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.
The people of Egypt used the regular event of the River Nile flood to their advantage. Until 1970, the Nile had flooded every Spring as the mountain snows melted. This flooding of the flat land (floodplains) alongside the river enriched the soils leaving behind rich silt in which crops could be grown.
When the discharge of a river increases, the channel may become completely full. Any discharge above this level will result in the river overflowing its banks and causing a flood. The stage at which the river will overflow its banks is called bankfull stage or flood stage. For example, the flood stage of the Mississippi River at New Orleans is 17 feet. Discharge that produces a stage over 17 feet will result in the water nearing the top of the levee with potential flooding of the city of New Orleans (the top of the levee is actually at 25 feet above sea level).