Meander

(Note some observations may be difficult or impossible to make due to high river levels.  I made my observations on a day when the Milford gage level was 6.5 feet.  You can check the river height at http://waterdata.usgs.gov/usa/nwis/uv?site_no=03245500  )

River Hydrodynamics

A meander is basically any bend in the flow of a river.  This word should be familiar to any geocacher who has wander around an are seeking a container!  Where you are standing is in between bends in the Little Miami Scenic River.  The two most interesting things of note are the two opposite river banks to the south and east of where you are standing.  (If the river level is down - like the day I went - you can get a better view closer to the river.)  This earthcache will explain how those two banks got to be this the way they are.

The meander is formed by two forces that are constantly at work on a watercourse, erosion and sedimentation.  One theory is that the meander starts when there is any obstacle to cause for the river to not flow in the straight line.  Once the river or stream has a bend in it the meander process is started.  The characteristics of the 2 banks you see is caused by the complex water flow as it makes the turn around the bend. Essentially, as you see below in the illustration the water making the turn corkscrews about the axis of the center of the river channel.

The simplest way to explain it is the water on the surface is slung to the outside of the turn like a race car making a turn.  The water on the outside of the turn is slightly higher than the inside of the bend - much like an inclined turn on the race track.  This higher column of water developing an unbalanced gradient that moves water back across the bottom from the outside to the inside. You can see that in the upper right hand diagram.  On this diagram on the left the water on the surface are the black lines and the water below the surface are shown as the grey lines.

The diagram below shows what the water velocity looks like in a cross section of the river.  Basically, the highest velocity is in the center of the channel and slower at the air and soil boundaries.  From Section B-B below you can see that the high speed flow to slung toward the outside of the turn.

Meander Formation

Now we'll discuss what the water flow does to the shoreline of the river.  The helical (corkscrew) flow sweeps dense eroded material towards the inside of the bend (location 5).  The inside of the bend is called a point bar. This also leaves the outside of the bend (location 4 above) unprotected - accelerating the erosion and sediment disposition.  What results is a highly eroded outside of the bend and a "beach" of sediment on the inside.  This "beach" is large enough to show up on a satellite photo of the location.

In this picture you are standing at the green arrow.

Logging requirements: To log this earthcache answer the following questions.

1) From the water level to the flood plain level - how high is the dirt embankment on the outside of the bend?

2) What park structure is on the most danger of being affected by erosion?  Where you are now, the canoe access loop ( N 39.11589, W 84.40036), or the path in between  and why?

3) Take an elevation reading at river shore at the earth cache site and the canoe access waypoint.  How far does the river drop between these two points?

4) Is the highest velocity water closer to the inside or the outside of the river bend?

5) Does the water flow in straight lines parallel to the curved river banks?

Optional: A picture of yourself or gps at the overlook.