Once a person is affected by a dengue virus, the platelets can no longer âactivateâ itself. So whenever there is damage, the platelets cannot form the mesh structure and the blood flows out of the vessel. As blood flows out, so does the platelets. This causes the platelet count to fall drastically. The blood that flows out causes internal. and external bleeding and leads to a haemorrhage.
1 Today, the Aswan Dam keeps the Nile from flooding modern cities. 2  The Ancient Egyptians called the Nile the Aur, which means black and comes from the black soil. 3  The Egyptians measured the height of the annual flood using a Nilometer.
Causes of flooding. A flood occurs when a river bursts its banks and the water spills onto the floodplain. Flooding tends to be caused by heavy rain: the faster the rainwater reaches the river channel [river channel: The part of the river that holds the water. ] , the more likely it is to flood.