Rivers do not run into oceans as rivers do not have legs. Hope this helps :)
The rivers flow increase.
It just happens to be in a small area where there are no waterways.
Water fall
Horfjyf
it gets destroyed
It forms an oxbow lake.
they over flow
no idea. That's what you have youtube for.
Poisoning of the water.
It would effect regions and their agriculture
water inland usually drain into sea through rivers if there is to much rain the rivers and canals gets overflooded