Modelling Software General
1. The modelling software shall be fully 3-dimensional capable of accurately simulating the stratified condition, salinity transport, and effect of wind and tide within the model area.
2. The modelling software shall consist of hydrodynamic, water quality and particle dispersion modules. The hydrodynamic and water quality modules shall have been proven with successful applications locally and overseas.
3. The hydrodynamic and water quality modules shall be strictly mass conserved at all levels.
4. The assessment and modelling tool for spill events should be quantitative with proven applications locally or overseas.
1. The models shall be properly calibrated and validated before its use in this study in the area including the Junk Bay, Eastern Buffer and eastern part of Victoria Harbour Water Control Zones under the WPCO, with the field data collected from:
* Further Development of Tseung Kwan O Feasibility Study (2003)
* Hydraulic and Water Quality Studies in Victoria Harbour (1987)
* Update on Cumulative Water Quality and Hydrological Effect of Coastal Development and Upgrading of Assessment Tool (1998)
* EPD¡¦s routine monitoring data
* Tidal data from HK Observatory, Macau and relevant Mainland Authorities.
2. Tidal data shall be calibrated and validated in both frequency and time domain manner.
3. For the purpose of calibration and validation, the model shall run for not less than 15 days of real sequence of tide (excluding model spin up) in both dry and wet seasons with due consideration of the time required to establish initial conditions.
4. In general the hydrodynamic models shall be calibrated to the following criteria :
|
Criteria |
Level of fitness with field data
|
|
|
Ÿ |
tidal elevation (rms) |
<8% |
|
Ÿ |
maximum phase error at HW and LW |
<20 minutes |
|
Ÿ |
maximum current speed deviation |
<30% |
|
Ÿ |
maximum phase error at peak speed |
<20 minutes |
|
Ÿ |
maximum direction error at peak speed |
<15 degrees |
|
Ÿ |
maximum salinity deviation |
<2.5 ppt |
1. The suspended solids model for assessing impacts of sediment loss due to marine works shall incorporate the processes of settling, deposition and erosion. Contaminant release and DO depletion during dredging and dumping shall be simulated by the model.
2. The water quality modelling results shall be qualitatively explainable, and any identifiable trend and variations in water quality shall be reproduced by the model. The water quality model shall be able to simulate and take account of the interaction of dissolved oxygen, phytoplankton, organic and inorganic nitrogen, phosphorus, silicate, BOD, temperature, suspended solids, air-water exchange, E. coli., contaminant release of dredged and disposed material, and benthic processes. It shall also be able to simulate salinity. Salinity results simulated by hydrodynamic models and water quality models shall be demonstrated to be consistent.
3. The models shall at least cover the Hong Kong waters, the Pearl Estuary and the Lema Channel to incorporate all major influences and hydrodynamic and water quality. A fine grid model can be used for detailed assessment of this study. It shall cover at least the TKO Bay, eastern Victoria Harbour up to Tsim Sha Tsui and the Tathong Channel.
4. In general, grid size at the area affected by the project shall be less than 400m in open waters and less than 75m around sensitive receivers. The transverse grid size at the two drainage channels shall be less than 35m. The grid schematisation shall be agreed with EPD. All models shall either be dynamically linked to a far field model or form part of a larger model by gradual grid refinement.
1. The assessment shall include the construction and operation phases of the project. Scenarios to be assessed shall cover the baseline condition and scenarios with various different options proposed by the Applicant in order to quantify the environmental impacts and improvements that will be brought about by these options. Corresponding pollution load, bathymetry and coastline shall be adopted in the model set up.
2. Hydrodynamic and water quality models shall be run for (with proper model spin up) at least a real sequence of 15 days spring-neap tidal cycle in both dry season and wet season.
3. The results shall be assessed for compliance of Water Quality Objectives. Any changes in hydrodynamic regime shall be assessed. Daily erosion / sedimentation rate shall be computed and its ecological impact shall be assessed.
4. The impact on all sensitive receivers including the application of bacterial dispersion module shall be assessed.
5. Cumulative impacts due to other projects, activities or pollution sources within a boundary to the agreement of EPD shall also be predicted and quantified.
6. All modelling input data and results shall be submitted in digital media to EPD.