Most disasters are not entirely natural.  Human activity can increase their risks and insufficient attention makes their effects more severe.  Look at the sketch closely and find out what causes a flood and what can be done to lessen damage from it.  

1.  Poor farming techniques increases soil erosion.

2.  Deforestation of slopes increases water run-off.

3.  Flash floods are created at the base of mountains due to very heavy rainfall, sometimes made worse by the reduced capacity of the soil to absorb the extra water.

4.  Sediment from erosion settles to the river bottom and gradually raises flood levels in the river.

5.  Overgrazing reduces ground cover and increases water run-off.

6.  Flood plain

7.  Delta

8.  Flood plains in rural areas often attract farmers because of fertility of its land.

A vulnerable house consists of heavy materials stacked in place without a continuous frame for reinforcement.

The house sways with the motion of the earth during an earthquake.

The house cannot bear the growing pressure created by the continuous motion.

The roof and walls of the house collapse.

Lifted from an IEC material produced by the 
Office of the United Nations Disaster Relief Coordinator 
(Palais des Nations, 1211 Geneva 10, Switzerland)