Dream Table - Subsidence - Group 1

The above sketch is a mock-up of the way we can show subsidence on our stream table we are developing. We want to have some sort of poles with a wider surface on the end. These will hold up a rubber membrane which the sediment is on. The poles can be adjusted so that they can move up and down. A simple way would be if the poles were screws and they were attached to a board farther down. This would give us the ability to simply screw up or down the poles. We would want the bottom of the box accessible so we could do so. I am sure there is a way to make the poles move vertically with some motor as well. We still need to decide how many sections/poles of the stream table we would want to be able to move.

Dream Stream Table - Group 1

As our stream table is doing fairly well and now we mostly have to wait and see what happens next we have began to develop our future stream table. Some things we want to develop/incorporate into the table are as follows:

-Box

-Sediment supply

-Water supply

-Wave/Tide generator

-Base-level control

-Camera mount

-Uplift/subsidence mechanism

-Gradient control

Continuation of Setup 3 - GROUP 1

(pictures to come soon)

2/25 

Results: With our new sediment input we created splays formed and the channel as filled. We dredged the channel and fixed our sediment input so there would be less sediment feeding into the system. We really need to remove some of the large pebbles which on this scale act as large boulders. The small stream simply cant carry them and can not erode further where they are. We removed a few boulders very carefully as to not harm the system.

2/27

We have ran the system without any changes with our current set up and it seems to be doing very well. It is very very slowly meandering and the meander is even moving downstream! Real rivers take a long time to meander and change course and the same is try for out stream. This is where patience needs to come into our experiment. 

3/1

The nozzel of the sediment feed has fallen off sometime while no one was present which allowed all the sediment to dump into the sream at once. The channel is filled again with sediment. It seems like channel is trying to make a comeback so we will try to leave it run without any input of new sediment (this way the stream can erode and carry the excess sediment in the channels). 

3/2

The stream was not able to make as good of a comeback from our catastrophe the day before as we hoped. We are dredging it once again to get rid of the sand that filled the channel. We didn't change anything else and we began the water again. Right away the stream began to make sand bars and thalwags once again.

Overall the stream table is doing quite well.  It is slowly meandering down the stream toward the basin. There are steam like features forming as well, like the thalwags, sand bars, splays, etc. 

 

Stream Table – 3.4 – Group 2

We did not have to start over on the stream table!  We dredged the white sand that had dumped on the table out of the stream, and removed it from the table.  The stream appears to have continued to meander, and has found its way to the cut banks again.

The black spot in at the head of the table is the plastic

 bottom of the table.  It is also where the water is 

being dribbled on the table.

The white sand is what is being deposited. 
The cut banks are brown/rocky cuts in the white sand.

A new sediment shaker has been designed, and is being implemented in this version.  The last sediment shaker had good concepts, but it was not consistent in its deposition of sediment, we would often walk in to observe it and no sediment would be coming out of the pinch point.  The new sediment shaker uses the angle of repose to control the amount of sediment being fed into the stream instead of a pinch point.

The red cup holds the sand and has a straight, stiff tube 

epoxied to the bottom.  The silver thing strapped on to the cup 

via the black band is a motor with a spinning fan at the 

bottom to shake the cup. There are springs on the three 

posts that also allow the cup to shake.

The delta has migrated channels over the last day:

Yesterday:

In this picture the main channel is flowing toward the 

bottom-right-hand corner of the photo (north-west).

 Today:

In this picture the main channel is flowing toward the
top-right-hand corner of the photo (south-west).

Catastrophic Stream Failure! – Group2

The stopper/pinch-point at the end of the sediment feed shaker slipped off, and allowed the contents of the shaker to pore out onto the table.

Pictures below (taken 11:20 3/1/2011):

This may mean that we may have to re-level the table and start over.

One good thing is the migration of the delta at the end of our stream:

Stream Table 3.3 – Group 2

Stream has cleared its self out.  The sediment shaker has been modified, a pen has been taped to the feeder tube to straighten it (to help avoid clogs), and the pinch on the tube has been lowered to the end of the feeder tube.  The sediment shaker was on this morning (2/28/2011), but was not flowing, so I (Sara) tapped the end of the feeder tube a few times, and it started slowly flowing again.

Pictures of the altered sediment shaker:

Pictures of the meander on the stream table:

Stream Table 3.3 – Sediment Shutoff Again – Group 2

Stream table sediment feed was accidently turned back on this morning, creating many splays (or at least highlighting them) and a small alluvial fan.  At 10:20am both group leaders made an executive decision to turn off the sediment feed, increase the stream velocity to encourage the stream to clear its self out, and dredged the channel to remove the alluvial fan.

 

Stream before dredging:

Stream after dredging: