawa, and Kumbukkan Oya estuary. In Yala East, the Kumana lagoon was impacted by the tsunami wave. Apart from this, the Lunama-Kalametiya Sanctuary and Proposed Rekawa Sanctuary and Turtle Refuge were considerably damaged. In all of these areas the vegetation was impacted much more than large animals or birds.
Three types of impacts on vegetation were identified. The most obvious was the complete or partial uprooting and breaking of trees due to the force of the wave close to surrounding the shore, and along the central region of flooding, leading to death, complete drying and subsequent defoliation of trees.
The other two types of damage were deposition of sand carried inland with the wave, and inundation with seawater, which heavily impacted the understorey vegetation such as grasses and herbs.
A number of fresh water tanks and water holes in Yala Block 1 were impacted to some degree by the tsunami. Pattiyawala, Diganwala, Yala Tank, and a number of smaller water holes were completely inundated, and the Patanangala and Uda Pottana tanks were breached. A few other water holes received minor incursions of seawater but were not impacted to any significant degree. While small patches of mangrove vegetation such as was in Maha Seelawa were almost completely destroyed, the larger tracts as in Pillinewa, Gajabawa etc. were relatively intact with damage only to areas close to the sea.
The direct impact on animals was less pronounced compared to the vegetation. Very few large animals were found to have perished due to the tsunami. However, small saline sensitive animals such as land snails and frogs, as well as small mammals and reptiles such as rats, mice, snakes and lizards have been heavily impacted.
Some animals like birds, small mammals and reptiles appear to have benefited from the damaged vegetation as they were observed to use the tangled masses of vegetation as nesting sites and hiding places. It was observed that most of the terrestrial ecosystems have already started to recover, especially the grasses.
Another important finding of this initial assessment was that natural ecosystems have functioned as the first line of defence against the tsunami wave. Especially the sand dunes have withstood the force of the wave very successfully, and if not for them, the southern and southeastern coasts would have received a higher level of damage.
Other coastal and offshore ecosystems such as beach vegetation, mangroves, and coral reefs have also provided protection to the coastline where these ecosystems were preserved in a relatively good condition. On the other hand in areas where natural ecosystems have been degraded due to over utilisation, the damage to the coastal areas has been more extensive. It has also become apparent that these natural ecosystems can offer a greater resistance against this kind of natural disaster rather than man-made structures such as breakwaters and rip rap structures that are in place to prevent erosion.
Based on the findings of this initial study, the committee members have also provided number of recommendations as to what actions are needed to restore the natural ecosystems in the impacted protected areas.
Once general recommendation that emerged from all the studies is the need to remove artificial debris from all impacted areas. This action has become critically important in the off shore areas such as Hikkaduwa Marine National Park where the artificial debris that got washed out from the land has become a major threat to the coral reefs.
It was also felt that information on the natural recovery process could be offered as a part of the visitor experience to the impacted National Parks, and to use this opportunity to create awareness among park visitors as to the impacts of the tsunami on the park, including the establishment of a tsunami exhibit in the Ruhuna National Park.
It was also decided to carry out a limited amount of restoration work for facilitate functional needs such as clearing of small areas to improve road accesses and wildlife viewing. Finally it was decided to establish a long-term monitoring program in selected sites of the impacted protected areas to systematically investigate and document the response of natural eco-systems to tsunamis and the recovery process. "