Simulations of cobble structure on a gravel streambed

We present a two-dimensional, time independent, kinematic simulation of a g ravel streambed that models impacts between clasts as elastic collisions wi thout momentum transfer between discrete, circular disks. The prototype bed forms that we seek to simulate are the "stone cells" observed in Harris Cr eek, south central British Columbia. The basic algorithm causes simulated s tones to cluster into longitudinal structures that resemble such gravel bed forms as imbricate clusters and cluster bed forms. A modified algorithm in corporating programming rules such as stone rotation, entrainment probabili ty inversely proportional to stone size, and the shielding effects of neigh bors causes simulated stones to cluster into structures that resemble trans verse ribs. Trials incorporating the rotation rule, with or without additio nal rules, produce a cobble structure most similar to the prototype. Of all the parameters in the simulation, the number of stones seems to have the m ost control on the development of an extended surface structure.