Sanjiangyuan National Natural Reserve (source of 3 rivers)

Hi! I would like to visit the Sanjiangyuan National Natural Reserve, to see the sources of the Mekong, Yellow and Yantze rivers. I am struggling to find information on how to go about this - do I need a special visa (except for Chinese tourist visa), where should my base be, do I need a guide, and how exactly should I go to Sanjianyuan?

Any help would be appreciated.

Thanks!
Petro