wouldn,t sea levels rise anyway asthe rivers are always flowing in to the oceans?

Answer 1

Probably you should consider where the water in the rivers is coming from?

The only way the rivers can get water is from the rain and snow, and that comes from clouds. The clouds come from water evaporated from the sea. So, the amount going back to the sea and the amount being taken out of the sea are roughly equivalent.

The only thing that messes up the equation is, how much water than rains on the land will stay there as permanent ice. Glaciers, like in Greenland, hold a lot of old rain and snow water that got frozen many thousands of years ago. So if they melt, that old rain will at last return to the sea, so the sea will be a little higher --- suppose it is only 1% higher --- since the sea is roughly 10,000 feet deep on average, then 1% rise would be 100 feet.

Get out your rubber boots!

Answer 2

The atmosphere continually picks up water moving it around and depositing on mountains where it melts and runs down again as water.
If the polar ice caps melted you could suppose the sea levels may rise.
It may take a long time before we can make an accurate assessment of what is really going on.