Hello

an irrigated area of 5000 ha, I put it in WEAP as a Demand site or a catchment

thank you

WEAP has flexibility here - you can do it either way, and it depends on your priorities.

To model your irrigated area as a demand site, see the WEAP's tutorial's WEAP in One Hour/Entering Elements into the Schematic/Section 9. Create an Agricultre Demand Site.

It is more complicated to model an irrigated area as a catchment, but also gives you a lot more control. See the Hydrology section of the WEAP tutorial, it will guide you through the process.

I recommend reading through both sections and decided which representation works better for the analysis purposes you need.