Asian Institute of Technology
University of Moratuwa
Poojitha D. Yapa, a Professor of Civil and Environmental Engineering at Clarkson University, Potsdam, NY, USA has B.Sc (Honors) in Civil Engineering and M.Sc in Hydraulic engineering. He received his Ph.D. in Civil and Environmental Engineering from Clarkson University. For over 30 years, his research has focused on a variety of “environmental hydraulics problems”: oil spill modeling (trajectory modeling as well as physico-chemical processes), oil behavior in ice covered waters, modeling deepwater oil, gas, and hydrates. These studies led Prof. Yapa and his students to develop computer models CDOG, MEGADEEP, and ADMS. The group also developed MOTHV, a model that simulates deepwater hydrothermal vents. All this work has been published in leading journals.
Prof. Yapa received the prestigious Erskine fellowship from New Zealand and Gledden Fellowship from Australia for long term visits to their Universities. He has also been invited for long term visits to Universities in Japan, Singapore, and Portugal. He has given over 60 invited seminars in 10 countries. He has numerous publications in leading Hydraulic Engineering and research journals and has been the associate editor of hydraulic journals of ASCE as well as the IAHR. Prof. Yapa chaired the Task Committee on Modeling of Oil Spills, ASCE. During the Horizon oil spill in the Gulf of Mexico Prof. Yapa was an adviser to NOAA (US government) on Deepwater plumes as well as a member of the Flow Rate Task Group (FRTG). IAHR appointed Prof. Yapa to be the chair of the work group on oil spill modeling (2010- to date). He received United States Geological Services (USGS) director’s award for exemplary services to the nation for the work he did during 2010 Deepwater Horizon oil spill response.
Modeling deep water oil and gas jets/plumes, Modeling surface oil spills, Oil and Gas droplet sizes in water, Modeling physico-chemical processes that oil undergo in ocean conditions, Modeling Hydrothermal Vents in deepwater, Modeling CO2 and CH4 hydrates in deepwater, Oil transport and spread in ice covered waters.
United Sates Geological Survey (USGS) Director’s award for the exemplary service to the nation - Deepwater Horizon (2010)
Associate Editor of Journal of Hydro-Environment of Research - International Association of Hydraulics Research (IAHR)/ Elsevier : 2006 - present
Erskine Fellowship, Department of Civil Engineering, University of Canterbury, Christchurch, New Zealand, 2007
Associate Editor of ASCE Journal of Hydraulic Engineering : 2001 - 2006
Gledden Senior Visiting Fellowship, Centre for Water Research, The University of Western Australia, Perth, Australia, (1999-2000)
Invited Research Fellow, Department of Civil Engineering, Science University of Tokyo, Japan, (1992 - 1993)
Invited Researcher, Environmental Assessment Dept., National Institute for Resources and Environment, Tsukuba, Japan, (1992)
Recipient of the United Kingdom Government Scholarship (1977 - 1979)
Models Developed (selected)
ADMS ~pronounced ˈadams’ -(Advanced Deepwater Modeling Suite)
ADMS consists of a suite of models/modules to simulate the fate and transport of oil, gas, and hydrates when released from shallow to ultra-deep water. The simulations allow gas hydrate formation, dissociation as well as hydrate dissolution. The suite includes CDOG, MEGADEEP, and OILDROPLETS. For details see the research website.
CDOG ~pronounced 'sea dog’ (Comprehensive Deepwater Oil and Gas) Model
CDOG developed at Clarkson University by Prof. Yapa and his students was the model used by NOAA to simulate the behavior of oil during the 2010 Horizon deepwater spill in the gulf of Mexico. CDOG (a 3D Model) simulates the behavior of oil and gas accidentally released from deep water. In deepwater, the ultra-high pressure and cold temperature causes phase changes in gasses. CDOG simulates all these changes as well as other complex processes.
MEGADEEP (Methane Gas in Deepwater) Model
MEGADEEP is a 3D model specifically designed to simulate the transport and fate of gasses (methane and natural gas) and hydrates accidentally released in deepwater. It takes the following processes into account: Mass conservation, Hydrodynamics and thermodynamics of the plume, Advection/Diffusion of the plume, possible gas separation from the plume, Gas dissolution, Hydrate formation and dissociation, and Hydrate dissolution.
OILDROPLETS Model to compute droplet sizes and distribution ( in deepwater or surface spills)
OILDROPLETS Model can compute the sizes and distribution of oil droplets when oil is released in deepwater as a jet or plume or in near surface oil spills when oil slick is broken up by waves and entrained into the water column. OILDROPLETS is a new phenomenological based model, unlike other older work available as empirical formulas. OILDROPLETS dynamically simulates oil droplet formation by considering droplet breakup and coalescence.
MOHTV ~pronounced 'mō-tiv’ (Model for Hydrothermal Vents)
MOHTV is a 3D model developed to simulate the behavior of underwater hydrothermal vent plumes. It models physical, chemical, and biological processes that take place in hydrothermal vents due to the discharge of super-hot water rich in minerals to determine the quantities of minerals produced during their spread in the ocean water column, and the extent of their spread on the ocean floor.
OCEAN_CO2 Modeling the Ecological Impact of CO2 Releases in ocean waters
This model simulates the ecological impact due to CO2 gas releases from moderate ocean depths. It can handle releases from a single point, or releases spread over an area. OCEAN_CO2 calculates dissolved CO2 concentration, pH, and TCO2 in water. The model results compared very well with the data from natural CO2 releases in Kagoshima Bay, Japan.
SPEED (Sediment Plume and Environmental Effect from Deep-sea Mining)
SPEED model is a 3D model which can simulate sediment plumes and their impact when released upwards in Deep Sea.
COMBOS3D (Three-Dimensional Comprehensive Oil Spill Model for Surface and Underwater spills)
This 3D model can simulate oil spills on water surface or spills that originate as jets or plumes underwater. COMBOS3D can simulate fate and transport of oil after a spill. It considers the following processes: Advection, Horizontal diffusion, Spreading, Vertical mixing, Evaporation, and Dissolution. The model has been extensively tested against available data.
DEPOSE (A Model for simulating Dissolution, Evaporation, Photo-Oxidation, Sedimentation, and Emulsification after an oil spill)
This model simulates the physical-chemical behavior of oil after a spill. In addition to advection/ diffusion and vertical mixing of oil, DEPOSE simulates oil Emulsification, Oil- sediment interaction, Evaporation, Dissolution, and Photo-oxidation.
SHIP LEAK (A Model to Simulate Oil Leaks form Sunken Ships)
This is a simplified version of COMBOS3D specifically designed to simulate oil leaks from sunken ships.
WINROSS - An Integrated Oil and Chemical Spill Model for Rivers
WinROSS is the windows based (interactive and GUI Menu based) version of our River Oil Spill Simulation Model (ROSS).
Premathilake, L. T., Yapa, P. D., Nissanka I. D., and Kumarage, P. (2016) “Impact on Water Surface due to Deepwater Gas Blowouts,” (accepted for publication) Marine Pollution Bulletin, Elsevier.
Premathilake, L. T., Yapa, P. D., Nissanka I. D., and Kumarage, P. (2016) “Modeling the flow regime near the source in underwater gas releases,” Journal of Marine Science and Applications (accepted for publication)
Nissanka, I. D., and Yapa, P. D., (2016) “Calculation of oil droplet size distribution in an underwater oil well blowout,” Journal of Hydraulic Research, IAHR /Taylor and Francis, Vol 54, No. 3, pp 307-320
Wimalaratne, M. R., Yapa P. D., Nakata, K., and Premathilake, L. T. (2015). “Transport of dissolved gas and its ecological impact after a gas release from deepwater,” Marine Pollution Bulletin, Elsevier, 100 (1), 279-288.
Dissanayake,A. L., Yapa, P. D., and Nakata, K., (2014). "Simulation of Hydrothermal Vents in the Izena Cauldron, Mid Okinawa trough, Japan and other Pacific Locations," Journal of Hydro-Environment Research, IAHR/Elsevier, Vol 8, pp. 343-357
Dissanayake, A. L., Yapa, P. D., and Nakata, K., (2014). "Modeling of Hydrothermal Vent Plumes to Assess the Mineral Particle Distribution," Journal of Hydraulic Research, IAHR, Vol. 52, No. 1 (2014), pp. 49-66
Yapa, P.D. (2012). “Modeling Oil Spills to Mitigate Coastal Pollution,” in H. J. S. Fernando (ed) , Handbook of Environmental Fluid Dynamics, Taylor & Francis Books Inc., Dec., 243-255.
Yapa, P. D., Wimalaratne, M. R., Dissanayake, A. L., and De Graff Jr., J. A. (2012) “How does oil and gas behave when spilled underwater,” Journal of Hydro-Environment Research, IAHR/Elsevier, 6, 275-285
Yapa, P. D., and Dissanayake, A. L (2012). “Discussion on A Model to Simulate the Transport and Fate of Gas and Hydrates Released in Deepwater, Journal of Hydraulic Research, IAHR. Vol. 50, No. 6 (2012), pp. 646–649
Dissanayake, A. L., DeGraff Jr., J. A., Yapa, P. D., Nakata, K., Ishihara, Y., and Yabe, I. (2012). Modeling the Impact of CO2 Releases in Kagoshima Bay, Japan,” Journal of Hydro-Environment Research, IAHR/Elsevier, 6 (2012) 195-208.
Bandara, U. C., Yapa, P. D., Xie H., (2011). “Fate and Transport of Oil in Sediment Laden Marine Waters,”. Journal of Hydro-Environment Research, IAHR/Elsevier, 5, 145-156.
Bandara, U. C., and Yapa, P. D., (2011). Bubble Sizes, Break-up and Coalescence in Deepwater Gas/Oil Plumes, Journal of Hydraulic Engineering, ASCE, 137,729-738.
Yapa, P. D, Dasanayaka, L. K., Bandara, U. C., and Nakata, K. (2010). “A Model (MEGADEEP) to Simulate the Transport and Fate of Gas and Hydrates Released in Deepwater, Journal of Hydraulic Research, IAHR. October, 48(5), 559-572
Dasanayaka, L. K., and Yapa, P. D. (2009). "Role of Plume Dynamics on the Fate of Oil and Gas Released Underwater," Journal of Hydro-Environment Research, IAHR/Elsevier, March, 243-253.
Xie, H., Yapa, P. D., and Nakata, K. (2007) "Modeling Emulsification after an Oil Spill in the Sea," Journal of Marine Systems, Elsevier, 68 (2007), 489-506.
Chen, F.H, Yapa, P. D., and Nakata, K. (2004). "Simulating the Biological Effect of Oil Spills in Tokyo Bay by Using A Coupled Oil Spill - Toxicity Model," Journal of Advanced Marine Science Technology, AMTEC, Tokyo, Japan, 9(2), 131-155.
Xie, H. and Yapa, P.D. (2003). "Simulating the Behavior and the Environmental Effect of Sediment Plumes from Deepwater Mining," Journal of Advanced Marine Science Technology, AMTEC, Tokyo, Japan, 9(1), 7-35.
Chen, F.H. and Yapa, P.D. (2004). "Modeling Gas Separation From a Bent Deepwater Oil and Gas Jet/Plume," Journal of Marine Systems, Elsevier, the Netherlands, Vol 45 (3-4), 189-203
Zheng, L., Yapa, P. D., and Chen, F.H. (2003). "A Model for Simulating Deepwater Oil and Gas Blowouts - Part I: Theory and Model Formulation" Journal of Hydraulic Research, IAHR, August, 41(4), 339-351
Chen, F.H. and Yapa, P.D. (2003). "A Model for Simulating Deepwater Oil and Gas Blowouts - Part II : Comparison of Numerical Simulations with "Deepspill" Field Experiments", Journal of Hydraulic Research, IAHR, August, 41(4), 353-365
Zheng, L. and Yapa, P.D. (2002). "Modeling Gas Dissolution in Deepwater Oil/Gas Spills," Journal of Marine Systems, Elsevier, the Netherlands, March, 299-309
Chen, F.H. and Yapa, P.D. (2001). "Estimating Hydrate Formation and Decomposition of Gases Released in a Deepwater Ocean Plume," Journal of Marine Systems, Elsevier, the Netherlands, Vol. 30/1-2, 21-32
Zheng, L. and Yapa, P.D. (2000). "Buoyant Velocity of Spherical and Non-Spherical Bubbles/ Droplets," Journal of Hydraulic Engineering, ASCE, November, 852-855