Flooding © The GlobalEd 2 Project Photo credit: K.M. Chaudary, National Geographic Flooding in Pakistan displaced 20 million people

Definition of Flooding Stage – Term that refers to the height of a river (or any other body of water) above a locally defined elevation. This locally defined elevation is a reference level, often referred to as datum. © The GlobalEd 2 Project

Definition of Flooding (continued) 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. © The GlobalEd 2 Project

Flooding Today (Example): The flood stage of the Mississippi River at New Orleans 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 23 feet above sea level). © The GlobalEd 2 Project

Causes of Flooding Heavy rainfall (in a short period of time), sudden or heavy snow melt, and dam or levee failure Rainfall that is heavier than normal in a particular area, with low evaporation and infiltration (how readily water can be absorbed by the soil), causes high and swift water runoff. © The GlobalEd 2 Project

Is flooding evidence of global warming? Some scientists believe that flooding is evidence of global warming – why? –polar and arctic areas are getting warmer, which releases more water, and increases global sea levels –Gradual melting of Greenland ice sheets © The GlobalEd 2 Project

What do you think? Is flooding evidence that global warming is “real”? How does flooding impact water scarcity? Hint: Can people drink salt water (sea level rise) or water contaminated with fertilizer (flooding of agricultural land)? © The GlobalEd 2 Project