A couple of years ago i developed a sampling model for excel that simulated pebble and cobblestone movement in a stream cross-section of depth, width and reach(slope), with cobbles being generated with normally distributed sphericity and size around a mean. The stream bed is modeled as a circular section and pebbles are displayed as(but not modeled as) spheres.
The way stream bed flow modelling is done is to establish a transect across the bed, perpendicular to the flow over a time operiod. One researcher then reaches into the stream and picks up cobbles and measures the long, medium and short lengths of the cobble while the other records from shore. This is done for 100 samples, more or less evenly distributed along the transect. Clearly, there will be a range bias, but the distribution can give a window into the tractive force of the stream. Regression analysis can be done from the dataset to predict movements of smaller or larger sediments.
You'll need Excel 97 or greater with activeX enabled for the live controls. You can enter the three input values manually as well on the "Tractive Force" worksheet. Cobbles are generated on the "Cobbles" worksheet with three linear values, Long, Intermediate and Short using the Box-Muller method to normally distribute the initial random values.
Here's the FILE
...its 2.8Mb.
Lots of tweaks...enjoy
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