Subbasin Routing to Channel Explanation

[Matthew Lombardo]

Hello everyone,

Note: Please disregard my last emails, I was able to find what I was looking for. 

Can someone explain how the routing works for flow and nutrients into channels? I've added some pictures/screenshots for better explanation. One of my locations for observed nutrient data is in the middle of a channel, shown in the first picture (in that picture water is flowing north/up). Right now I am using the no3_out/outlet as the reference point for the calibration for the channel, but my nitrate loads are much higher than at points upstream. So, I would like to know how the routing into channels works so I can decide if I should use the no3_in for no3_out for my calibration. In SWAT+ Editor under routing units, the only unit connected to my channel, channel 4, is rtu040 (shown in picture 2). When I look under Landscape Units under region, this rtu040 is connected to hru39 (picture 3). Also, in QGIS, it says that the channel is connected to subbasin 5, which is the same area as hru39 (picture 4). Does this mean the flow and nutirents routed into channel 4 from the land is from hru39/subbasin 5? Also how does the routing work, does the flow and nutrients get added up over the channel or just at the outlet? If it just gets added up at the outlet then would the no3_in for channel 4 be equal to no3_out for channel 5 (channel 5 in the only inflow for channel 4, there are no other connections)?

Lastly, under channels it says that channel 4 is 288 ha (picture 5). However, hru39/subbasin5 is only 11 ha. If the only land that is routed to channel 4 11 ha, how is the area of channel 4 288 ha?

Thank you for taking the time and energy to read through this,

Matt Lombardo