Can I work with simple administrative boundaries instead of sub-catchments? What approach should I take for that?

Humaira,

What WEAP model objects are you referring to? Catchments or demand sites?

If you are referring to catchments, then you may have to populate them manually. If you are using automatic catchment delineation, you can try and create catchments that line up with your administrative boundaries, although the hydrologic boundaries likely do not perfectly line up with the administrative boundaries. To modify the boundaries of each catchment, enter catchment delineation mode, hover the mouse over the outlet point of each catchment (your mouse will transform from a pointer to a cross shape when you are in the right area), then drag the outlet point to change your catchment boundaries.

Please advise me further on how I can help.
-Doug