-33.918861, 18.423300 I think is the coordinates
Flooding can affect rivers because river flooding causes things to be picked up from the streets and pulled back into the water. So It affects the water quality and if anything dangerous to the fish and water life gets in the water it will mess up their life system. Hope this helped a little bit. :)
The answer would be the 4th option. (Rainwater soaking into the ground). Soil erosion is commonly caused by rainwater soaking into the ground.