Talk on “Use of Web tools for teaching: bogs, wikis, podcasting and other web 2.0 tools”

by Dr Hiran Amarasekera
Senior Lecturer and Head, Department of Forestry and Environment Science, University of Sri Jayewardenepura
The web is, and always has been, an exciting place for education in terms of the possibilities it offers for research and collaboration. Now, it is even more exciting, with the appearance and development of new tools which have become collectively known as Web 2.0. The purpose of this talk, is to provide an introduction to Web 2.0 to academics and researchers who are not too sure of what it is all about.
The aim of the talk is not to be comprehensive, which is impossible in a sense: there seems to be new tools appearing every day. It is, in fact, to encourage you to explore these things in teaching new generation of students.

Institute of Biology, and Department of Forestry and Environment Science, University of Sri Jayewardenepura organize this talk on 27 March 2007 at 2.30 pm at Forestry Auditorium, University of Sri Jayewardenepura, Nugegoda.


  • Introduction to eLearning
  • Introduction to new WWW (web 2.0)
  • Tools for developing and delivering online learning: Static and dynamic content web sites, Virtual Learning Environments, RSS feeds, Blogging, Photo Sharing, Podcasts, Webcasts, Video Blogging, Wikis, Social Bookmarking
  • Recommended web sites for lectures and students.

Poll to evaluate your knowledge on web 2.0

Before register, please take a moment to vote on web 2.0 sites, that you are familier with:


To register for this lecture, please follow this link to send us an email.
Register me for the lecture

Some terms you will hear at this talk


Blog – Short for web log, or online journal. It is a website that contains diary- type written material, links or photos being posted all the time, usually by one individual, on a personal basis
Some of our blogs:
Environmentlanka blog by Hiran Amaraskera
Blog of Forestry students at University of Sri Jayewardnepuera
Research papers presented at Forestry and Enviornment symposium 2005

e-learning 2.0
– combines the use of tools and web services – such as blogs, wikis, and other social software (so called web 2.0 software) – to support the creation of learning communities.

Folksonomies (or social tags) – A mechanism to allow authors to highlight other similar content to a reader, using informal, keyword tags; particularly effective for sharing bookmarks.
Our social tags at

M-learning – learning distributed to mobile devices such as cell phones or PDAs.
Our mLearning site at studentlanka

Photo sharing – Share your photos with others online.
Our photosharing site at Flickr

Podcast – This is an audio recording that you can subscribe or download and listen to on a computer or an mp3 player. It takes its name from the iPod – but you don’t actually need an iPod to either make or listen to a podcast. There are lots of educational podcasts freely available.

RSS feeds – Usually taken to stand for Really Simple Syndication, RSS is what makes it possible to subscribe to podcasts and blogs. We use search engines to find informaiton. But, with RSS, we are training the information to find us.

VLE (Virtual learning environment) – software which allows teachers to track students’ progress, manage course content, and so on.

Web 2.0 – There’s some debate about exactly what it means! Until recently the world wide web has been seen pretty much as a static publishing medium, now it has become a participatory platform with blogs, wikis and other tools. Hence it is not not merely another way in publishig, but anyone can contribute to an ongoing “conversation” in which knowledge is both discovered and constructed as it goes on.

Wiki – A web page that can be edited in situ by anybody who has been granted access to it. This is a great tool for collaboration of information in teaching.

Ten best web sites for students and teachers


We have compiled a list of free blogging software, free educational podcasts and webcasts at Univeristy of berkeley, free open couseware at MIT, online books, opensource software and other useful links. Follow this link to access these ten best web sites for students and teachers.




Sinharaja Rain Forest Trail Map

Sinharaja Trail Map

A – Kudawa Conservation Centre
B – Jeep track from Kudawa Conservation Centre to Kudawa Research Station
C – Mulawella Peak
D – Kudawa Research Station
E – Gal Yen Yaya
F – Sinhagala Peak
G – Pitadeniya Conservation Centre
H – Pitadeniya Ticket Counter
I – Track from Mediripitiya to Pitadeniya Conservation Centre
J – Kohila Aramba
K – Kekuna Ella
L – Patan-oya Ella
M – Duwili Ella (Kosmulla)
N – Morningside Conservation Centre
O – Natural Pool
P – Duwili Ella (Morningside)

1 – Wathurawa- Mulawella
2 – From Kudawa Conservation Centre to Nawanda Tree
3 – From Sinhagala Trail to Gal Len Yaya
4 – Sinhagala trail from Kudawa
5 – Kohila Aamba Trail
6 – Kekuna Ella and Pata-oua Ella Trail
7 – Sinhagala Trail from Pitadeniya
8 – Duwili Ella Trail from Denuwakanda
9 – Duwili Ella Trail from MCC
10 – From Morningside to the natural pool
11 – Trail from Kosmulla via Duwili Ella to Siththara gal lena (cave)

sinharaja forest

Sinharaja Forest

Sinharaja Forest

Trail Map of Sinharaja     Travel Information
Singharaja Forest Reserve is the most famous rainforest of the country. This tropical rain forest is a living heritage. Bio diversity of the forest is very high and a large proportion of the flora in this forest is endemic to the country and some endemic to the Singharaja Forest itself. This is a very good place to see many endemic birds such as Ceylon Lorikeet, Layard’s parakeet, Jungle and Spur Fowl, Ceylon Wood Pigeon, Grey Hombill, Spotted wing Thrush, Rufous and Brown- capped Babbler, Ashy-headed Laughing Thrush, Ceylon Blue Magpie, White Headed Starling, Ceylon Hill Mynha, Legge’s Flowerpecker. The clear cut roads in to the jungle provide easy access to the forest. This important forest is a Man and Biosphere Forest reserve and it is considered as a World Heritage Site.

  1. IUCN Management Category  II (National Park), Biosphere Reserve, Natural World Heritage Site – Criteria ii, iv
  2. Geographical Location Situated in the south-west lowland wet zone of Sri Lanka, within Sabaragamuwa and Southern provinces. It is bounded on the north by the Napola Dola and Koskulana Ganga, on the south and south-west by the Maha Dola and Gin Ganga, on the west by the Kalukandawa Ela and Kudawa Ganga and on the east by an ancient footpath near Beverley Tea Estate and by the Denuwa Kanda. 6°21′-6°26’N, 80°21′-80°34’E

  3. Date and History of establishment Notified a national heritage wilderness area on 21 October 1988 (Gazette No. 528/14). Most of the area was originally declared a forest reserve on 3 May 1875 under the Waste Lands Ordinance and notified in the Ceylon Government Gazette No. 4046, dated 8 May 1875, while the rest was notified a proposed forest reserve in the early 20th century. Sinharaja Forest Reserve, comprising the existing and proposed forest reserves, was declared a biosphere reserve in April 1978, and inscribed on the World Heritage List in 1988.

  4. Area According to Gazette No. 528/14, the total area of the national heritage wilderness area is 18,899 acres and 12 perches (7,648.2ha). The area of the biosphere reserve and World Heritage site as cited in the respective nominations is 8,864ha, of which 6,092ha is forest reserve and 2,772ha is a proposed forest reserve.

  5. Land tenure State

  6. Altitude Ranges from 300m to 1,170m (Hinipitigala Peak).

  7. Physical features This narrow strip of undulating terrain consists of a series of ridges and valleys. It is drained by an intricate network of streams, which flow into the Gin Ganga on the southern boundary and Kalu Ganga, via the Napola Dola, Koskulana Ganga and Kudawa Ganga, on the northern boundary. The reserve lies within the transition zone of two important rock types characteristic of Sri Lanka. The south-western group consists of metasediments, charnokites and scapolite-bearing calc-granulites, while the highland group comprises khondalites of metamorphosed sediments and charnokites (Cooray, 1978). Mostsignificant is the presence of the Sinharaja Basic Zone, consisting of hornblende, pyriclasts, basic charnokites, pyroxene amphibolites and scapolite-bearing calc-granulites and blended with small amounts of quartzites, garnet-biotite gneisses and intermediate charnokites (Hapuarachi et al., 1964). This zone coincides with an aeromagnetic anomaly, which has probably contributed to the desilication process responsible for the gem fields in the area (Katz, 1972; Munasinghe and Dissanayake, 1980). Soils, which largely belong to the red-yellow podzolic group, are well-drained and show very little accumulation of organic matter. This characteristic is attributed to a combination of favourable climatic conditions, a diverse soil microflora effecting rapid breakdown of organic matter into constituent nutrients, and accelerated uptake and recycling of nutrients by the trees. Clear-felling of the forest, where most of the nutrients are locked up, therefore renders the soil impoverished of essential nutrients and incapable of supporting sustained commercial forestry or agriculture (Forest Department, 1986). Information on soil profiles and soil microfungi are given in Zoysa and Raheem (1987).

  8. Climate Based on meteorological records gathered from in and around Sinharaja over the last 60 years, annual rainfall has ranged from 3614mm to 5006mm and temperatures from 19°C to 34°C (Zoysa and Raheem, 1987). Most precipitation emanates from the south-west monsoons during May-July and the north-east monsoons during November-January. Conditions are dry in February.

  9. Vegetationspan style=”font-size: small;”>Two main types of forest can be recognised. Remnants of Dipterocarpus forest occur in valleys and on their lower slopes, with hora D. zeylanicus and bu hora D. hispidus present in almost pure stands. Secondary forest and scrub occur where the original forest cover has been removed by shifting cultivation and in other places the forest has been replaced by rubber and tea plantations (Rosayro, 1954). Mesua-Doona (Shorea) forest, the climax vegetation over most of the reserve, covers the middle and upper slopes above 500m (Rosayro, 1942) or above 335m as suggested by Gunatilleke and Gunatilleke (1985). Garcinia hermonii followed by Xylopia championii invariably dominate the understorey tree stratum, a range of species dominate the subcanopy and na Mesua nagassarium usually predominates in the canopy layer (Gunatilleke and Gunatilleke, 1985). Details about the structure and composition of the vegetation are summarised by Zoysa and Raheem (1987). Of Sri Lanka’s 830 endemic species, 217 trees and woody climbers are found in the lowland wet zone (Peeris, 1975). Of these, 139 (64%) have been recorded in Sinharaja (Gunatilleke and Gunatilleke, 1985), 16 of which are considered to be rare (Gunatilleke and Gunatilleke, 1981). Other rare endemics are the palm Loxococcus rupicola (R) and Atalantia rotundifolia, the latter being restricted to Sinhagala at 742m. Of 211 recorded species of trees and woody climbers, 40% have low population densities (less than or 10 or fewer individuals per 25ha) and 43% have restricted distributions, rendering them vulnerable to further encroachments into the reserve (Gunatilleke and Gunatilleke, 1981). A variety of plants of known benefit to man are present, of which palm kitul Caryota urens (for jaggery, a sugar substitute), wewal Calamus sp. (for cane), cardamom Elattaria ensal (as spice), Shorea sp. (for flour), dun Shorea sp. (for varnish and incense) and weniwal Coscinium fenestratum (for medicinal purposes) are used intensively by villagers. A list of 202 plants, together with their endemicity and uses is given in the draft conservation plan (Forest Department, 1985).

  10. Fauna An early account of the fauna is given by Baker (1937). Preliminary lists of the fauna (viz. mammals, birds, reptiles, amphibians, fishes and butterflies) have been compiled (March for Conservation, 1985) and are included in the draft conservation plan (ForestDepartment, 1985). Endemism is high, particularly for birds with 19 (95%) of 20 species endemic to Sri Lanka present. Endemism among mammals and butterflies is also greater than 50%. Threatened mammals are leopard Panthera pardus and Indian elephant Elephas maximus (E). The endemic purple-faced langur Presbytis senex is present. Birds considered to be endangered or rare (Hoffmann, 1984) are Sri Lanka wood pigeon Columba torringtoni, green-billed coucal Centropus chlororhynchus, Sri Lanka white-headed starling Sturnus senex, Sri Lanka blue magpie Cissa ornata, and ashy-headed babbler Garrulax cinereifrons, all of which are endemic, and red-faced malkoha Phaenicophaeus pyrrhocephalus. Of interest is the presence of Sri Lanka broad-billed roller Eurystomus orientalis irisi (I), sightings of which have decreased markedly in the last five years (Zoysa and Raheem, 1987). Of the reptiles and amphibia, python Python molurus is vulnerable and a number of endemic species are likely to be threatened. Noteworthy species include Calotes liolepis, the rarest of all Agamids on the island, the rare rough-nose horned lizard Ceratophora aspera, restricted to part of Sri Lanka’s wet zone, and Ramella palmata, a rare endemic microhylid (Zoysa and Raheem, 1987). Threatened freshwater fish are combtail Belontia signata (R), smooth-breasted snakehead Channa orientalis (R), black ruby barb Barbus nigrofasciatus (V), cherry barb Barbus titeya (V) and red-tail goby Sicydium halei (V), the conservation status of which is considered in Evans (1981). Of the 21 species of endemic butterfly, Sri Lanka rose Atrophaneura jophon is vulnerable (Collins and Morris, 1985). Sri Lankan five-bar sword Graphium antiphates ceylonicus, which is considered to be very rare, is not uncommon in Sinharaja at certain times of the year (J.N. Banks, pers. comm., 1986). Zoysa and Raheem (1987) comprehensively summarise what is known about the fauna.

  11. Cultural Heritage The Sinharaja region has long featured in the legends and lore of the people of Sri Lanka. Its name, literally meaning lion (sinha) king (raja), perhaps refers to the original ‘king-sized or royal forest of the Sinhalese’, a people of the legendary ‘lion-race’ of Sri Lanka (Hoffmann, 1979), or to the home of a legendary lion of Sri Lanka.

  12. Local and Human Population There are two villages within the south-west of the reserve, namely Warukandeniya and Kolonthotuwa, and about 52 families live in the north-western sector. At least 20 other settlements occur on the periphery, an unknown number of which have been illegally established on state land without approval from the relevant authorities. The total population is in excess of 5,000 people. Some land adjacent to the reserve is under private ownership, including small tea and rubber plantations. The extent to which local people are economically dependent on rain forest resources is variable but about 8% of households might be completely dependent (Silva, 1985).

  13. Visitors and Visitor Facilities Visitors are low in number and mostly naturalists. Entry is by permit, obtainable from the Forest Department in Colombo. There are nature trails to the peaks of Moulawella and Sinhagala. Guidebooks to the Moulawella Trail and to the secondary vegetation have recently been prepared (Gunatilleke et al., 1987a, 1987b). Some accommodation is available with the Forest Department near the reserve entrance at Kudawa. Further facilities are planned.

  14. Scientific research an Facilities Among the earliest studies are those of Baker (1937, 1938). Rosayro (1954, 1959), Andrews (1961) and Merritt and Ranatunga (1959) assessed the area’s potential for selective logging, based on aerial and ground surveys. Gunatilleke and Gunatilleke (1980, 1981, 1985) examined the floristic composition and phytosociology of woody vegetation and assessed its conservation value. Research on theendemic fauna has been undertaken by WWF/IUCN (Project 1733) and March for Conservation (Karunaratne et al., 1981). Conflicts over the local use of forest resources have been examined by McDermott (1985, 1986) and Silva (1985). An annotated vegetation/land-use map (1:40,000) of the reserve has been produced by the Forest Department (n.d.). The Natural Resources Energy and Science Authority of Sri Lanka has provided a field research station in the reserve. The Forest Department building at Kudawa, outside the reserve, is used by scientists and visitors.

  15. Covservation Value Sinharaja is the last extensive primary lowland tropical rain forest in Sri Lanka. It holds a large number of endemic species of plants and animals, and a variety of plants of known benefit to man. Sinharaja Forest Reserve is the last viable remnant of Sri Lanka’s tropical lowland rain forest; over 60% of the trees are endemic and many of these are rare; and there are 21 endemic bird species, and a number of rare insects, reptiles and amphibians (IUCN Technical Evaluation).

  16. Conservation Management Sinharaja is administered by the Forest Department under the Ministry of Lands and Land Development. Recognising the need for maximum possible protection, it has recently been declared as a national heritage wilderness area under the National Heritage Wilderness Areas Act. Any excision to such an area is permissible only with the concurrence of parliament and the President of the country. The site is also partially protected under the provisions of the Forest Ordinance. Sinharaja was first recognised in 1936 as being “the only considerable patch of virgin tropical rain-forest in the island” (Baker, 1937). Owing to its inaccessibility and steep, hilly terrain, the reserve remained untouched until 1968 when a government directive was issued to extract timber for the plywood sawmill and chipwood complex established at Kosgama. From 1971 until 1977, when logging was banned, largely due to public pressure with the Wildlife and Nature Protection Society playing a leading role (see Hoffmann, 1972, 1977), about 1,400ha of forest in the western sector were selectively logged (Gunatilleke, 1978; Forest Department, 1986). Presently, the reserve has 6,500-7,000ha of unlogged forest. Since 1977, the Forest Department has given high priority to protecting the reserve and in 1978 began planting Pinus caribaea along the periphery to establish a live boundary. More recently, betelnut palm Areca catechu has been used for this purpose (Zoysa and Raheem, 1987).

  17. A conservation plan has been officially approved (Forest Department, 1986), implementation of which is being carried out under a cooperative agreement between IUCN and the Sri Lankan government, with additional funding from the Norwegian government (Hails, 1989). In order to ensure the strict protection of the reserve for scientific and aesthetic reasons, a scheme of zonation and management is proposed for areas outside the reserve. The creation and propagation of essential forest products, for sustained utilisation, in areas outside the reserve is intended to meet local needs and thereby eliminate former dependence on resources within the reserve. Alternative strategies are either to establish a 3.2km-wide buffer zone round the reserve or to enlarge the area protected to about 47,380ha, with the reserve forming a strictly protected core area and surrounding areas set aside as buffers for various uses. The only resource which may still be legally collected, under permit, is kitul (McDermott, 1988). The preferred strategy has been to freeze resource use within the reserve at 1985 levels (when the conservation plan was prepared) and gradually eliminate futureresource dependency on the reserve by relocating villages to areas outside the reserve (Ishwaran and Erdelen, 1990).

  18. Management Costraints Of the many constraints to the protection of Sinharaja, socio-economic ones relating to the people and organisations in the immediate vicinity of the reserve are perhaps among the most important. Encroaching cultivations are probably the biggest problem, particularly along the southern boundary (McDermot, 1985). Contractors open up routes to facilitate logging operations and, although no felling is permitted within 1.6km of the reserve boundary, this may render the reserve more accessible to illicit timber operations. Planting of Honduran mahogany Swietenia macrophylla along abandoned logging trails as an enrichment species may lead to displacement of natural species, especially as it is a prolific seed producer (Zoysa and Raheem, 1987). Alleged malpractices by the State Timber Corporation are a source of concern for the Forest Department. Private land owners along the periphery perhaps make illegitimate use of timber resources within the reserve: having felled all merchantable timber on their own land, they continue to request permits for timber (Hathurusinghe, 1985). The most important forest produce is firewood, significant quantities of which are used in the production of jaggery (McDermot, 1985; Silva, 1985). The traditional use of minor forest products, most important of which are kitul for jaggery and wewal or cane for weaving baskets, is now restricted to forest surrounding the reserve. Illicit gem mining was considered to be a serious problem in eastern parts of the reserve. It is organised mostly by wealthy merchants from outside the Sinharaja region and needs to be stopped. The lack of a uniform land-use policy and the multiplicity of governmental and semi-governmental agencies involved in land-use planning in Sri Lanka are the major administrative constraints in evolving a suitable protection plan for Sinharaja. For the moment, transactions related to lands surrounding the reserve are suspended under presidential order until such time as the conservation plan for the reserve is ready for implementation (Forest Department, 1986).

  19. Local Address Range Forest Officer, Range Forest Office, Kudawa, Weddagala (An assistant conservator of forests will eventually be responsible for implementing the conservation plan.)

    Trail Map of Sinharaja
    Compiled By L.A.M.C.Amarasekara
    Forestry and environment socitey, University of Sri Jayewardenepura

Sustainable Agricultural Practices

Dr. P.B. Dharmasena
Field Crops Research and Development Institute, Mahailluppallama

Sri Lanka is still and will be for near future considered as a country dependant mainly upon agriculture including plantation sector. Challenges posed by external factors due to globalization and open economic policies have directed the country’s agriculture to move away from the self reliance. Competitive export and import opportunities among countries have led to maintain the standard levels of quality and steady levels of production at a lower price in all commodities. This situation demands a firm and perfect policy for country’s agriculture. Further, present agriculture does not show any indication of sustainability as it has ignored the centuries old wisdom of traditional agriculture. In developing a strategic mechanism to promote an alternative to present agriculture, cognizance must be taken from deep rooted customs and traditions and the time tested agricultural practices to assure the sustainability in the agricultural sector. Farmers’ dependency mentality evolved due to modern agriculture and the government policies dealt with agriculture from time to time should gradually be removed by developing self confidence, self motivation and empowerment.

Most critical issue at present is that the agriculture does not bring a consistent economic gain to the farmer. Import export policies do not respond effectively to maintain profitability of farming. Farming without adequate concern on conservation of natural resources such as soil and water and environmental protection has led to deterioration of the agricultural resource base in the country and pollution of the environment. Government has not paid adequate attention to provide farmers with input and marketing facilities in time. Land resource is utilized for various purposes including agriculture with out considering its suitability, capability and vulnerability to degradation. Farmers are not much aware of the current trends in agriculture, marketing and technologies.

Policy Aspects

Need is felt for urgent attention to formulate a firm policy to implement sustainable agricultural production program in the country. In policy statements on various sectors of the agriculture following aspects should be included to assure conservation and efficient utilization of soil and water resources.

In irrigated agriculture water losses from reservoirs and canals should be minimized, efficient field water management has to be promoted for increasing the water productivity through crop diversification and with new water saving techniques. In rain fed agriculture the unirrigable land mass of the country should be developed on watershed basis with proper soil and water conservation techniques, put into most suitable land use forms such as agro-forests, perennial orchards, field crop farms, mixed timber plantations, pasture lands etc. State resources should be mobilized to make these lands productive with sustainable rain fed agriculture to benefit farmers on short, medium and long run.
Organic farming should be encouraged to reduce adverse effects of agro-chemicals and inorganic fertilizer on environment and human health by expanding the organic farming sector, creating awareness in general public for consumption of organic products, generating new technology and certifying products, processing and packaging to earn foreign exchange and gain high price to the farmers. Integrated farming should be introduced to farmers for optimum use of their resources, year round steady income and effective use of residues. The policy on integrated farming towards sustainable agriculture should be to improve village level productive farming, discourage artificial products and chemical use, familiarize livestock farming and encourage cottage industries to capture foreign and local market with traditional products.

Sustainable agriculture policy should stress the importance of conserving natural resources (land, water, forest, atmosphere etc.), while utilizing them effectively for agricultural production. All land users for agriculture should be encouraged for sustainable use of natural resources by awareness creation, making resources conservation compulsory, generation of improved technologies, safe and efficient management of rainwater, river, tank and groundwater.

Agriculture should be mechanized in all possible ways to reduce the cost of production and improve the quality of produce but with no harmful effects on natural resources such as wind and water erosion, increased water and soil nutrient losses, air pollution etc.

National policy on agriculture should emphasize the use of indigenous knowledge in agriculture, which ensures preserving and utilizing traditional crops and varieties, resources conservation practices, medicinal plants, cottage industries and agricultural heritage of the country.

Strategies to Achieve Sustainability in Agriculture

In implementing what is spelled out in a policy various strategies need to be identified. Following activities need much attention to achieve sustainable agriculture production in Sri Lanka with special reference to soil and water conservation.

Lands potentially suitable for agriculture should be given priority for agricultural production to assure the land resource availability for future expansion of agriculture. Primary and secondary forest lands should not be exploited for any purpose other than development of forest vegetations. Decision makers of agricultural production planning should not consider only the national production requirement but also the sustainable production levels of resources including farmers. Thus, food production expectations should aim at national food security, but not always at reducing outflow of foreign exchange for food imports.

Increasing agricultural productivity should not jeopardize the land, water and other resources of the country. Since many ministries bear the mandate of conserving natural resources there is a necessity to establish a national advisory board for conservation of natural resources independent of political authority.

A national development plan for agriculture has to be prepared wherein integrated approach of agriculture, livestock and small agro-based industries is promoted. Any agriculture related activity implemented in the country should be a part of the national agriculture development plan. Committees should be established at provincial, district, divisional and village level to plan and implement the agricultural production program. Farmers should be protected from adverse effects of free trade policies and globalization.

Reorientation of Research Agenda

In identifying areas for research under the theme of alternative agriculture for self reliance most essential knowledge urgently needed can be obtained by answering following ten research questions.

1. How can the negative impacts of globalization and trade liberalization be managed locally to achieve sustainability in agricultural production?

2. What land and water resources are available in quantity and quality in different parts of the country?

3. How they could be developed and allocated for different purposes among competing interests?

4. What governance framework and institutional mechanisms (policy, legal and organizational frameworks) are needed to create an environment for cost-effective interventions of sustainable agriculture?

5. What is the relationship between poverty and environmental degradation?

6. How poverty can be alleviated through sustainable agriculture?

7. How can the impacts (environmental, social and economic) of land use changes be assessed?

8. What combinations of technological and management strategies are needed to assure the utilization of natural resources effectively, efficiently and equitably for agriculture to alleviate poverty and enhance environmental security?

9. How a community can feel and realize an improving process of sustainability?

10. What Decision Support Information Systems are needed to empower the stake holders in implementing sustainable agricultural development programs?

Reorientation of agricultural research agenda from crop based to resource productivity based is essential to achieve sustainability. Promotion of endemic fruits, vegetables and medicinal products for both local consumption and foreign markets can be initiated through research. Knowledge on conservation of natural resources at present is dispersed and available in various institutions. Gaps need to be identified where further studies are needed and organized by networking them so that any would have the access for utilization.

Theme talk made at the Tenth Annual Forestry and Environment Symposium held at Kabool Lanka International Training Center, Thulhiriya on 2nd and 3rd 2005 organized by Department of Forestry and Environmental Science, University of Sri Jayewardenepura, Sri Lanka

Pollution Control and Waste Management

Dr. W.L. Sumathipala
Senior Lecturer
The Open University of Sri Lanka,
Director, National Ozone Unit, Ministry of Environment
The magnitude of degradation of the environment increased tremendously with the industrial revolution which started in 1850s. Even prior to the industrial revolution, pollution due to human activities existed but in a reduced amount. Those days the assimilation capacity of the environment was greater than the release of pollutants in to the environment. Large volumes of wastes were released in to the environment with the development of machine-based industries. Then the assimilation capacity of the environment became lower than the rate of waste generation. As a result wastes accumulated in the environment giving rise to problems, which threatens the life existence on planet Earth.

In general, pollution can be considered in terms of Air Pollution, Water Pollution and Land Pollution. Scientists are also considering some specific types of pollution such as pollution due to Noise, radiation and high temperature.

Since there are no boundaries in the atmosphere air is not limited to a place, region or to a country. Therefore air pollution produced in some parts of the world can cause problems in another country in the world. Therefore air pollution should be considered as a major problem where international efforts are needed to address the atmospheric problems. Further it is considered to be a serious problem as it affects the human health worldwide. All the terrestrial life forms are exchanging gases with the atmosphere. Therefore there is a danger of inhaling/absorbing what ever the pollutants available in the atmosphere because they do not have a filtering mechanism. On the other hand the pollutants released in to the atmosphere gets diluted and the possibility of collecting or treating such pollution is impossible. Therefore preventing, controlling or treating these substances before releasing them in to the atmosphere is very important. The atmospheric lifetime of some pollutants/chemicals is very high and they cause global environmental problems such as Ozone Layer depletion.

The main sources for air pollution are burning fossil fuels for energy generation & transportation, biomass burning and industrial emissions. The sources of air pollution give rise to gases, mixtures of fine particles or both. Most common gases generated from burning fossil fuels are CO2, CO, Oxides of Nitrogen, Oxides of Sulfur and unburned hydrocarbons. Pollution due to biomass burning for cooking is very common in the Asian region. This will generate unburned hydrocarbons due to incomplete burning processes, mixture of oxides of carbon, nitrogen & sulfur and particulate matter. Industrial emissions are responsible for most hazardous chemicals such as fluorinated carbons, PFCs, SF6, etc.

Considering the difficulty of treating these gasses after releasing in to the atmosphere it is important to either control or treat the emission before releasing to the atmosphere. In the industrial sector, controlling the emission of air pollutants can be achieved through changing the method of plant operation, changing the input or raw materials used in the process, adopting cleaner production methods or treating the pollutants prior to release. Gaseous pollutants can be removed from their gaseous environment to either a liquid or a solid surface, where they will be preferentially retained, or where they react to form a non polluted species. There are processes with various methods used for collecting gases with high concentration such as absorption in to a liquid or solid or adsorption on to a solid surface. These are occurring either with or with out reaction. Pollutants generated due to incomplete combustion can be removed through complete combustion converting them into CO2 and water. This can be achieved in a combustion chamber providing sufficient air in the presence of a catalyst. In order to prevent the release of particulate matter to the atmosphere, settling chambers, gravity separators, cyclone dust collectors, filters, wet scrubbers and electro statistic precipitators can be utilized.

Emission of radioactive particles is possible due to the development of energy generation through nuclear power plants. Since these materials cannot be detected by human senses such as taste or smell and even a very minute quantity is lethal, there has to be stringent regulations utmost in operating these plants and handling waste. These should operate on hundred percent accident free environments. In addition, installation of multiple barriers, real time monitoring and error free safeguard systems are very important for these facilities.

Indoor air quality is very important, mainly because people remain indoors in excess of 90% of their lifetime. Common indoor pollutants are Paints, Varnish, polish, household polymers, fuel wood burning, burning incense sticks and mosquito coils. Houses or buildings with less ventilation are vulnerable for indoor air pollution resulting in nausea, vomiting, dizziness and respiratory diseases. As a solution, Architects can design well-ventilated buildings with more air circulation.

Substances such as CFC, Halons, CTC, HCFC are depleting the Ozone Layer that protects human from the Sun’s dangerous UV radiation. Increase of Greenhouse gases such as Fluorinated Carbons, Methane, and Nitrous Oxides in the atmosphere is making the earth atmosphere warmer resulting in climate change and sea level rise. Global commitment is essential in order to control such global environmental problems. Montreal Protocol and Kyoto Protocols are major global agreements to take action in order to control these two major environmental problems.

Water is a basic requirement for sustaining life. Out of the total volume of available water in the planet, less than 1% is suitable for human consumption. This limited resource is further reduced due to human activities, which make it unusable. Main sources of water pollution are release of industrial waste, dumping solid waste, sewage, human waste including faecal matter, sediment run off due to soil erosion etc. As a result of such activities, concentration of dissolved carbons, heavy metals, biohazards such as bacteria and virus and other nutrients will increase in the water sources resulting in loss of biodiversity and making the water unsafe for consumption. Several methods have been developed for water treatment once it is polluted. Biological treatment, chemical coagulation and filtration, carbon adsorption, chemical oxidation, ion exchange, electrodialysis, reverse osmosis, air stripping are some of them. Water bodies are also being polluted due to discharge of sewage from watercrafts and oil spilling around the world. Designing holding tanks for receiving and storing sewage until they can be unloaded on the shore is one controlling method. Large vessels can be equipped with biological treatment plants. Leaks from offshore drilling and accidental oil spills are possible resulting in threat to water creatures and large-scale killing of sea birds. Surrounding the oil slick with a mechanical barrier until it can be removed, collecting the oil by mechanical means such as suction pumping or absorption by a suitable material and dispersing the slick with chemicals are methods practiced today.
Environmental problems due to solid waste are a growing problem in Sri Lanka and it is a major problem in many of the developing countries. Current rate of waste collection by the local authorities in Sri Lanka is estimated to be about 2,500 tones per day. Rate of waste generation depends on a number of factors such as socio economic conditions, public attitude towards reuse and recycling of waste and geographical and physical factors. Due to the improvement of technology, a tremendous increase in non-degradable packaging materials such as plastic, polythene, metals and glass can be seen. Solid wastes are generated from domestic, institutional, market, medical, commercial, industrial and garden sources. Industries such as food, paper, cardboard, rubber, and leather are good sources of organic waste. A greater portion of commercial and domestic waste are organic and biodegradable. The major problem in relation to solid waste is uncontrolled disposal of wastes.

Toxic and hazardous wastes are generated mainly from industrial and medical sectors. The extent of land pollution increases due to unorganized solid waste disposal practices. Developing facilities for safe disposal and management of solid waste should be a high priority in society. With the rapid development, population growth and urbanization, solid waste has increased and therefore it is essential to manage solid waste. There is also a serious threat of utilizing Sri Lanka as a hazardous waste dumping site.

According to the estimates the local authorities collect only a part of the waste generated. Disposing wastes in the home gardens are common in rural areas due to lack of collecting system or facilities. At present waste disposal is mainly in open dumps, which are unsanitary. Most of these areas are low laying marshy lands and abandoned paddy fields. As a result leachate, emission of gases, odors, fire and loss of aesthetic beauty are possible. As an alternative to open dumping, sanitary land filling has to be introduced. Proper planning is essential to minimize the side effects. Separation of solid waste at the point of generation is essential and thereafter different categories can be treated separately. Biodegradable materials have to be composed and used as organic manure as far as possible. Avenues for collecting recyclable materials and recycling should be promoted. The final waste that is not possible for recycle has to be dump in a sanitary landfill. Incineration is another option but the capital cost is very high and therefore it may not be suitable for a developing country. At least several small-scale incinerators are essential to destroy toxic and hazardous waste.

Noise pollution has a very close relationship with occupational safety. In most cases industries are responsible for high noise pollution. Recent studies show that there is direct relationship with high levels of noise and mental health. Noise management can be achieved at the point of its origin and along the noise pathway and at the point of reception. There are several noise management techniques available at present. Shock absorbing techniques, use of non metal parts to reduce the noise generated, use of acoustic guards, installing machinery on adequate mountings, locating machinery away from the residential areas are some of precautionary methods.

In most of the industries a large amount of heat is generated and released in to the atmosphere. This problem of thermal pollution can be alleviated by using artificial cooling ponds or cooling towers. Where possible this high temperature can be utilized for useful work such as generation of electricity.

In order to control pollution, proper and appropriate legislation, emission and effluent standards for industries are essential. Awareness creation among the general public and making the man more environment friendly is an over all approach for environment protection.

Theme talk made at the Tenth Annual Forestry and Environment Symposium held at Kabool Lanka International Training Center, Thulhiriya on 2nd and 3rd 2005 organized by Department of Forestry and Environmental Science, University of Sri Jayewardenepura, Sri Lanka 

Recent Trends in the Forestry Sector of Sri Lanka

Mr H M Bandaratillake
Director, Forest Resources Management Project
Ministry of Environment & Natural Resources
Former Conservator, Forest Department, Sri Lanka

Abstract of the theme talk presented at the tenth Forestry and Environment Symposium of the Department of Forestry and Environmental Science, University of Sri Jayewardenpura, Sri Lanka on 2-3 December 2005

The forest cover in Sri Lanka has been continuously declining during the last several decades. The forest cover which was around 44% of the land area in 1956 had declined to 23.9% in 1992 and 22% at present. It has been widely accepted that this rate of deforestation has caused one of the main environmental and social problems in the country. Although, successive governments have taken many steps to conserve forests and to introduce laws and regulations to control deforestation, the problem was aggravating from year to year without effective solutions, mainly due to the conflicting demands placed on forest resources.

In view of this situation, the National Forest Policy was revised and Forestry Sector Master Plan (FSMP) was formulated and approved by the government in 1995. The Forestry Sector Master Plan (FSMP) which was based on the National Forest Policy, provides the framework for developing partnerships with non state sector for promoting community and private sector participation in forest conservation and development. FSMP also provide a guiding framework to introduce new policies and to carryout legislative, administrative and institutional reforms required.

The Forest Resources Management Project (FRMP) which is scheduled to implement during 2001- 2007 is the first implementation programme of the FSMP. The overall objective of the FRMP is to establish and operationalise participatory sustainable forest resources management for increasing forest protection and production. With the implementation of FRMP, number of new strategies and programmes have been introduced to the forestry sector in order to achieve the objectives of sustainable forest management. Some of these strategies include; private sector re-forestation and management, woodlot development, establishment of Permanent Forest Estate, Re-organisation of the Forest Department, Amendments to the Forest Ordinance, Private sector harvesting of forest plantation and development of nature tourism etc,. Legal provisions including mechanisms for benefit sharing have been provided to facilitate the effective implementation of these programmes.

CODE OF ETHICS for Research on Biological Diversity involving Access to Genetic Resources of Sri Lanka

Document published by Biodiversity Secretariat
Ministry of Environment and Natural Resources
82, Rajamalwatta Road,
Battaramulla, Sri Lanka


Sri Lanka is an island nation, which has a high level of biological diversity and a high percentage of endemic fauna and flora.

The Convention on Biological Diversity, which Sri Lanka and the vast majority of the nations of the world have ratified, has as two of its three objectives: (a) the conservation of biological diversity and (b) the fair and equitable sharing of the benefits arising out of the utilization of genetic resources.

In regard to the provision for providing access to genetic resources and sharing of benefits, the Convention on Biological Diversity, recognizing that States have sovereign rights over their biological resources (Art. 5), sets out inter alia that:

(a) Each State shall endeavour to create conditions to facilitate access to genetic resources for environmentally sound uses by other States; and access where granted shall be on mutually agreed terms (Art. 15,2 & 4)

(b) Access to genetic resources shall be subject to prior informed consent of the Contracting Party providing such resources, unless otherwise determined by that Party (Art. 15, 5)

(c) Each Contracting Party shall endeavour to develop and carry out scientific research based on genetic resources provided by other contracting parties, with the full participation of, and where possible in, such Contracting Parties (Art. 15, 6)

(d) Each Contracting Party shall take legislative, administrative or policy measures, as appropriate, with the aim of sharing in a fair and equitable way the results of research and development and the benefits arising from the commercial and other utilization of genetic resources with the Contracting Party providing such resources; such sharing shall be on mutually agreed terms (Art. 15, 7)

(e) Each Contracting Party shall take legislative, administrative or policy measures, as appropriate, with the aim that Contracting Parties, in particular those that are developing countries, which provide genetic resources are provided access to and transfer of technology which makes use of those resources, on mutually agreed terms (Art. 16, 3)

The Ministry in charge of the subject of environment holds the national responsibility for ensuring that the provisions of the Convention on Biological Diversity are adhered to by Sri Lanka as a Party to the Convention.


Research on biological diversity means research on the variability among living organisms as well as research on any of the components of biological diversity, which components shall include any active or dormant stage or life form, or any genetic material thereof, of an entity characterized as living, including plants, bacteria, algae, fungi, phytoplasmas, mycoplasmas, mycoplasma-like entities, protozoa, vertebrate and invertebrate fauna, as well as entities such as viruses, viroids, plasmids, phages, or any living entity related thereto whether natural or modified, as well as metabolites and other extracts of organisms to be used for research and development purposes.

Genetic material means any material of plant, animal, microbial or other origin containing functional units of heredity.


Any person or institution (hereinafter referred to as the researcher) engaged in or proposing to engage in research on the biological diversity of Sri Lanka that will involve the transfer out of the country of genetic material or metabolites and other extracts of organisms shall conform to the following requirements:

(1) Research on the biological diversity of Sri Lanka shall, as far as possible, be carried out in Sri Lanka, and by Sri Lankans or with the active participation of Sri Lankans.

(2) The researcher shall inform the Biodiversity Secretariat of the Ministry in charge of the subject of environment of the nature of the proposed research, and specifically (a) whether foreign nationals or foreign institutions will be involved and if so the nature and extent of such involvement, and (b) full details of the genetic material or metabolites or other extracts of organisms that will be sent out of the country. In either case the purpose must be disclosed fully; failure to do so will be tantamount to a breach of this code.

(3) Having regard to the facts as stated by the researcher, if the Biodiversity Secretariat is of the view that the research may give rise to discoveries leading to the development of commercial products or processes, an agreement in a form approved by the Ministry in charge of the subject of environment acting on the advice of the National Science Foundation and any other government institution shall be signed by the party abroad; such agreement shall inter alia embody clauses, as appropriate, for ensuring that Sri Lanka receives an equitable share of the benefits from the proposed research and development.

(4) If the Biodiversity Secretariat is of the view that the research would not give rise to discoveries leading to the development of commercial products or processes, the Biodiversity Secretariat shall inform the researcher that no agreement in the form specified in Section 3 need be signed.

(5) If, in the course of the research work, there are changes in the research protocol (from that reported earlier) or in the scope of foreign collaboration, details of such changes shall forthwith be reported to the Biodiversity Secretariat for a fresh determination of whether an agreement in terms of Section 3 has to be signed, or, if an agreement has already been signed, whether any amendments to the agreement would have to be made.

(6) This Code does not obviate the requirements under existing laws, rules and regulations, of the researcher obtaining the approval of the appropriate institutions for carrying out the proposed research; using any particular site; collecting biological material; or exporting genetic material, metabolites or other extracts of organisms.

(7) Notwithstanding the provisions of Articles 3,4 and 5 of this Code, in cases where foreign nationals and/or institutions are involved in research on biodiversity, the collaborating Sri Lankan researcher and/or the institution to which he is attached shall, where considered appropriate by the Ministry, through an agreement, exchange of letters, or other suitable instrument, with regard to the sharing of information, publication of results, lodging of samples and other relevant matters, ensure that Sri Lanka shares equitably in the results of the research.

(8) In the event of a breach of the provisions of this Code, the Ministry and/or any other government organization concerned reserves the right to cause a cessation activities and to “blacklist” the researcher concerned.

Ministry of Environment and Natural Resources (2004) Code of Ethics for Research on Biological Diversity involving Access to Genetic Resources, Biodiversity Secretariat, Ministry of Environment and Natural Resources, 6 pp. (ISBN 955-9120-30-1)
For details contact Mr. Gamini Gamage, Director, Biodiversity Secretariat, Ministry of Environment and Natural Resources, Battaramulla, Sri Lanka

Understanding Earthquakes and Tsunamis – part 2

Prof Dhammika A. Tantrigoda
Department of Physics, University of Sri Jayewardenepura
Nugegoda, Sri Lanka

Part 1>
Origin of Earthquakes

Richter Scale Magnitude of Earthquakes

Normally we would like to represent the magnitude or intensity of any process using a numerical value of a certain property related to the process on a suitable scale. For example, intensity of rainfall is expressed using height of the water collected in an open vessel kept in the rain (rain gauge) using a millimetre scale. Similarly the magnitude of an earthquake is expressed in terms of the amplitude of the ground motion. The scale on which this is expressed is called the Richter scale. In the original Richter scale, Richter defined the magnitude in terms of the maximum trace amplitude on a standard seismometer, sensitive equipment capable of monitoring vibrations of the earth, stationed at a distance of 100 km from the epicentre of the earthquake. The amplitude is expressed on a logarithmic scale. According to this scale an earthquake that shows amplitude of one metre on the standard seismometer has a magnitude 6. An earthquake that shows 1 km amplitude is designated to have a magnitude of 9 on this scale. There are practical problems in using this scale especially due to non-availability of seismic stations at an epicentral distance of 100 km of each and every earthquake. Therefore the original concept of Richter has been modified and new formula has been suggested. The new formula is capable of computing the magnitude of an earthquake monitored at any seismic station on the globe.

Energy Release

Methods of estimation of total energy released in an earthquake have been given by Richter, Guternburg and many others. It is somewhat difficult to appreciate the amount of energy released in an earthquake from the numerical magnitude alone. Comparison with other known processes that release energy would be of some help in this regard. A magnitude 1 earthquake is so weak that they can only be observed with sensitive instruments. Kinetic energy associated with such an earthquake is more or less equal to the kinetic energy of a vehicle weighing 15000 kg travelling at a speed of 130 km per hour. One ton of the explosive trinitrotoluene (TNT) releases about 4.2×109 (four thousand two hundred million) of Joules of energy. Energy released in the atomic bomb, which destroyed Hiroshima, is the same as that released by an explosion of eleven kilotons of TNT. This is equivalent to the energy released in a magnitude 5 earthquake. An earthquake of magnitude 9 releases about 1.6 x 1018 Joules. All lesser earthquakes numbering more than 500 000 per year only releases five per cent of the energy released by a magnitude 9 earthquake.

Generation of Tsunamis

When a very large earthquake occurs at a subduction zone, dislocation of the deformed and strained rock units cause the ocean bottom above the focus to rupture and collapse. This may result in either vertical upward or downward movement of the sea floor of an extensive region. Disturbed water mass will soon try to regain the equilibrium under gravity and in the process a train of waves are generated. This is somewhat analogous to a plucked string of a musical instrument trying to regain equilibrium by undergoing vibrations. The manner in which a disturbance caused by collapsing of sea floor generates a train of sea waves and the calculation of properties of the waves so generated can be carried out using classical fluid dynamics. The discussion, which follows, is based on qualitative treatment of the results obtained from such calculations.

Basics of Wave Propagation

We are all familiar with tiny water waves or ripples generated on the surface of a clear and calm pond as a result of dropping a pebble. We see that even though the ripples move outwards from the point at which pebble was dropped, small pieces of leaves floating on the water do not travel with the wave. Instead they oscillate up and down and to and fro around a fixed position. This clearly indicates that the medium (ie. water) does not travel when a wave is propagated through the medium. But the wave gives the capability to a piece of leaf to oscillate and this indicates what is been propagated is only the energy. In a wave we observe the repetition of a certain fundamental shape (figure 3). Length of this fundamental shape is known as the wavelength, speed at which this shape travels through the medium is called the wave speed and the time taken by the fundamental shape to travel its own distance is called the period of the wave. It is interesting to see how water particles (the medium) oscillate when a water wave is propagated. Contrary to what is stated in many elementary physics textbooks including those we use in our own schools, oscillations of water waves are not confined to the vertical direction. If the oscillations are confined to the vertical direction, then water should have stretched vertically at crests and compressed at troughs of the wave. We know very well that water does not have sufficient elastic properties to sustain such deformations. Therefore when a crest is formed water from the neighbouring region will flow in the horizontal direction to compensate for the amount of water that has gone up resulting in a trough in that region. So the oscillations are taking place in the vertical as well as horizontal directions. Very often horizontal component is more pronounced compared to the vertical component.

figure 3

Speed of Tsunami Waves

A sudden vertical disturbance of a water column generates a very large number of waves (pulses to be precise) with different wavelengths and they normally travel with different speeds and have different periods. All the waves that have wavelengths greater than six times the depths of the water layer travels with the same speed. This speed is equal to the square root of the product of acceleration due to gravity and the depth. According to this formula tsunami waves travelling in region of 4 km water depth has a speed of 200 meters per second or 720 km per hour. This value is comparable with the speed of a commercial jet aircraft. When tsunami waves reach the edge of the continental shelf their velocity reduces to about 45 metres per second and further reduces to about 10 metres per second when reaches the show. As a result of progressive reduction of speed when climbing the continental shelf tsunami waves acquire large amplitudes. Lower speed in the front part and higher speed in the rear part of the wave will result in bunching up water over a narrow region forming a tall wall of water near the shore.

Energy Propagation

Tsunamis are quite different to the water waves generated by the wind that we are very much familiar with. Tsunami waves have very long wavelengths, which are generally of the order 100 km to 200 km where as the wavelengths of waves generated by winds rarely exceeds a few tens of metres. In waves generated by winds the surface of the water mostly takes part in oscillations and the energy of the wave is almost limited to the surface. In tsunami waves the whole water column from the surface to the bottom of the sea takes part in oscillations and the energy is distributed in the whole water column. When it is passing through a region of the deep ocean its amplitude becomes very small as the total energy of the wave is now shared by a water column, which may be five to six kilometres deep. This is the reason as to why in the deep ocean tsunamis have amplitudes of less than one metre and are not detected by ships passing by. When a tsunami reaches a region of shallow water its energy is distributed in a small column of water and therefore should have higher amplitude to have the same amount of energy it had when passing through a deep region (tsunami waves loose very little energy when travelling through the deep ocean).

Main Phases of Tsunami Waves

phases of tsunami waves
Physicists and mathematicians have extensively studied water waves including tsunamis. It has been shown that a tsunami wave has two main phases in general as shown in figure 4. First phase is part of the wave in-between A and B in Figure 4 and this is known as Jeffery phase, in memory of one of the mathematicians who contributed to the better understanding of propagation of tsunamis. Rest of the wave is known as the oscillatory phase. It is useful to note that the Jeffery phase is only a sort of a crest of a wave and it does not have a trough. Actual size of the Jeffery phase depends on the nature of the initial disturbance of the water caused by the collapse of the sea floor.

It has been reported that mainly two destructive waves struck most coastal towns of Sri Lanka on the last 26th of December. There has been a spectacular recession of the sea exposing the sea floor to a distance of about 1 km from the shore in many places during the time interval between the two waves. It may be interpreted that the Jeffery phase with reduced amplitude may be responsible for the initial wave, which was not very strong. The Jeffery phase will be followed by the first trough of the oscillatory phase, which is responsible for the recession of the sea. As explained earlier a trough of water waves are formed as a result of horizontal movements of the water towards the crests and this further explains complete depletion of water exposing the sea floor. Then the first crest of the oscillatory phase will come with enhanced amplitude and most of the devastation will be caused by this stronger second wave. It is possible for several other waves also to come, but their severity would depend on several other factors.

Alteration of Direction and Penetrating into Shadow Areas

When a wave undergoes change in velocity it normally suffers a change in its direction of propagation. This phenomenon is known as refraction. Tsunami waves also can undergo refraction as a result of change in velocity due to the change in depth of the water column in which they are travelling. Sharp variation of the topography of the sea floor due to the presence of oceanic ridges and massive seamounts are capable of guiding the direction of tsunamis in this manner. Capability of a wave front to bend at an obstacle and reach areas covered by the obstacle is known as diffraction. Any wave type has this capability and the extent to which it can penetrate into the covered area is limited to a distance of the order one wavelength. This phenomenon may responsible for the tsunami waves that originated near Sumatra, which faces the eastern coast of Sri Lanka to reach its western coast. As the wavelength of the tsunami is of the order of 200 km it can easily affect the western coast even upto Negombo due to the diffraction phenomena.
In the recent tsunami we noticed that Maldives, which is an oceanic atoll, is comparatively less affected in spite of its seemingly vulnerable position in the Indian Ocean. The safeguards available to atoll dwellers are twofold. First of all the atoll isles rise steeply from the sea floor like pinnacles and there is no desirable topography of the sea floor for the wave to enhance its amplitude. Further, most of the isles have dimensions less than the wavelength of tsunami waves and therefore the waves will pass the isles almost “unnoticed”.

Tsunami Warning System and Public Awareness Programme

After the tragic events of December 26th many professionals and several others have urged the government to consider the possibility of having an early tsunami warning system in Sri Lanka. There is such a system that covers most countries in the Pacific Basin, Hawaii islands and other US regions bordering the Pacific Ocean. Basically a tsunami warning system is an international network of seismometers (or seismic observatories) and “tide stations” installed in relevant countries and relevant sea areas. These instruments are connected to a central station via satellite. The central station may also have access to other international seismic networks such as the one owned by the United States Geological Survey. Seismometer network will indicate occurrence of earthquakes in the region covered by the network and the geophysicists in the central station will compute the location and the magnitude of the earthquake. If the earthquake has taken place in a vulnerable sea area and if its magnitude is reasonably high (more than 7 on the Richter scale) they can examine readings of the tide gauges in the vicinity of the focus of the earthquake to see any signs of the formation of a tsunami. Warning bulletins will then be issued to the member countries if the necessity arises.

A tsunami warning system cannot be established by a single country. Several countries in a region, which are likely to be threatened by this natural disaster, will have to work together in establishing such a system. Therefore there are practical difficulties in establishing an early tsunami warning system immediately. Until such time we establish a suitable early warning system we may think of having our own improvised warning system. This system may consist of a small group of scientifically oriented dedicated people who work around the clock in a central station. They should examine seismic records at Pallekele and other stations or which we have access and compute the location and magnitude of any earthquake recorded. These computations do not require much advanced knowledge of seismology. Any person with reasonably good background of physics and mathematics and some exposure to computing can be easily trained for this purpose. They can also be on alert for news reports coming from neighbouring countries and warning bulletins issued by already established tsunami early warning centres and any other relevant information appearing on the internet. If a centre of this nature is available any outside agency that would like to warn us regarding an impending disaster can direct such warnings to this centre.

Sri Lanka has been generally considered a safe country with regard to natural disasters. Droughts and floods are the most frequently heard natural disasters. Sometimes heavy rains are reported to have triggered off landslides especially in the upcountry. Earthquakes of magnitude of the order of 5 or less on the Richter scale have been felt occasionally only arousing academic interest. Articles in the press by the experts often appear to reassure the safety of Sri Lanka soon after such events. Popular belief among many of us was that there is no need to worry about earthquakes and tsunamis, as they are not “destined” to occur in Sri Lanka. This false sense security that has been developed over the years has contributed much towards our ignorance with regard to extreme natural disasters. Our failure to realise the possibility of having a tsunami after a submarine earthquake exceeding magnitude eight on the Richter scale off the coast of Sumatra explains the extent of our ignorance regarding these matters. Had the general public being knowledgeable about recession of the sea immediately prior to the arrival of the major tsunami wave they would have gone to safe places resisting the natural tendency to take advantage of once in a life time opportunity of exploring the exposed sea floor. All these are sad and grim reminders of our ignorance about natural disasters. The importance of having a comprehensive long-term programme to educate the general public with regard to such disasters has become an urgent need of the country. Earthquakes and tsunamis should occupy a centre place of this educational programme. Different aspects of natural disasters including scientific as well as sociological aspects should come into our education system at different levels starting from he junior school to postgraduate level in the universities. Scientists will have the arduous task of understanding how these disasters originate and how they affect the different parts of the county and to draw up risk mitigation strategies. Finally through the media and education system of the country this knowledge should steadily permeate down to the general public. Intellectuals, educators and journalists of Sri Lanka have an enormous responsibility giving leadership to the initiation an effective awareness programme.

Part 1>
Origin of Earthquakes

Understanding Earthquakes and Tsunamis – part 1

Prof Dhammika A. Tantrigoda
Department of Physics, University of Sri Jayewardenepura
Nugegoda, Sri Lanka

Dreadful memories of the tsunami that ravaged several coastal cities of Sri Lanka claiming many innocent lives on the early hours of 26 December 2004 is still haunting the minds of many of us. This powerful tsunami, which devastated several South Asian countries, originated off the west coast of Sumatra. According to local and international news agencies, the tsunami has claimed well over 150 000 lives causing unprecedented damage to property. It has been generated as result of a massive Earthquake of magnitude 9 on the Richter scale. According to the United States Geological Survey, this is the fourth largest earthquake in recorded history, the largest being the great Chilean Earthquake that took place in 1960, with a magnitude of 9.5 on the Richter scale.

Tsunami is a train of sea waves triggered off due to a sudden collapse of the ocean floor. This normally happens as a result of earthquakes taking place at shallow depths below the sea floor. Tsunamis can also be caused by volcanic eruptions and falling of large boulders into the water. Violent eruption of Krakatoa volcano in 1883 caused sudden collapse of the sea floor leading to a massive tsunami, which claimed a large number of human lives. Tsunamis are sometimes referred to as tidal waves. This is a misnomer, as tsunamis have nothing to do with tides that are caused by the gravitational attraction of the sun, moon and other planetary bodies. The word tsu-nami has a Japanese origin and it means harbour wave (“tsu” means harbour while “nami” means wave). Tsunamis have enhanced effects in harbours and other U or V shaped water inlets and this could have been contributed towards the Japanese origin of the word.

Origin of Earthquakes

Figure 1

Let us now see how earthquakes that trigger tsunamis are originated. The thin outermost part of the earth (first 50 to 100 km) is known as the lithosphere and it consists of several large detached tile like segments and several other such smaller segments. These segments are known as lithospheric plates or simply plates. Plates “float” on a region called asthenosphere, which consists of rocks that have transformed into an extremely “thick” or viscous material, which can flow with very slow speeds. All the plates are moving relative to each other at very slow speeds in a complicated manner. Earthquakes can be observed in most plate margins, especially at the vicinity of plate margins known as transform faults and subduction zones. At a transform fault two plates move passing each other horizontally. One such plate margin is in California in western USA. This is known as San Andreas Fault and many powerful earthquakes have been generated at this fault. At a subduction zone a heavy oceanic plate goes under a relatively light continental plate (figure 1). Descending oceanic plate tries to drag along some of the adjacent continental plate resulting strains in both plates. So the subduction does not proceed smoothly and continuously; it proceeds with jerks and each jerk is responsible for an earthquake. The oceanic plate on which most of the Indian Ocean is lying on is plunging down (subduct) under Indonesia and the recently observed magnitude 9 earthquake took place at this plate boundary.

Trigger Mechanism

No one exactly knows the mechanism that triggers earthquakes as they happen deep down in the earth. However, we can build models to explain how earthquakes occur in just as we build models to explain atomic and nuclear phenomena. The elastic rebound model is one such model that has been built to explain the origin of earthquakes that takes place at a transform fault. It is useful to study this model as it gives a very good insight into how earthquakes originate. As discussed earlier, at a transform fault two plates move passing each other almost horizontally. Due to frictional and other forces each plate is trying to stop the motion of the other that result in deforming both plates. This is somewhat similar to two gigantic rubbers glued to each other trying to move in opposite directions parallel to the two faces that have been glued. As a result of relative motion of the parts of the rubbers that are away from the glued boundary they get deformed and are in a state of strain. The figure 2.b shows the way in which two plates can undergo deformation in this manner. There is a limit to which “glued” rocks can withstand deformation and once this limit is passed, rocks in that region snap releasing huge amounts of energy. This is how the elastic rebound model explains the origin of an earthquake. Normally the whole boundary of “glued” plates does not get dislocated in one instance. Only the rocks in a certain region of the boundary get dislocated and this has been illustrated in figure 2c. If the extent of the dislocation is large the release of elastic energy is also large and the earthquake is classified as one having higher magnitude. Once the main shock occurs, other parts of the glued regions can also snap and release energy and these events are known as after shocks. This explains how several small earthquakes that were reported to have taken place at the same plate boundary occurred after the massive earthquake of 26th December. After shocks are normally not powerful as the main shock. Sometimes a small release of energy can take place before the main shock known as foreshocks. Dislocation of rock units over an extensive region on the plate will take place in an earthquake. However, compared to the size of the whole plate boundary this region can be well approximated to single point. This point is known as the focus of the earthquake. The point directly above the focus on the surface of the earth is known as the epicentre of the earthquake.

figure 2

When an earthquake takes place basically two types of waves collectively known as “body waves” transmit the energy outwards. Once these waves reach the surface their interference with each other and other phenomena will lead to the formation of another type of waves known as “surface waves”. Unlike body waves surface waves have higher amplitudes and almost all the physical damage due to an earthquake is due to the effects of surface waves. How the body waves and surface waves are generated and how they travel and also how the whole earth vibrates like a giant bell after an earthquake is a fascinating problem in physics and in applied mathematics. Some of the concepts in physics and mathematical tools developed to solve this problem have been successfully used in formulating some of the concepts in advanced branches of contemporary physics such as quantum mechanics and nuclear physics.

Part 2 >
Richter Scale Magnitude of Earthquakes