Government land and personal use

Does anyone know where people the use gov't land ,gain that right?Do they just squat until the government tell them to leave?
I have always been under the impression,that in Thailand,the land in front of a business or property is the ''domain'' of the property owner.Businesses charge people rent that set up shop in front of their store property,for example!

In NK the government built a beautiful looking promenade in front of the Tha Sadet market and area on the waterfront,the businesses there use the area to put up tables,tend to the gardening and cleanup etc,treating it as there domain.

Floating resturants, Fish farming rigs and attendant storage and living salas pop up along the river banks,who gives permission for this or regulates it?
Where would one go to get that information?

What,no one has any experience,knowledge or ideas?

It may pay to contact the operators of Mutmee Guest House, with their floating restaurant etc, they may be able to throw some light on the subject.

nice Bangkok Post article covering "land encroachment".. http://www.readbangkokpost.com/easybusinessnews/agriculture/forest_encroachment_and_land_t.php