Impact of Soil on Flooding

Shown are two neighboring fields, one is flooded while one is not. Iowa has recently been affected by major flooding events due to high rainfall and snowmelt. Why are some soils able to absorb rain while others are not? Soil permeability is a measure of how much water can move from the surface into the soil. One thing that influences soil permeability is soil composition. Clay soils have low porosity and do not allow water to percolate as well as soils with more pore space such as those with sand and humus. The cohesion, adhesion and capillary action properties of water affect how water moves through the different types of soil.

• How does the soil from the flooded field differ from the nearby field that does not flood?

• What might influence how much water goes into the soil and how much stays on top?
• What properties of water affect how quickly or how much it can move through the soil?

Students could:

• View the soil from each field in the video and design their own test to determine what types of soil components are porous and permeable. There are many ways to do this such a Porosity and Permeability lab, but students could also come up with a test of their own design. The teacher can provide materials or the students can collect their own soil types outside. 
• Analyze their testing data and make an evidence-based conclusion about what influences soil water holding capacity with an emphasis on how cohesion, adhesion, and capillary action affect water movement. 
• Return to the video and answer why the field next to the school is flooded all the time. This activity could be the beginning of earth science lessons on soil or water.

• Purdue University Extension | Soil Basics: Adhesion and Cohesion: Video showing how cohesion and adhesion affect the movement of water through the soil.
• Purdue University Extension | Soil Basics: Capillary Rise: Video showing how capillary rise affects the movement of water through the soil.
• Wild Earth Lab | Porosity & Permeability: A thorough way to investigate these variables.