I would like to know if someone knows whether there are IT solutions (websites etc) that help with meeting interdisciplinary researchers from local academic institutions (socal).
If you really want them local, the best social network is actually being social.
You can either attend conferences and university events in your city, attend seminars at other departments (some are announced in their webpages), or just send a series of polite emails to researchers working in thins you want. Just list the departments that may be doing something you like, browse their personnel, and skim their last publications to see if your research interests may be aligned.
In my case, through my universities intramural cricket league! Seriously, getting to know academics in a social context not directly related to work is an excellent way to find people to work with, and if they are people you get on well with, that makes the academic collaboration more enjoyable and productive. Most universities have social clubs and societies (and e.g. language courses) that are open to staff.
I would suggest you try finding researchers on Academia.edu. Generally, you will find a whole host of researchers who have similar research interests and who are willing to collaborate. You also might try to find email or snail mail addresses of researchers you are already familiar with in order to establish links with them. If you don't attend conferences and network, I believe the above are viable options you should consider.