Team 8 - Flooding

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Group 8 is envolved in everything dealing with floods, as their origin and their consecuentions. This group has already prepared information and has elavorated some presentations of this issue.

Floods

What and why?


What is a flood?

A flood is an overflow of an expanse of water that submerges everything under sea level (or under the level of the place where water comes from), from simple land to huge buildings. As an example, during Katrinas huricane there were lots of floods because the city was under the dam level. Some scientits calculated that in the XX century more than 3,2 million people died fot this reason. In Spain this is a really common disaster that affects economy and causes social problems, especially in the Mediterranean coast and in the north of Spain.


What causes floods?

heavy rainfalls.

-This is when rainfall contains a percentage of water much higher than normal.

excess of common rainfalls

-At countries where there is an excess of water, rainfalls have strong consecuences. When the surface can't absorb all the water, it falls and gets stored on the surface what causes the overflowing of rivers and lakes. In Spain scientits register more than 200mm per day every year.

Fusion of snow

-During Springtime the accumulated snow melts; if rainfalls happes at the same time (which is preaty common) floods occur.

Breaking dams

-When a dam breaks (as at the example of Katrinas huricane) all the stored water in the reservoir is released. This is not so unusual, however, nowadays dams are built to be almost imposible to destroy so the main reason dealing with dams is when those have more water that they could contain.

Human activities

-The effects of floods are aggravated by some human activities such as the bad urban planifications of many cities (as New Orleans).


In Spain

<googlemap version="0.9" lat="40.111689" lon="-6.152344" zoom="5">38.565348, -0.065918</googlemap> (the red spot indicates where Lope de Vega school is located) The most affected areas in Spain are:

The north, with more than 300 very dangerous points of possible floods in Pais Vasco, Bilbao, Rentaria, San Sebastian and Gijon. The probability of flooding is high in this places because there is often very high level of rainfalls and the valleys are narrow and deep, with people living too coler so th channels. In this area th risk comes from the typical Mediterranean torrential rains (in a few days rains more than normal). The situation is agravated by the lack of trees and the soil is easily eroded because the water drags many materials withi it. This icreases the volume and its danger. The eastern Pyrenees also have many dangerous point (172 exactly). Floods are caused by mediterranean torrential rains too. However, this area has a great vegetation that protects teh soil from erosion which lowers the damage.