TABLE OF CONTENTS 

results and discussion

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INTRODUCTION


APPROACH


MINI-EXAMPLES
1-D CLOSED BASIN

2-D DROP IN A BUCKET

 

RESULTS & DISCUSSION

 

CONCLUSIONS

 

REFERENCES

 The model seems to run things close to what they should be.  However, there are some apparent issues with the model.  In the river problem, shear stresses and viscosity were not included, yet the wave was not maintaining its shape.  The changing of the wave's shape should only happen if there is some external force acting on the wave.

I was also having stability issues with the model.  There may be an issue in the code, rather than the time step because as I decreased the time step to times that should promote stability, the program ran the same way.  There must be some other issue in the code as evidenced by the problem in the 1-D river example. 

Below is a chart of the gage height at the dam.  The blue line is the actual data from the USGS website, and the red line is the model output. 

There were 2 model runs as shown by the break in the red line.  The first run became unstable and this is known because the depth was oscillating back and forth and the oscillations were growing rather than decaying.  The second run did not follow the blue line when the blue line spiked.  I may be bold, but I don't believe it is so much a problem with the model, but a problem with the data.

I tried to explain the spike in the actual data of the gage at the dam.  So I reviewed the input data.  The graphs below are the flow at the same time period of Pheasant Branch and the Yahara River and the flow at the dam.  Pheasant Branch has very low flow compared to the other rivers.  Also, 6-Mile is comparable to Pheasant Branch, so I am not really considering those two rivers.  Looking at the Yahara chart, the flow is around 100 m3/min and decreasing to even negative values.  The outflow at the dam is around 275 m3/min and increases to about 325 m3/min.  What this tells me is that there is more outflow at this time than inflow so the water level should be decreasing.  Then I thought maybe it was rain, so I checked the precipitation data at this time.  However, there was no rain at this time also.  Thus, I cannot really explain the spike in the actual data.