Water quality processes are modelled in links and for certain node types which have storage associated with them (see Nodes SRG for more information on these)- SRG). Most node types have no storage and at these the mass balance of each water quality constituent being modelled is maintained with no decay or deposition processes.
Two approaches are provided for routing constituent movement through a reach. The first approach assumes the constituent is fully mixed within a reach. This approach can be appropriate where the user is interested in monthly or annual loads. A particle tracking method that is also provided routes the constituent at the velocity of flow (Close, 1996). This method is more accurate and is suitable where the user is interested in concentrations or loads at smaller scales. More information on these methods is available via Routing Type SRG.
A number of options are available for representing in-stream water quality modification processes in links and storages:
- There are two general models that can act on each constituent in the river, in a manner similar to the processing of each constituent by filter models. These comprise a decay model (see Decay SRG) and modelling , in links only, modelling of surface water-groundwater exchange fluxes (see Flux SRG).
- Simple storage nutrient and sediment deposition models have also been provided. More information on these models is available via Decay SRG.
...