calulate dynamic url according to the zone

I have created a new url for Custom zone of a Site Collection using Set-SpSiteurl. I have a Visual Web Part which displays items in a custom list. Each item in this list has a SPFieldUrlValue. I would like to set the value of Url property of this SPFieldUrlValue based on the user's zone when he creates the item. How do I get the url zone of the site collection? (I don't want to get AAM related url).