Hi Anusha, I remember doing something like this in the past by creating a Dynamic Recipients Source File ( i.e., a WEB-I document with list of all the cities and respective users ) and then Map the fields in this file with the Original Web-I report for publication.
Please refer to the section "11.1.3.2 - Creating a Publication for Dynamic recipients" ( Pages 160 & 161 ) in SAP BO BI 4.1 SP5 User Guide. ( I've attached a copy for your reference ).
Thanks,
Sravan.