From deep-sea to the beach: a holistic approach to oil and
HNS spill risk management
Fernandes R1, Leitão, P2, Braunschweig, F3, Neves R1
1MARETEC
– Instituto Superior Técnico – Universidade de Lisboa
2 Hidromod Lda.;
3 Action Modulers
INTEGRATION IN MOHID
THE PROBLEM
Deep offshore drilling; oil and chemical mega-tankers; more than 2000
chemical substances transported by the sea: these are just some examples of
new emerging challenges in the context of spill prevention and response
activities. The problems are quite different, but the consequences of spill
incidents can still converge to common problems: history showed that if
something goes wrong offshore, nearshore, in deep-sea or shallow waters, in a
chemical or oil tanker - the environment, public health or economy are always
subject to some risks.
Nevertheless, using several different modelling tools adapted to each kind of
scale, system or spill pollution type potentially reduces response effectiveness,
avoiding integrated approaches, adapted to the needs and technological
possibilities nowadays.
MOHID
InterfaceWaterAir
WAVES
This paper intends to answer a different number of recent and upcoming
questions regarding preparedness and response to oil and HNS spills,
supported by a common modelling system (MOHID) capable of integrating
different processes, scales and environments.
A wide range of scales (in both aquatic and
land environments) requires the consideration of
the corresponding transport processes and of
interactions between scales. MOHID is a publicdomain open-source system, developed
following a modular structure combined with
object oriented programing (Neves, 2013).
Lagrangian
Oil, HNS, Jet
www.mohid.com
mohid.codeplex.com
Sediment
MOHID (www.mohid.com) is an environment
modelling system dealing with transport and
with biogeochemical transformation processes
in complex geometries. It was developed to be
used by researchers and by professionals and
to be applicable to a large range of scales and
physical conditions. Researchers require tools
able to test hypotheses and compare options.
Professionals require efficiency for quick results
production.
Hydrodynamic
Turbulence
GOTM
BENTHOS
MODELLING APPROACH
Lagrangian Approach:
Oil and HNS modelling components are integrated on MOHID lagrangian transport
module, where simulated pollutants are represented by a cloud of discrete particles (or
super-particles) advected by wind, currents and waves, and spread due to random
turbulent diffusion or mechanical spreading.
Offline / Online:
This model has the ability to run integrated with hydrodynamic solution, or independently
(coupled offline to metocean models), being this last one the commonly adopted option
for integration in the developed operational tools (to reduce computation time, taking
advantage of metocean models previously run).
HNS modelling component:
The freshly new chemical spill module component implemented in MOHD estimates the distribution of chemical on
water surface, shorelines, atmosphere, water column, sediments and seabed. Spilled mass is tracked through phase
changes and transport. Model tracks separately evaporated or volatilized particles, floating chemical, entrained droplets
or suspended particles of pure chemical, chemical adsorbed to suspended particulates, and dissolved chemical.
3D underwater view of a cloud of
particles simulating a surface chemical
spill
Multi-mesh solution:
MOHID lagrangian transport module includes a multi-mesh functionality, allowing particles
to move along different model domains / grids. The main advantage on this approach is
the possibility of using simultaneously multiple high resolution models when and where
available, together with other models with lower resolution, in the same spill simulation. In
this way, one can take advantage of several different operational modeling systems, using
them in an integrated fashion. MOHID lagrangian computes the needed interpolations onthe-fly, and limit these interpolations to a specific spatial area where lagrangian particles
are present (Fernandes, 2013).
This integrated and holistic approach allows MOHID to simulate spills from deep sea
blowouts and transport it to a beach in the same simulation.
A cloud of particles being advected across three
horizontally aligned grids. The grids order of priority is the
following: blue, red and grey
(source: Janeiro et al., 2014)
APPLICATIONS AND CASE STUDIES
Several different environments, processes and user interfaces have been tested with MOHID lagrangian component along the last decade. Some of these case studies using oil & inert spill module are presented.
Prestige accident (after sinking):
Comparison of the forecasted position
with MOHID (coloured spots) with
overflight observed position (black
circles)
(source: Carracedo et al., 2006)
Operational oil spill scenario simulated during the fuel diesel removal
operations from the Costa Concordia ship
(source: Janeiro et al., 2014)
50 um (0.05 mm)
Blowout simulations in Caribbean Coast (Colombia): Particle depths with different oil droplet diameters. 3D
(above) and XY (below) views
source: Leitão et al., 2013
References:
Tagus estuary (Lisbon): Drifting buoys position (represented by
markers with color scale representing time after release) vs.
MOHID floating particles (in one instant) considering different
turbulent diffusivities (represented by polygons with different
colors)
(source: Fernandes et al., 2013)
ARCOPOL / Aquasafe Oil Spill Simulator:
Oil spill simulation from satellite-detected oil slick
(Polygons from EMSA’s CLEANSEANET service can be imported to this
operational system and used as initial spill position)
ARCOPOL / MOHID Studio’s Dynamic Risk Tool:
Shoreline contamination risk from ship-source oil spills along Portuguese
continental shelf
(this tool is able to compute realtime and historical risks using space-time variable
data layers as metocean forecasting systems, AIS information, and oil spill model
results based on ship trajectories)
Acknowledgements: This research has been partially supported by ARCOPOL PLATFORM (contract nr. 2013-1/252) - funded by EU Atlantic Area)
Carracedo, P., S. Torres-López, M.Barreiro, P. Montero, C.F. Balseiro, E. Penabad, P.C. Leitão and V. Pérez-Munuzuri (2006). Improvement of Pollutant Drift Forecast System Applied to the Prestige Oil Spills in Galicia Coast (NW of Spain): Development of an Operational System. Marine Pollution Bulletin, 53: 350360
Fernandes, R., Neves, R., Viegas, C., Leitão, P. (2013). Integration of an oil and inert spill model in a framework for risk management of spills at sea - A case study for the Atlantic area. 36th AMOP Technical Seminar on Environmental Contamination and Response. Halifax, Nova Scotia, Canada. pp. 326-353.
Janeiro J, Zacharioudaki A, Sarhadi E, Neves A, Martins F. (2014). Enhancing the management response to oil spills in the Tuscany Archipelago through operational modelling. Marine Pollution Bulletin, 85(2): 574-589
Leitão, P C, Malhadas, M, Ribeiro, J, Leitão, J, Pierini, J, Otero, L.(2013). An overview for simulating the blow out of oil spills with a three-dimensional model approach (Caribbean Coast, Colombia). Ocean modelling for coastal management – Case studies with MOHID. M. Mateus & R. Neves (eds.), IST PRESS, pp.97 - 115
Neves, R. The MOHID Concept. (2013). Ocean modelling for coastal management – Case studies with MOHID. M. Mateus & R. Neves (eds.), IST Press, pp. 1-11