Protecting coastal belt from erosion

By Harshini PERERA

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White foams of rippling water splashes the shore at the time the sun sets - a breathtaking sight. Many have enjoyed the blessed stretch of the calm and beautiful ocean that Sri Lanka is surrounded with. The same peaceful comforting ocean can be furious during storms or harmful when it erodes the precious land.

Sri Lanka is an island with a coastline of 1,585 kilometres and a land area of 64,000 square kilometres, situated between latitudes of 50 55’ and 90 51’ and longitudes of 790 41’ and 810 54’ East within the tropic of Cancer. The area lying within a limit of three hundred metres landward and two kilometres seaward is the coastal area which is generally low-lying and landscapes exhibit considerable variety characterized by bays, lagoons, headlands, coastal marshes and dunes. The coastal area is enriched with biological productivity, whereas mangroves systems, estuaries, coral reefs, sea grasses are aplenty.

Natural and man-made factors are the two main causes of destruction which contribute to coastal erosion. When monsoon weather approaches, as a result of fierce waves, erosion becomes intensive as a form of natural phenomenon. Fairly strong storms or gales, high-frequency waves hit the shore and a large extent of coast is washed off. In some vulnerable areas approximately 100,000 of square-metres are washed off every year both by natural and man-made causes. Engineer H.N.R.Perera, Director of the Coast Conservation Department explained that erosion by monsoon weather is a natural phenomenon but recently it has becoming more vigorous than ever probably due to the rise of the sea level as a result of global warming.

One of the major causes of man-made erosion, is the excessive sand mining. A coastline or a beach is spontaneously created when various materials are carried into the sea by rivers as a main supply of nourishment. People regardless of the damage caused to the shore, excessively remove sand from the river bed. Sand mining has increased in Kelani, Maha Oya and Kalu Ganga beds than before. Sand has become a prime material for building construction industry, and the demand for it, is also on the increase. This causes a reduction in the materials such as sand, debris it carries to the sea. Thus waves wipe out sand from the beach. Engineer Perera explained that if you visit Polgahawela area, you will see trucks driven to the bed of the Maha Oya, how people gather sand both legally and illegally. As a result, erosion in the Northern coastline has intensified where five to eight metres of landare washed off every year. In 2005, it was recorded that two rows of houses, in other words 750 metres of land was lost. Illegal sand mining, is a major cause of erosion to which an immediate remedy should be found.

Coral mining is also a major destructive cause which intensifies erosion. Lime taken from coral mining is an equally important material in the building construction industry which is in areas such as Hikkaduwa, Telwatta and Akurana. Coastal erosion can have a huge impact on the development of the country since many modes of travel, buildings, industries are centred round the coastline. The road system of a country is important to its development just as anything else. Here, the Galle road and the railway line run parallel to the coastline which invariably has to be protected from coastal erosion. In Kahawa and Seenigama areas a large stretch of Galle road and in Katukurunda, Kalutara area the railway line were washed off in 1997. Improperly erected buildings such as illegally constructed small houses are in a critical state of being washed away. It is obligatory a person who sets up a building in the coastline to get permission from Coast Conservation Department and he should set it up keeping a considerable distance from the coastline which is called the Buffer Zone. According to the size of the development and the location, public should reserve 15 to 50 metres as the Strict Reservation area.

On the other hand, the fisheries industry and tourism similarly run a risk. Prof. Liyanarachchi, Professor in Geography of the University of Ruhuna explained further how fishermen are at the risk of losing their profession just like persons in tourism. Tourism as a form of foreign income generator is flourishing as the beaches in Sri Lanka are enchanting. Along the beach wetlands, buildings are set up making plants and other species endangered. It also could root out the eco system around mangroves, estuaries, sea grasses resulting in the degradation of biological productivity. Additionally, fishing habitats will be destroyed and many fish varieties in coastal areas are endangered when mangrove system are destroyed.

Prof. Liyanarachchi further elaborated that without a suitable beach and harbour, the fishing industry will also be threatened if coastal erosion increases. The authorities would find it difficult to relocate fishermen who had lost their houses, place of work and also fishing equipment. Some vegetation like coconut are also damaged when erosion takes place.

The Coastal Conservation Department has already taken steps to reduce the damage caused by erosion using different strategies. In this regard, emergency revetments and Off Shore Breakwater are used as short term and medium term remedies. Revetments are constructed in the sea, parallel to the coastline and on a sheet of cloth by laying boulders on it. Once the revetment is built, the strength of the wave is broken before it reaches the coast. Artificial Sand Nourishment is the long term remedy. Even though it is expensive in application, Sri Lanka has employed this method in Maha Oya Lansigama area. Countries like the Netherlands have been successful in employing such long term remedies with which they were able to widen the coast further.

Coast Conservation Act of 1983 authorises Coast Conservation Department to carry out coast protection and regulate its development. One of the many responsibilities of the CCD is to carry out an annual study regarding the changes of the sea bed and the beach profile.

They also conduct programs on coast conservation in order to create awareness among school chidren and officials. those from the level of schoolchildren to officials in the departments. Meanwhile they carry out socio-economic studies on use of land. The CCD has been actively involved in Coastal Resources Management Project and has already finished protecting the area from Galle Fort to Mahamodara from erosion. This plan is carried out not only for protection but also to explore the potential of recreation and multi-use of coastline. The protection of the coast is also a natural process just like erosion. The best protection man can do is to just be patient. For example, if a tourist hotel is in the stage of being wiped off to the sea, at least a revetment should be laid to protect it.

Even if such protection is done, nature tries to recap what it has lost from another side of the beach. So it is better to allow nature to solve its problem. There are also some responsibilities man should fulfil. They should reduce excessive sand mining,. Reallocation of small houses is among the leading steps to stop coastal erosion.

The Coast Conservation Department in future should take measures to widen the coast, so that it could be usable without erosion. Sand is used to create Artificial Sand Nourishment. But the authorities will have to spend much money on that. It is said that CCD spends Rs.60,000 to lay revetment for one liner-metre. While it spend more money for laying revetments, no thought is made to nourish the beach by sand pumping and making artificial beaches as in China and the Netherlands.

Golden beaches boost tourism. This will in turn help in development.