For the near-shore region around the Lebanon Chemical Company (FF) fertilizer
plant in Selaata, Lebanon, the 3D oceanographical model system ROMS is being
set up to describe the dispersion and spatial distribution of phosphogypsum
sludge emitted by the plant as one of the inputs for a more comprehensive
environmental audit.
The system is implemented as a
web-based client server system to facilitate remote access and shared use.
Nested model domains around a central 5 by 5 km are around the discharge point
within a 12 by 12 km master domain are being defined with varying resolutions
down to 10 m for the near field, 10 or more vertical layers, and the necessary
input data: bathymetry, surface forcings, lateral boundary (flow) conditions,
and emissions are being compiled, analysed, and integrated in a set of data
bases for direct use by mode scenarios.
Local Bathymetry has been prepared by a combination of ETOPO1 global bathymetry data
and local data from the British Admiralty chart 1652 (1:25,000) with more than
100 depth soundings interpolated by the Kriging method.
Meteorological boundary conditions for the ROMS model scenarios are generated by
the 3D prognostic meteorological model MM5 with hourly and 1 km spatial
resolution.
ROMS is being configured for the simulation of "cohesive sediments" to represent
the phosphogysum sludge, with sedimentation and erosion processes considered.
The model describes dispersion, sedimentation, and re-suspension of sediments
on a regular quadratic (horizontal) grid with terrain following vertical
resolution,.
First model results in the master domain for selected dates (September 26/27,
2010) indicate the expected strong logarithmic concentration/deposition
gradients and consequently highly local accumulation of the sludge discharge.
Average concentration across the water column shows a strong vertical gradient
and decreases sharply with distance from the source.
Model results are being made available in standard numerical formats (NetCDF and
CSV) for further processing for environmental toxicology and risk assessment.
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Lebanon Chemical Fertilizer Factory, Selaata: release of phosphogypsum sludge