missing streamflow routing between grid elements

[ThibHlln]

Each grid element is producing streamflow as an outflow of its river_store, but there is no transfer of this streamflow between grid elements. This is because SMART is originally a lumped rainfall-runoff model. However, it has been used in a semi-distributed manner before. So effectively, this version of SMART is only usable for spacedomains with only one grid element until this is resolved.

Four modifications need to happen to make this version of SMART (semi-)distributed:

• its river_store outflow parameter theta_rk needs to be adjusted: it can be done through calibration or through regionalisation – one existing regionalisation is based on the Manning's equation and the use of the river reach length (see Mockler et al., Pathways Project Final Report Volume 4 (2014))
• the flow direction / hydrological connectivity network needs to be given to the open water component
• the river_store needs to take an additional input, that is the upstream routed streamflow
• the open water component needs to use the flow direction / connectivity to determine in the river_store of which grid element to input its outgoing streamflow