How to add multiple forums for a single site in Drupal
The Drupal forum module allows creation of multiple forums.  The module allows you to create 'forum containers' (groups of forums) and forums.  

If combined with 'Advanced Forum' and 'Forum Access' modules it should be able to provide you with the facility to create multiple forums and control access by role to specific forums or containers.

The forum containers are actually taxonomy terms so you can customize the URLs for each container by editing the taxonomy term, eg /forum1 /forum2 etc.

To make the URL structure consistent between containers and forum topics, you may also require 'PathAuto' module, and to look at the URL alias patterns. 

For default pattern for forum topics - I use is:

forum/[node:taxonomy-forums:parents:join:/]/[node:taxonomy-forums:name]/[node:nid]


You might find this works better for you if you wish to customize the taxonomy term URLs.

[node:taxonomy-forums:url:path]/[node:nid]


Pattern for forums and forum containers:

forum/[term:parents:join-path]/[term:name]


or perhaps for consistency with custom URLs

[term:parent:url:path]/[term:name]