DISPER software: environmental risk assessment

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Algorithms IV · environmental risk assessment · software

The Vertical Term

The Vertical Term (V) accounts for the vertical distribution of the Gaussian plume. It includes the effects of source elevation, receptor elevation and plume rise. In addition to the plume height, receptor height and mixing height, the computation of the Vertical Term requires the vertical dispersion parameter (sig_z). The Vertical Term without deposition effects is then given by:

V= exp{-0.5 [(z_r-h_e)/ sig_z]²}+exp{-0.5 [(z_r+h_e)/ sig_z]²}+

+{exp[-0.5 (H₁/sig_z)²]+exp[-0.5 (H₂/sig_z)²]}_i=1,2,...+

+{exp[-0.5 (H₃/sig_z)²]+exp[-0.5 (H₄/sig_z)²]}_i=1,2,...(34)

where:

h_e = h_s + Dh

H₁ = z_r - (2iz_i - h_e)

H₂ = z_r + (2iz_i - h_e)

H₃ = z_r - (2iz_i + h_e)

H₄ = z_r + (2iz_i + h_e)

z_r = receptor height above ground (flagpole) (m)

z_i = mixing height (m)

The infinite series term in Equation {} accounts for the effects of the restriction on vertical plume growth at the top of the mixing layer. This equation assumes that the mixing height in rural and urban areas is known for all stability categories.

The model make the following assumption about plume behavior in elevated simple terrain (terrain that exceeds the stack base elevation but is below the release height):

• The plume axis remains at the plume stabilization height as it passes over elevated or depressed terrain.

• The mixing height is terrain following.

• The wind speed is a function of height above sea level.

Thus, a modified plume stabilization height h_e_ is substituted for the effective stack height h_e in the Vertical Term given by Equation (1-50). For example, the effective plume stabilization height at the point x, y is given by:

h^’_e=h_e+z_s-z_(x,y) (35)

where:

z_s= height above mean sea level of the base of the stack (m)

z_(x,y)= height above mean sea level of terrain at the receptor location (x,y) (m)

It should also be noted that, the ISC models truncate terrain at stack height as follows: if the terrain height z - z_s exceeds the source release height, the elevation of the receptor is automatically chopped off at the physical release height. The user is cautioned that concentrations at these complex terrain receptors are subject to considerable uncertainty.

The Decay Term (D)

The Decay Term is a simple method of accounting for pollutant removal by physical or chemical processes. It is of the form:

D=exp(-psi x/u_s) for psi > 0 (36)

D=0 for psi = 0 (37)

where:

psi= the decay coefficient (s^-1) (a value of zero means decay is not considered)

x= downwind distance (m)

For example, if T_1/2 is the pollutant half life in seconds, the user can obtain y from the relationship:

psi=0.693/T_1/2 (38)

The default value for psi is zero. That is, decay is not considered in the model calculations unless y is specified. However, a decay half life of 4 hours (y = 0.0000481 s^-1) corresponds to SO₂ when modeled.

environmental risk assessment

DISPER software solutions: This application has been used in great number of environmental reports, noise courses and noise studies in the last years. We currently have users in more than 10 countries. Noise reports in England:

Lancashire - environmental risk - environmental risk management - management risk credit -

Worcestershire - environmental risk evaluation -

Cambridgeshire - environmental risk communications -

Buckinghamshire - guidelines for environmental risk assessment and management -

Gloucester - environmental risk manager - environment agency flood risk assessment - environmental risk analyst -

Hereford - environmental risk assessment process - environmental risk management consulting - guidelines for environmental risk assessment -

Inverness - environmental risk management authority - environmental risk assessment and management - environment and risk -

Kingston upon Hull - environmental risk factors - environmental risk communication - environmental risk assessment report -

Lancaster - environmental risk managment - environmental risk managers - environmental risk analysis -

Leeds - business environmental risk - environment risk assessment - corporate environmental risk management -

Leicester - environment risk management - environmental risk factor - environmental risk survey -

Lichfield - risk free environment - environment risk - environmental risks -

Lincoln - centre for environmental risk - environmental risk solutions - define environmental risk -

Lisburn - operational risk - risk analysis - credit risk -

Liverpool - environmental risk assessment - environmental insurance - risk assessment -

Manchester - environmental risk assessment training - high risk environment - business risk -

Newcastle upon Tyne - human and environmental risk assessment - environmental health risk - environmental risk definition -

Newport - environment at risk -

Newry - environmental impact assessment - strategic environmental assessment - environmental risk assessment -

Warwickshire - environmental risk management inc - managing environmental risk - global environmental risk -

Shropshire - environmental services - environmental assessment - environmental site assessment -

Northamptonshire - environmental monitoring and assessment - phase i environmental assessment - canadian environmental assessment act -

Wiltshire - ontario environmental assessment - environmental assessment report - bc environmental assessment -

Durham - phase ii environmental site assessment - environmental assessment form - ontario environmental assessment act -

Nottinghamshire - bc environmental assessment office - environmental assessment association - environmental assessment agency -

Somerset - integrated environmental assessment - institute of environmental assessment - environmental monitoring assessment -

Derbyshire - what is environmental impact assessment -

Essex - phase one environmental assessment - environmental assessment services - institute for environmental assessment -

Norwich - phase i environmental site assessment - phase 1 environmental site assessment - environmental assessment act

Nottingham - environmental planning and assessment act -

Oxford - federal environmental assessment - environmental assessment training - environmental assessment guidelines -

Peterborough - integrated environmental assessment and management - environmental planning assessment act - environmental impact assessment training -

Plymouth - environmental modeling and assessment - environmental management and assessment - municipal class environmental assessment -

Portsmouth - environmental health assessment - environmental impact assessment directive - national center for environmental assessment -

Preston - strategic environmental assessment directive - nepa environmental assessment - environmental impact assessment regulations 1999 -

Ripon - environmental health risk assessment - environmental assessment regulations - canada environmental assessment -

Salford - environmental impact assessment scotland -

Derry - environmental impact assessment guidelines - environmental planning & assessment act - town and country planning environmental impact assessment -

Dundee - environmental planning and assessment regulation 2000 - office of environmental health hazard assessment - environmental impact assessment process -

Durham - environmental assessment process - class environmental assessment -

Edinburgh - institute of environmental management and assessment - assessment of environmental effects -

Ely - environmental impact assessment review - environmental impact assessment eia - environmental planning and assessment regulation -

Exeter - environmental impact assessment report - phase 1 environmental assessment -

Glasgow - environmental impact assessment regulations - environmental assessment office - netherlands environmental assessment agency -

Salisbury - canadian environmental assessment - environmental planning and assessment act 1979 - canadian environmental assessment agency -

Sheffield - environmental impacts assessment - environmental impact assessment reports - stochastic environmental research and risk assessment -

St Albans - environmental life cycle assessment - environmental assessment tool - baseline environmental assessment -

St David's - draft environmental assessment - electronic product environmental assessment tool - environmental monitoring and assessment journal -

Stirling - environmental quality assessment - environmental impact assessment jobs - environmental and social impact assessment -

Stoke-on-Trent - environmental impact assessment scotland regulations 1999 -