Friday, August 20, 2010

Creek Obstructions

If water flowed downhill without encountering resistance, it would travel in a straight line. Some forms of resistance are obvious. A fallen tree that can’t be moved by the water, must be bypassed. I discussed this fallen tree back in the winter and it is still redesigning this section of creek.

The wider the creek gets, the slower the water flows. Eventually, the channel bypassing the tree will be large enough to accommodate all of the water flow and the creek will stop getting wider. The tree will gradually decompose and will finally be carried down stream. When that happens, this wide area will tend to slow the water and the temporary hole that has been created will be filled with deposited gravel.

Obstacles like fallen trees are easy to spot, but they are not the only type of resistance acting on the flowing water. Water is attracted to itself and other objects. Water flowing down the creek tries to hold on to the rocks, roots and soil of the stream bed. This slows the speed of water going down the channel and the result is exactly what you see when you have a slow moving car in heavy traffic; first there’s a back up and then people start to pass. Water not in contact with the stream bed is not affected by the strong attraction and can move at a faster speed. The faster moving water begins to pass the slower water with some going over the top and some trying to go around. The result is a stream that tries to change its shape.

We’ll stop here for a little follow-up on the perched island of vegetation. There seem to be a fewer number of plants surviving in this hanging mass of flood debris. Those that are left seem to be doing well. I suspect the Hog-Peanut Vine of getting its roots into the actual creek bank.

The creek banks themselves become obstacles. Masses of roots hang free on this curve and provide a buffer between the soil and the rushing water.

Of course, a big chunk of rock posing as a hill is a pretty insurmountable obstacle. The result has been a long stretch of creek with a wide gravel bottom. The gravel in this area is constantly being picked up and carried downstream, but the loss is usually followed by an equal amount of new deposition, so the gravel stretch is fairly stable even though it’s not always the same gravel.

It’s fun to watch the creek change as it encounters new obstacles. The creek changes constantly, but it’s always the creek. The life that’s adapted to this type of environment thrives amidst the chaos.


  1. HI Steve...just read yesterdays and today blog..."very interesting" ( everytime I write that Maxwell Smart..(can't remember the ) comes to mind!!
    The drying creek bed and what those creatures can do for survival is something I did not know ..thats cool!!
    We used to chase Crawfish in the brook that flowed through our yard when I was a kid...great fun...and when the brook started to dry up we would turn over rocks and find them there...there was always water pools where the trout would get trapped too..but my Dad had a deep well in the brook bed and we would net the fish and put them in it!!
    The car in traffic illustration is perfect to discribe the every changing creek bed....thanks for passing on your knowledge!!

  2. Hi Steve, I always learn so much from your blog, not just the information you provide, but how to observe things through new eyes! Again, a fascinating post to read through and ponder. ~karen

  3. grammie g - So you were a Get Smart fan? I never got to watch much TV during the 60's. For some reason, never my fault, I always seemed to be in some kind of trouble and TV privledges were always the first thing to go.

    Thanks, Karen.