My fiancé, Cody, and I went boating on the Wabash River this summer. We put the boat in at New Harmony, IN, motored around for a while, then anchored at a section of sand in the river. We walked around on the sand and picked up shells. After a while, we got back in the boat to do some more riding. This stop on the sand sparked some questions in me.
“ The size of the particles comprising a bar is related to the size of the waves or the strength of the currents moving the material, but the availability of material to be worked by waves and currents is also important.”
(2003). Encyclopedia-Sandbar. NationMaster.com. Retrieved September 20, 2009. From http://www.statemaster.com/encyclopedia/Sandbar
The text book, Applied Aquatic Ecosystem Concepts , discusses this concept well:
“ Flow through meander causes predictable erosion and deposition patterns. Maximum velocity and greatest erosion occurs on the outer side of each bend, creating a deep hole, or thalweg. As water flows around a bend, the water level is raised at the outside of the bend and causes a helical flow of water towards the opposite bank. A back eddy results and deposits sediments eroded from the bed and bank receiving high water velocities. This explains why point bars develop in depositional zones in a downstream direction.”
A website about Peacock Bass features a quotation from Spence Petros that says the following about sandbars, “These ever-changing, dynamic structures are formed by flowing rivers and are revealed during low water conditions.” This implies that during high water conditions, a sandbar might not be visible.
Hollan, T. (2003). Prime Patterns for Peacock Bass. Peacock Bass online. Retrieved September 20, 2009. From http://www.peacockbassonline.com/prime_patterns.html
Yes, after skimming through several websites that talked about various aspects of sand bars, I learned that a great deal of rivers have sand bars. Two very common examples are the Colorado and Missouri Rivers.
I also asked this question to my fiancé and his dad, since they are both avid fishermen of several rivers in the area. They agreed that the majority of rivers do in fact have sandbars.
If I teach in a school near a river, this could be a good assignment for students to use their local funds of knowledge to extend this activity to reach any way that they use a river, even if it is just to look at.
In a classroom, my students could do data collection, and compare different rivers’ statistics.
This activity could also tie in with other types of weathering and erosion.
I could do a lesson in my classroom about how rivers connect different regions and states, much like railroads and interstates. This could be incorporated with a social studies lesson on transportation.