Tilak Priyadarshana

• PhD
• Professor at University of Ruhuna

Atmospheric water vapor stable isotopes are crucial for understanding hydrological cycle processes under climate change. This study presents the results from a year-long in situ monitoring of atmospheric water vapor stable isotopes (δ18O, δD) at Matara, Sri Lanka, from March 2020 to February 2021 to assess how oceanic sources and moisture transport...

Flooding is a major risk in tropical regions, with Sri Lanka especially vulnerable due to its vast river network. The present study examined the Nilwala River catchment in the Southern Province, a region experiencing recurrent flooding intensified by climate change and rainfall variability. To enhance flood forecasting, we developed a model using H...

In parallel with climate changes, understanding tropical rainfall dynamics becomes crucial for effective decision-making in agriculture, water management, and disaster preparedness. Sri Lanka, situated in the tropical Indian Ocean (IO), is particularly vulnerable to climatic shifts, especially concerning rainfall patterns. Despite this vulnerabilit...

Air–sea exchanges play a crucial role in intense weather events over Sri Lanka, particularly by providing the heat and moisture that fuel heavy rainfall. We present a year-round dataset of meteorological observations from the southern shoreline of Sri Lanka in the equatorial Indian Ocean for 2017, aiming to investigate its seasonal characteristics...

Atmospheric water vapor stable isotopes are crucial for understanding hydrological cycle processes under climate change. This study presents a year-long in-situ monitoring of atmospheric water vapor stable isotopes (δ18O, δD) at Matara, Sri Lanka, from March 2020 to February 2021 to assess how oceanic sources and moisture transport influence coasta...

The characteristics of local surface wind are closely related to the assessment of wind power resources and the oscillation period of offshore wind turbines. In this research, we analyzed near-surface wind observation data from the southern coast of Sri Lanka, comparing the surface wind variation characteristics across different seasons. Through sp...

An opportunistic study was carried out from a 113’ motor-sailing vessel along the southeast coast of Sri Lanka from April 11 to 19, 2013. Passive acoustic monitoring allowed pods of sperm whales (Physeter macrocephalus) to be detected and tracked before being sighted. Key observations included sightings of whales along the 1000 m drop-off, repeated...

During the southwest monsoon, a cold dome referred to as the Sri Lanka Dome (SLD) appears east of Sri Lanka in response to the cyclonic curl in the local wind field. In general, SLD forms around May/June and decays during September. However, satellite altimetry data revealed an anomalous propagation pattern of the SLD with a lifetime of more than s...

Benzotriazoles, benzothiazoles, and p-phenylenediamines discharged from wastewater treatment plants (WWTPs) are of concern because they pose risks to aquatic organisms. South/Southeast Asian countries are heavily populated and face challenges in providing clean water. Here, the chemical fates in five WWTPs in Malaysia and Sri Lanka were investigate...

Land-use changes due to urbanization influence the surface runoff. Therefore, surface runoff assessment has become crucial in urban areas, since the increment of surface runoff leads to the occurrence of floods, soil erosion, and pollutants transportation. Rapid urbanization is mostly being observed in cities of developing countries. Matara city is...

Blue Economy is a way of deriving the economic growth of a nation through its contribution from the ocean and coastal-based activities while assuring environmental sustainability and livelihood development. Sri Lanka is an island nation of the Indian Ocean with an Exclusive Economic Zone (EEZ) of approximately eight times its terrestrial extent tog...

Time series measurements (2010–2017) from the Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction (RAMA) moorings at 15°N, 90°E and 12°N, 90°E are used to investigate the effect of the seasonal barrier layer (BL) on the mixed-layer heat budget in the Bay of Bengal (BoB). The mixed-layer temperature tendency (∂T/∂t) is...

Land use changes in a particular area, due to urbanisation and deforestation is, influenced by the surface runoff and the dispersion of non-point source pollutants. Surface runoff assessment has become important, as increment of surface runoff leads to the occurrence of floods, soil erosion and pollutant transport. In this study, the relationship b...

The interannual variability of summertime eddy-induced heat transport (EHT) in the western South China Sea (WSCS) is investigated based on the downgradient eddy diffusivity method and explored its formation mechanism. Estimations of long-term mean EHT and its monthly evolution reveal that the largest EHT in the SCS occurs in the WSCS region during...

As an important part of the Indo-pacific warm pool, the Indian Ocean has great significance for research on the Asian monsoon system and global climate change. From the 1960s onwards, several international and regional programs have led to important new insights into the Indian Ocean. The eastern Tropical Indian Ocean Observation Network (TIOON) wa...

The 2030 Agenda for Sustainable Development, adopted by all UN member states, provides a policy framework for achieving sustainable development goals. The 13th SDG: Climate Action is fully dedicated to ‘taking urgent action to combat climate change and its impacts’. Increasing storage is a key adaptation strategy in the water sector, and restoratio...

Utilisation of water harvesting systems of ancient origin for present-day requirements can be seen in many regions of the world. The adoption of ancient tank cascades as the smallest hydrological unit of river basin development in Sri Lanka is such a practice. However, these systems are associated with unsuccessful experiences in agricultural perfo...

Following Decision 1/CP.21 of the Conference of the Parties, Sri Lanka has identified Nationally Determined Contributions for adaptation to climate change. Restoration and rehabilitation of all abandoned tanks is one such contribution in the irrigation sector. The country has around 13,600 working village tanks of ancient origin. These restored tan...

During the southwest monsoon, a cold dome referred to as the Sri Lanka Dome (SLD) appears east of Sri Lanka in response to the cyclonic curl in the local wind field. In general, SLD forms around May/June and decays during September. However, satellite altimetry data revealed an anomalous propagation pattern of the SLD with a lifetime of more than s...

Diatoms are widely used in monitoring environmental contamination and serve as bio-indicator for water quality and pollution status and they are more sensitive to the small variations in the environment as compared to other macrophytes and benthic algae. Objectives of this study were (a) to identify diatom species found in canals of Colombo with va...

This study investigates basin and regional‐scale eddy (turbulent)‐induced heat and salt transport associated with mesoscale eddies of the Bay of Bengal (BOB). A high level of eddy‐induced transport is found in four subregions: the western boundary of the northern BOB (NB), the western BOB (WB), the southwestern BOB near Sri Lanka (SWB), and the sou...

Headwater regions of the streams consist an array of unique biological communities, and these ecosystems are considered the most sensitive element of river ecosystems. The significant role played by these ecosystems are well documented but the information relevant to Sri Lankan water bodies is very limited. Thus, the present study was designed to s...

Headwater regions of the streams consist of an array of unique biological communities, and these ecosystems are considered the most sensitive element of river ecosystems. The significant role played by these ecosystems are well documented but the information relevant to Sri Lankan water bodies is very limited. Thus, the present study was designed t...

Most of the monitoring data on the occurrence of antibiotics in sewage treatment plants (STPs) have been reported from Europe, North America and some countries in Northeast Asia, while very limited data can be found in Southeast Asian countries. As a pioneering research in Sri Lanka, we collected 24 h composite wastewater samples at the influent an...

Belt and Road Initiative (BRI) is a Chinese national strategy which calls for cooperative economic, political and cultural exchange at the global level along the ancient Silk Road. The overwhelming natural hazards located along the belt and road bring great challenges to the success of BRI. In this framework, a 5-year international program was laun...

Ｓａｌｉｎｉｔｙ ｄａｔａ ｆｒｏｍ ｔｈｅ Ｏｃｅａｎ Ｒｅａｎａｌｙｓｉｓ Ｓｙｓｔｅｍ （ＯＲＡＳ４） ｔｈａｔ ｉｍｐｌｅｍｅｎｔｅｄ ｂｙ ｔｈｅ Ｅｕｒｏｐｅａｎ Ｃｅｎｔｒｅ ｆｏｒ Ｍｅｄｉｕｍ⁃Ｒａｎｇｅ Ｗｅａｔｈｅｒ Ｆｏｒｅｃａｓｔｓ （ＥＣＭＷＦ），ｈａｖｅ ｂｅｅｎ ｕｓｅｄ ｔｏ ｓｔｕｄｙ ｔｈｅ ｉｎｔｅｒａｎｎｕａｌ ｖａｒｉａｂｉｌｉｔｙ ｏｆ ｍｉｘｅｄ ｌａｙｅｒ ｓａ⁃ ｌｉｎｉｔｙ ｉｎ ｔｈｅ Ａｒａｂｉａｎ Ｓｅａ Ｍｉｎｉ Ｗａｒｍ Ｐｏｏｌ （ＡＳＭＷＰ） ｄｕｒｉｎｇ ｔｈｅ ｐｅｒｉｏｄ ｏｆ １９９９－２００９．Ａｐａｒｔ ｆｒｏｍ ｔｈｅ ｂｒｏａｄ ａｇｒｅｅ⁃ ｍｅｎｔ ｗｉｔｈ ｔｈｅ ｐｒｅｖｉｏｕｓ ｓｔｕｄｉｅｓ ｏｎ...

Based on reanalysis data, we find that the Indian Ocean Dipole (IOD) plays an important role in the variability of wave climate in the equatorial Northern Indian Ocean (NIO). Significant wave height (SWH) in the equatorial NIO, especially over the waters southeast to Sri Lanka, exhibits strong interannual variations. SWH anomalies in the waters sou...

As per the analysis, the dams of the two major tanks (Hambegamuwa and Mahagama tanks) had been placed on hard Granite or biotite bedrocks. The majority of the tanks (66 %) were located on the reddish-brown soil and in the Intermediate climatic zone (36 tanks per 25km 2), while the lowest (3 tanks per 25 km 2) was in Semi-Arid Zone. About 50 % of th...

Time series measurements from the Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction (RAMA) mooring at 15°N, 90°E in the vicinity of the cyclone passage Maarutha and Mora, are used to investigate the upper ocean variability, variations of the cyclone heat potential (CHP) and the importance of cyclone induced vertical...

A three-dimensional Princeton Ocean Model (POM) along with the Observed hourly sea level data are used this study to investigate the characteristics of the Tide-Surge Interaction (TSI) along the north coast of Sri Lanka in North Indian Ocean. In this study, the cyclone ‘Nisha’ 2008 case was selected and three numerical experiments were performed. T...

We present a continuous in situ hydro-meteorology observational dataset from a set of instruments first deployed in December 2012 in the south of Sri Lanka, facing toward the north Indian Ocean. In these waters, simultaneous records of wind and wave data are sparse due to difficulties in deploying measurement instruments, although the area hosts on...

Time series measurements from the Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction (RAMA) moorings at 15° N, 90° E; 12° N, 90° E; 8° N, 90° E; 4° N, 90° E; 1.5° N, 90° E; 0° N, 90° E are used to investigate the seasonal mixed-layer heat balance and the importance of barrier layer thickness (BLT) and vertical mixing...

In the view of energy, the interannual variability of eddy-mean flow interaction around the Vietnam Offshore Current (VOC) in summer (June-September) from 1992 to 2011 was investigated by use of the REDOS (Reanalysis Dataset of the South China Sea) and the CCMP (Cross-Calibrated, Multi-Platform) ocean surface wind. The relative importance of wind s...

We present the first continuous in situ hydro-meteorology observations from the south of Sri Lanka from a set of instruments deployed firstly in December 2012. The simultaneously record wind and wave data in this region are sparse due to difficulties in deployment. Here the survey, deployment and measurements of wind and wave are described with the...

This study was conducted to determine the present status of the Mud Crab (Scylla serrata Forskal) population in Koggala Lagoon, including details on size at maturity, sex ratio and carapace width-body weight relationship. This Crab is the most common edible Crab species found in the lagoon, comprising 93.10% of total catch from crab pots and 89.86%...

Using hydrographic data with geostrophic calculation and normal mode analysis along the 120°E transect in September from 2005 to 2009, 2011, and 2013, we revealed the vertical characteristics and interannual variation of the velocity fields in the northeastern South China Sea (SCS). Results show that, the direction of velocity fields in 2005, 2006,...

Surveys were conducted off the southern coast of Sri Lanka in 2014 and 2015 to investigate the distribution patterns of blue whales (Balaenoptera musculus spp.) in relation to current shipping lanes, and further offshore. There have been several reported ship strikes of blue whales in this area and the IWC Scientific Committee has recognised the po...

The sown area is continuously being increased in Hambanthota district; the rice production has not fulfilled its expected optimum yield. As the agriculture is mainly based on the rainfalls received to this region, the sentiment of the farmers on this matter is the shift of the crop season due to the climatic consequences. However, no proper scienti...

A new bulk parameter, Lagoon Richardson Number (RiL), was developed based on the Estuarine Richardson Number (RiE) to characterize the mixing/stratification process of permanently open choked coastal lagoons (POCCLs) in Sri Lanka. In addition to tidal induced mixing, wind induced mixing is also incorporated in RiL. Furthermore, the estuarine bulk m...

The sown area is continuously being increased in Hambanthota district; the rice production has not fulfilled its expected optimum yield. As the agriculture is mainly based on the rainfalls received to this region, the sentiment of the farmers on this matter is the shift of the crop season due to the climatic consequences. However, no proper scienti...

Especially, in dry and Semi-arid areas of the world are suffering from lack of water due to ignorance of finding new opportunities to overcome water scarcity. Similarly, Walawe river basin (WRB) which lies in the dry and semi-arid zone of Sri Lanka has a higher demand for water in Agricultural, Industrial, and Domestic uses. More than 600 small sca...

The present study indicates that for the first time in Sri Lanka Indian major carps, viz, Catla (Catla catla), Rohu (Labeo rohita) and Mrigal (Cirrhinus mrigala) breed and spawn naturally in Udawalawe reservoir, a man-made perennial reservoir in Sri Lanka with the advent of the North-east monsoon rainy season. Shallow inundated banks of the Walawe...

Garanduwa is a small lagoon located in the Matara District extending for nearly 0.32 sq. km. The lagoon lies in the Lowland Wet Zone of the country and floristically it belongs to the ‘Southern Wet Lowlands’. The natural mouth canal (Mirissa Udupila Ela) is about 2 km in length and connects to the sea at Mirissa, however this canal is not functiona...

Madampe lagoon has been subjected to the influence of anthropogenic activities for many centuries. Its watershed drains water rich in nutrients and organic matter from a relatively heavily populated catchment area and as a result the lagoon has faced the threat of the degradation of water quality. Unabated pollution in the lagoon has drastically af...

Nanthikadal is relatively a large lagoon located in the Mullaitivu District extending for nearly 3,120 hectares. This particular lagoon is connected to the sea by a narrow long mouth about 2 km in length and meets the sea at Wadduwakkal. The lagoon lies in the Warm lowland of the Dry Zone - categorically known as Northwestern Lowland Dry Zone of th...

Rekawa lagoon is a choked and shallow coastal water body located in the southern coast of Sri Lanka (6 03N – 80 50E) and connected to the sea with a 3 km long narrow canal. The major freshwater input, Kirama-oya river is connected to the narrow canal nearly 300 m away from the lagoon mouth. A causeway has been constructed in the year 1984, nearly 7...

The changes of natural sensitivity in terms of lagoon morphometry, particularly the inlet morphometry and flushing properties of the Koggala lagoon, Sri Lanka, are presented in this paper. The morphometric assessment is based on analysis and consideration of morphometric characteristics for three scenarios of the lagoon, namely: (1) before the cons...

Physical processes of the lagoon are influenced by structural interventions. Understanding the complex reality of physical processes sometimes difficult with field observations thus a model provides a simplified abstract view. Two dimensional hydrodynamic model is used to describe, restoration efforts to Koggala lagoon, a combined freshwater and es...

Groyne system modification is described related to restoration efforts to Koggala lagoon, Sri Lanka.The large-scale unplanned sand removal at the lagoon mouth shifted the formation of sand bar towards the lagoon and made adverse effects on its ecosystem. After the removal of the natural sand bar, groyne system was constructed to avoid sand depositi...

Koggala lake is a combined freshwater and estuarine complex of rich ecosystem on the southern coast of Sri Lanka. After the natural sand barrier at the outlet was removed, groyne was built. However the groyne resulted in the lake outlet being permanently open which in turn led to many environmental problems. Cost effective rubble mound structures a...

Malala-Embilikala Lagoon system comprises two water bodies: Malala and Embilikala connecting each other through a natural narrow canal (in Sinhala it is called Ooday) and is located in the Bundala Ramsar Wetland. In 1991, Bundala was declared as a Ramsar site, which contains 6,210 ha and is the largest Ramsar wetland out of the three Ramsar wetland...

Rathgama Lagoon is a shallow coastal body of water separated from the ocean by a sand barrier which lies parallel to the shoreline. Inlet, either natural or man-made, cut through sand barrier permit tidal currents to transport water into and out of the Rathgama Lagoon. The beach close to the lagoon mouth has been traditionally used to a boat landi...

In littoral zones of aquatic systems, submerged macrophytes have marked structural variation that can modify the foraging activity of planktivores. Swimming and feeding behavior of Pseudorasbora parva and Rasbora daniconius (Cyprinidae) on their prey Daphnia pulex and Artemia salina, respectively, was studied in a series of laboratory experiments w...

As a direct consequence of large-scale sand removal in early 1990s in the Koggala lagoon mouth, the natural process of sand bar formation was severely disturbed and formation of the new sand bar shifted towards the Kathaluwa Bridge, which exposed the bridge to wave attack. Breaching the sand bar became increasingly difficult and erosion close to th...

The feeding and swimming behaviors of Pseudorasboraparva and Rasboradaniconius (Cyprinidae) with two different prey types (Daphniapulex and Artemiasalina) at different densities (0.5, 1, 2, 5, 10, or 25perl) were studied after 36h of food deprivation. Full satiation was defined as the cumulative number of attacks performed until fish attain a const...

As macrophytes have considerable structrual variation for prey communities by hindering predator foraging and affect the predator behavior, the swimming and feeding behavior of planktivore (Pseudorasbora parva) with their prey (Daphnia pulex) were studied in laboratory experiments with varying densities (350, 700, 1400, 2100 and 2800 stems·m⁻²) of...

In the littoral zones of lakes, aquatic macrophytes produce considerable structural variation that can provide protection to prey communities by hindering predator foraging activity. The swimming and feeding behaviour of a planktivore, Pseudorasbora parva(Cyprinidae) on its prey (Daphnia pulex) was studied in a series of laboratory experiments with...

Hunger affects the feeding and swimming behaviour in fish. After 36 h of food deprivation, the feeding and swimming behaviour of Pseudorasbora parva (Cyprinidae) was studied under different prey densities (0.5, 1, 2, 5, 10 and 25 of Daphnia pulex per liter). The initial feeding rates showed marked variations in relation to prey availability. Under...

Aquatic macrophytes produce considerable structural variation within the littoral zone and as a result the vegetation provides refuge to prey communities by hindering predator foraging activities. The behavior of planktivorous fish Pseudorasbora parva (Cyprinidae) and their zooplankton prey Daphnia pulex were quantified in a series of laboratory ex...

Sri Lanka is located in the Indian Ocean between the latitudes 5° 51′ and 9° 51′N and longitudes 79°41′ and 81°51′E. Themain island which is roughly pear shaped extends maximally 445 km North-South and 225 km East-West with a land area of 65,610 sq km. The island has a coastal plain which extends on all sides and a south-central mountainous region...