What do the terms porosity and permeability describe in soils?

What do the terms porosity and permeability describe in soils?

• A. Porosity is the amount of open space in a rock or soil; permeability is the ability of a material to transmit fluids.
• B. Porosity is the color of soil; permeability is its texture.
• C. Porosity is how well a rock resists weathering; permeability is rigidity.
• D. Porosity is rainfall rate; permeability is wind speed.

Answer: (A)

Porosity and permeability describe how soils hold and move water. Porosity is the fraction of the soil’s total volume that is open space, which tells you how much water the soil can store. Permeability is the ability of the soil to transmit fluids, which depends on how connected those open spaces are and how large they are. So a soil can have lots of pore spaces (high porosity) but water might not flow through it easily if the pores aren’t well connected (low permeability). Conversely, a soil with well-connected, larger pores tends to allow water to move through it quickly (high permeability). This is why sand often drains quickly (high permeability) while clay can hold water but not allow it to flow easily (low permeability). These ideas are separate from color or texture, and from environmental factors like rainfall or wind speed.

Porosity and permeability describe how soils hold and move water. Porosity is the fraction of the soil’s total volume that is open space, which tells you how much water the soil can store. Permeability is the ability of the soil to transmit fluids, which depends on how connected those open spaces are and how large they are. So a soil can have lots of pore spaces (high porosity) but water might not flow through it easily if the pores aren’t well connected (low permeability). Conversely, a soil with well-connected, larger pores tends to allow water to move through it quickly (high permeability). This is why sand often drains quickly (high permeability) while clay can hold water but not allow it to flow easily (low permeability). These ideas are separate from color or texture, and from environmental factors like rainfall or wind speed.