Factors That Affect Infiltration And Runoff

1. Slope of the Land The steeper the slope, the less infiltration. More runoff occurs. As slope increases, infiltration decreases Indirect Relationship Infiltration Gradient Less steep More steep

. SOIL CHARACTERISTICS This is water that is NOT infiltrating the soil. Instead it is forming runoff. http://www.actewagl.com.au/education/_lib/images/Water/Runoff.jpg

A. Porosity Definition - percent of ___________ in soil open spaces

a. Porosity Particle size alone does not determine porosity Identically shaped samples of increasing particle size will have the same porosity

Porosity and Shape Rounded Vs. Angular Which is more porous? HIGH POROSITY LOW POROSITY

Porosity and Packing Loose Vs. Close Which is more porous? HIGH LOW POROSITY

Porosity and Sorting Sorted Vs. Unsorted Which is more porous? All the same size Different sizes Which is more porous? HIGH POROSITY LOW POROSITY

Which is more porous, a container of: round particles or angular particles tightly packed particles or loosely packed particles c. well-sorted particles or unsorted particles d. large beads or small beads

***Particle size alone does not determine porosity***

b. Permeability The ability to let water pass through it Soils made up of large particles are very permeable and have high infiltration rates For soils to be permeable, the ____________ must be connected * Clay soils absorb water at a very slow rate, small particle size, low permeability (clay has the smallest particle size) Pore spaces

In which soil will water move through more quickly?

A, because the particles are largest PERMEABILITY Which column would allow water to flow through faster and why? A, because the particles are largest

If you join sediment from A and D, PERMEABILITY If you join sediment from A and D, what would happen to the permeability? Why? Decreases because the small particles fill in the spaces

PERMEABILITY Particle Size

Which is more permeable? PERMEABILITY Which is more permeable? a. small particles or large particles b. frozen ground or unfrozen ground

c. Capillarity (Capillary Action) The ability of water to flow upward through soil. Very important to people who grow crops Soils made up of very small particles have the highest capillarity. More surface area for water to cling to

Draw a line to complete the graph below: high Capillarity low small large Particle size

3. Degree of Saturation If the ground is already saturated (fully soaked), then water will more likely __________ runoff

4. Vegetation vs. Land Use Vegetation – little runoff Land Use - paved streets, parking lots – more runoff

Factors Affecting Infiltration: 5.) Ground Temperature—frozen ground limits infiltration of rain and also causes runoff of melting snow http://www.bayjournal.com/images/small/tn-2004-March-1230-img-2.jpg

RUNOFF AND STREAM DISCHARGE FACTORS AFFECTING RUNOFF AND STREAM DISCHARGE Which will result in greater runoff and stream discharge? an area that is vegetated or an area that is barren an area that has a steep slope or an area that is flat ground that is frozen or ground that is unfrozen d. ground that is saturated or ground that unsaturated

Binghamton flood 2011 http://www.youtube.com/watch?v=aqrY7PpeV8s&feature=fvwrel