The GOC is a little known agency within the Department of Public Safety, but it's an extremely important one. It's there to provide 24-7, 365 awareness on the part of the Government of Canada of any significant event that may require a response by the Government of Canada.
Its first job is simply to be in touch with everything that is happening across the country and to make sure that, to the maximum extent humanly possible, nothing pops out of the blue as a total surprise, such as “We haven't heard of the flood”. That sort of thing you definitely want to avoid.
The GOC then has the capacity to bring all of the federal family together, every department and agency of the Government of Canada that could be relevant to that situation, and make sure they are ready if they are called upon.
They also have the ability to reach out to provinces, territories, municipalities, the private sector, indigenous organizations, auxiliary groups like the Red Cross, and so forth, so that as a situation develops and perhaps gets more serious, you have all of the relevant players quite literally in the same room.