Possible Issues in the Water Quality Module in Routing.py

[Aichumei]

I have identified a potential problem in the water quality module.
In the qualityRouting function of the routing.py file, the amount of pollutants transported downstream from each grid is calculated using "channelTransFrac" ( routing.py line 2754-2763) .
However, according to the calculateload module, each grid should have a pollutant load. If a grid does not contain a river, its “channelTransFrac” should be 0 (assuming my understanding of the module is correct). In this case, the load (e.g., domestic discharge) from that grid cannot be transferred to the downstream river. This might result in an underestimation of the pollution load entering the river.
I’m not sure if my understanding is correct.
Thank you for your reply!

[Aichumei]

I reviewed the code again and found that the channelStorage of each grid cell is directly contributed by the total runoff. Does this mean that the presence of a river in each grid cell is not important? Because I did not see any code identifying whether there is a river in the grid cell