As previously stated in Rivers SRG, Source uses a link-node structure to represent river systems for modelling. Water quantity processes modelled comprise flow routing in links and a large range of processes modelled at nodes.
Two flow routing methods are available to model travel time and attenuation in links: pure lag or translation, and a generalised streamflow storage routing method, which can represent linear, non-linear, and variable parameter Muskingum routing (details on all these are available in Link storage routing - SRG). In the routing algorithm, river water (in-bank flow) fills the dead storage in a reach first before propagating through the reach. Overbank flow is considered for modelling interactions between surface water and groundwater. The surface water-groundwater (SW-GW) interaction component in Source (see Groundwater Analytical Tool - SRG for details) is integrated into the river network through links. (Extracted from Welsh, et al, 2013, with adaptations to suit the needs of the SRG.)
Source has a number of node types available and these are listed in Nodes - SRG, together with an overview of the processes modelled at each node type and references to where details on each node type can be found.
Welsh, W.D., Vaze, J., Dutta, D., Rassam, D., Rahman, J.M., Jolly, I.D., Wallbrink, P., Podger, G.M., Bethune, M., Hardy, M.J., Teng, J., Lerat, J. (2013) An integrated modelling framework for regulated river systems. Environmental Modelling & Software, 39: 81-102.