POINT SOURCE UNITS

[Mario Fomaca Jr]

Hi everyone,
I’m struggling to understand the correct units for point‑source inputs in SWAT+, and I’d appreciate some help from anyone who has dealt with this before.

I’m working with phosphorus loads, but my original data is annual. To create a monthly time series, I simply divided the annual value by 12. I’m not sure if this is the correct approach or if SWAT+ allows using an annual time series directly for point sources.

Besides, the documentation says the units are m³ for “Volume of water” and kg for “Load”. My initial assumption was that I should enter the total monthly volume and total monthly load.

However, even when I select the monthly time‑series option, the interface still asks for day/month/year. And when I run the model, the recall_mon output shows the values I entered multiplied by the number of days in the month.

So now I’m confused about two things:

1. Should the monthly point‑source file contain average daily flow (m³/day) and average daily nutrient load (kg/day), with SWAT+ multiplying by the number of days automatically?
2. If my data is originally annual, is dividing by 12 acceptable, or is there a better way to input annual point‑source data directly?

See example:

Any clarification or examples would be extremely helpful.

Thanks,
Mario