This experiment is unchanged from Experiment 4. We are doing a re-run with changes made to improve consistency in the sediment feed system.
Hypothesis
Because we have not changed the variables from Experiment 4, we anticipate similar results. If the sediment feed functions properly, it is likely an alluvial fan will develop because of an over supply of sediment. However, if the sediment feed functions properly, there should not be development of a subsequent incised channel.
Set Up
The parameters of Experiment 5 are identical to those of Experiment 4. The one adjustment is a detachment of the discharge hose from the sediment feed housing. Discharge is now fed by placing the hose directly into the plastic soda bottle located on the sand bed surface. Sand is dropped into the bottle by the feed mechanism, where it mixes with the discharge (Fig. 1).
Observations
1) An alluvial fan developed from the mouth of the soda bottle onto the table, and the original channel was abandoned (Fig. 2a, b).
2) Headward erosion developed from the basin toward the toe of the alluvial fan (2a, c).
Interpretations (Each interpretation is tied by number to an above observation.)
1) As hypothesized, an alluvial fan developed because of a load greater than could be transported by the available discharge.
2) Headward erosion proceeded from the basin toward the alluvial fan, because of the change in position of the entry point for discharge entering the basin.
Hypothesis
Because we have not changed the variables from Experiment 4, we anticipate similar results. If the sediment feed functions properly, it is likely an alluvial fan will develop because of an over supply of sediment. However, if the sediment feed functions properly, there should not be development of a subsequent incised channel.
Set Up
The parameters of Experiment 5 are identical to those of Experiment 4. The one adjustment is a detachment of the discharge hose from the sediment feed housing. Discharge is now fed by placing the hose directly into the plastic soda bottle located on the sand bed surface. Sand is dropped into the bottle by the feed mechanism, where it mixes with the discharge (Fig. 1).
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Figure 1: Discharge and sediment now mix within the plastic soda bottle, rather than within the previous housing.
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Observations
1) An alluvial fan developed from the mouth of the soda bottle onto the table, and the original channel was abandoned (Fig. 2a, b).
2) Headward erosion developed from the basin toward the toe of the alluvial fan (2a, c).
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| Figure 2a: View of entire stream table with alluvial fan at the head and headward erosion at the toe. |
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| Figure 2b: Close up of alluvial fan. |
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| Figure 2c: Close up of headward erosion. |
Interpretations (Each interpretation is tied by number to an above observation.)
2) Headward erosion proceeded from the basin toward the alluvial fan, because of the change in position of the entry point for discharge entering the basin.
Technical Issues
Though the wicking problem was greatly reduced, dampening of sediment caused it to accumulate on the rounded side of the plastic bottle above the level of discharge entry. The sediment would pile until it collapsed into the bottle, causing a discontinuous, fluctuating sediment supply. Occasionally, the pile would rise to the level of the sediment delivery mechanism, resulting in clogging.
Technical Issues
Though the wicking problem was greatly reduced, dampening of sediment caused it to accumulate on the rounded side of the plastic bottle above the level of discharge entry. The sediment would pile until it collapsed into the bottle, causing a discontinuous, fluctuating sediment supply. Occasionally, the pile would rise to the level of the sediment delivery mechanism, resulting in clogging.
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