Rainfall Simulator Illustration Title Water Quality
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picture showing a pan which has its left side showing a lot of soil erosion and the right side showing a lot less soil erosion because of the wheat straw that is present on the right sideNotice the large amount of soil splashed onto the left flume in this picture.  A lot of soil is being removed by the water flowing across the soil surface in this pan.  There is also some soil loss from the pan on the right, but it is a lot less, since soil is visible on the flume.  The only treatment difference in these two pans is the amount of wheat straw that is on the soil surface.  


picture showing the two buckets of water we got from the above process showing that the left pan bucket has more soil that the right oneHolding these two buckets up to the light really shows the difference in the amount of soil that is lost to erosion when the surface is left unprotected.  The other obvious difference in the two buckets is the difference in total amounts of water runoff.  The pan that is protected by residue maintains a higher infiltration rate.  Remember this relationship:

Runoff  =  Rainfall rate - Infiltration rate

Since the rainfall rate is constant, a lower infiltration rate results in a higher amount of  runoff.  That's what you can see in the buckets.  More water (as well as more soil) has runoff from the unprotected soil.


shows the above obtained water bucket showing that the left bucket has a lot of soil sediment than the right oneThis picture was taken four days after the demonstration.  The water was left undisturbed for this entire time, yet the suspended solids (mostly clays and some organic matter) have remained in the water.  The bucket on the left, which came from the unprotected soil, has nearly a quarter inch of sediment sitting on the bottom, while the one to the right, which was protected by wheat straw, has very little sediment on the bottom. 

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