In 1889 Johnstown Pennsylvania New York New Jersey PENNSYLVANIA Johnstown Ohio Maryland Other floods are manmade People might build a dam that is not strong enough to hold back water Or a dam can be damaged and break releasing the water behind it received several inches of rain The rain was too much for the South Fork Dam which stood about 12 miles 19 3 kilometers above Johnstown The dam collapsed sending a wall of water down the river The water reached 75 feet 23 meters high and was powerful enough to wash away train locomotives Johnstown was destroyed by the flood and more than 2,000 people were killed The flood in Johnstown destroyed four square miles 10 kilometers of the city’s downtown and 1,600 houses 6
Some floods take a long time to develop A storm might last for days causing rivers and streams to rise over time After a few days the water rises over the banks of the river and floods the land around it Melting snow can also fill rivers and other bodies of water until they flood Meteorologists can often warn people so they can protect their homes and get to safety if they have to Did You Know Sometimes areas that do not have a history of flooding begin to flood Often this is the result of new land development that changes the natural runoff paths 7
Some floods happen very quickly This type of disaster is called a flash flood Flash floods usually happen after a heavy rainstorm or a thunderstorm The rain falls so hard and fast that the ground cannot absorb it Flash floods are very dangerous because people have very little warning or time to escape 8
ROAD FLOODED Did You Know Floods can even happen in the desert The ground in a desert is usually very dry and hard so it can’t absorb rain from a heavy downpour 9
