Flooding

What is a “flood”?

A flood is an overflow of water that submerges land which is normally dry. Floods occur when there is more water in a river, lake, or stream than the body of water can hold. The excess water then floods onto the land. Floods occur frequently when there is excess rain and when the ground is saturated and cannot hold more water. Flooding is the most common natural disaster worldwide. Flooding occurs in rural and urban areas. We are currently experiencing flooding across much of Iowa. Heavy rainfall has contributed to saturated soils and high water levels in streams, rivers, and lakes.

Real Life Events

Show students news clips or documentaries about floods that have occurred, or flooding in general. Ask your students about their experiences with flooding and/or have them interview people who have experienced flooding. Review statistics about damages, losses and environmental impact of flooding.

The New York Times

Poor Land Management Practices Contribute to Flooding

Draining of Wetlands
Wetlands act as natural filters to clean and slow the absorption of water on the land. When wetlands are drained or tiled the water that would otherwise slowly be absorbed by the land flows directly to rivers, streams, and lakes.

Deforestation/Exposed River and Stream Banks
Vegetation holds soil in place and soaks up excess water. When large areas of vegetation are removed water washes over the land (instead of being absorbed) and into rivers and streams. This excess water contributes to the flooding of these bodies of water.

Erosion
Soil erosion due to poor farming practices, improper construction sites, draining of wetlands, and deforestation all contribute to flooding. Excess soil in lakes, rivers, and streams raises the water level (as well as washing away valuable topsoil and muddying the water).

Improper Damming of Rivers and Streams
Improper damming of rivers and streams causes flooding upstream. During periods of excess rain the extra water has no other place to go except out of the river banks and over the land. Improper damming can also cause flooding downstream when excess amounts of water are released to compensate for excess water upstream.


Make a Rain Gauge

Materials:

  • Clear Jar
  • Ruler
  • Paint

Process:

Place jars outside in an open area before it rains. After it has rained measure the amount of rain in each jar.

Create a chart for your class to track the amount of rain you receive at your school. Compare your amounts to your local news station.


Make It Rain in a Jar

Materials:

  • Clear jar
  • Plate
  • Hot water
  • Ice cubes
  • Index cards

Process:

Pour about two inches of very hot water into the glass jar. Cover the jar with the plate and wait a few minutes before you start the next step. Put the ice cubes on the plate.

Explanation:

What happens? The cold plate causes the moisture in the warm air, which is inside the jar to condense and form water droplets. This is the same thing that happens in the atmosphere. Warm, moist air rises and meets colder air high in the atmosphere. The water vapor condenses and forms precipitation that falls to the ground.


Aquatic WILD activities to use while studying flooding:

To Dam or Not to Dam- portray individuals representing differing perspectives and concerns related to a complex issue

Watershed- describe the characteristics of watersheds, discuss the role of watersheds in providing wildlife habitat as well as human habitat, and give examples of watershed conservation

Wetland Metaphors- describe the characteristics of wetlands and evaluate the importance of wetlands to wildlife and humans

What’s in the Water?- identify major sources of aquatic pollution and make inferences about the potential effects of a variety of aquatic pollutants on wildlife and wildlife habitat

Where Does the Water Run?- design and implement a field investigation involving relationships between levels of precipitation, runoff, and percentage of impervious ground cover

 

Helpful Links

The Iowa Flood Center

The Top 5 Iowa Floods

The National Weather Service- Flooding in Iowa

BrainPop: Floods

Weather WizKids: Rain & Floods

Weather WizKids: Flood Safety

 

Cross-reference to these units: