Wetlands

A wetland is a complex hydrological unit with features including a connection between a water source and a water body or storage. Multiple storages can be interconnected to form a complex system. In some systems, wetlands consist of several storages connected using wetland links. In others, a wetland can connect directly to a main river channel. Wetlands may have ecological, recreational, cultural or consumptive requirements and thus behave in a similar way to some functions of the water user node.

Wetland Hydraulic connector node

The hydraulic connector connects wetlands directly to the main river network (ie. not at a storage). This node distributes flows between the main river system and the wetland system. It represents a boundary condition for the connected wetland cluster with a configured reduced level (surface water elevation) versus flow rate relationship.

Figure 1. Hydraulic connector node

Wetland Link

This link is used to connect storages in a wetland, or a wetland to a river and use a hydraulic model. There are different types of wetland link to reflect differences in hydraulic properties - eg. conveyances, weirs, pumps and culverts. Wetland links can be either regulated or unregulated. This link is both uni- and bi-directional and net evaporation, groundwater and other fluxes are not modelled.

Essentially the wetland storage models a pool of water connected to one or more wetland links. Functionality of standard storage nodes (which have an inlet and one or more outlets connecting to standard links) is retained, as well as the ability to model wetland link connections.

Storage volumes, levels and flows are first estimated using cell model equations, then recalculated using the standard Source storage model. The aim of this additional storage model run is to interface between the cells model and the rest of the river system model. When running the storage model, accumulated wetland link flows to/from the storage are treated as a lateral flux – ie in the same way as seepage and net evaporation. This has the same effect as treating the wetland link as an inflow, or a priority zero outlet (ie. an outlet with higher priority than all others). Storage releases down standard links are taken into account in cell model storage and wetland link calculations, but these are an approximation based on combined outlet capacity and orders. Outlet path priority is not considered for this purpose.

Once a wetland link has been specified, double click it to configure it using the wetland link feature editor (Figure 8).