1999-029 - Laserfiche WebLink

Home Browse Search

13 A.5 Finf ish and ShellFish Transport The EFDC code includes the capability of simulating the transport and fate of various life stages of finfish and shellfish. Mortality, predation, toxicity and swimming behavior are simulated in addition to advection and diffusion by the ambient flow. Organism age and ambient environment queued vertical and horizontal swimming and settling is simulated. • Environmental queues include light intensity, temperature, salinity and tidal phases. A.7 Near Field Lischarge Dilution and Mixing Zone Analysis In addition to the far field transport and fate simulation capability incorporated into the EFDC code's water quality and toxic contaminant modules, the code includes a near field discharge dilution and mixing zone module. The near field model is based on a Lagrangian buoyant jet and plume model (Frick, 1984; Lee and Cheung, 1990) and allows representation of submerged single and multiple port diffusers and buoyant surface jets. The near field model provides analysis capabilities similar to CORMIX (Jirka and Doneker, 1991; Jirka and Akar, 1991) while offering two distinct advantages. The first advantage is that a more realistic representation of ambient current and stratification conditions. This representation is provided directly by the EFDC hydrodynamic module, is incorporated into the analysis. The second advantage is that multiple discharges and multiple near field analysis times may be specified to account for varying ambient current and stratification conditions. For example, the analysis of ten discharges under six ambient conditions each would require 60 executions of CORMIX, while the entire analysis of the 60 situations would be produced in a single EFDC simulation. The near field simulation may be executed in two modes. The first mode provides virtual source information for representing the discharges in a standard EFDC far field transport and fate simulation. The second mode directly couples the near field and far field transport during simultaneous near and far field transport and fate simulation modes using a virtual source formulation. A.7 Spill Trajectory and Search and Rescue Simulation In addition too the Eulerian transport equation formulation used for far field analysis and the Lagrangian jet and plume module used for near field analysis, the EFDC code incorporates a number of Lagrangian particle transport formulations based on an implicit trilinear interpolation scheme (Bennett & Clites, 1987). The first formulation allows the release of neutrally buoyant or buoyant drifters at user specified locations and times. This formulation is useful in simulating spill trajectories, search and rescue operations, and oceanographic instrument drifters. The second formulation releases drifters in each three-dimensional model cell at a specified sequence of times and calculates the generalized Lagrangian mean velocity field (Andrews and McIntyre, 1978) relative to a users specified averaging interval.