Reproducibility of debris-flow fan physical modeling experiments

Debris-flow fans are common in steep mountainous terrain. The complexity of these environments makes it difficult to be onsite at the time of the debris flow, which has led many researchers to turn to physical models. While physical models have played an integral role in unraveling how alluvial fans have been developed, little work has been done to test and validate the approaches and results reported in physical models. Here, we replicated a debris-flow physical model developed at Utrecht University in a laboratory at East Carolina University (ECU). The ECU physical modeling experiment was done in an independent laboratory from the original study and was conducted with different equipment and different operators. Sediment size and water volume varied slightly from the original experiments. Fifty-six debris flows were released to form the ECU fan. Each debris flow was recorded with video. Terrestrial laser scanning recorded the topographic changes on the ECU fan throughout the experiment. Despite sediment size and water volume differences, ECU’s physical model replicated the autogenic processes promoting flow avulsion patterns in a debris-flow fan with simulated unlimited accommodation space (the trap door in feeder channel and table edge did confine the maximum extent the fan could grow). These results corroborate previous findings from the Utrecht fan and support the repeatability of processes from the different models despite differences in the materials used as the debris-flow medium. Reproducibility also permits future collaborative efforts to run multiple concurrent physical modeling experiments to increase the sample size of the study populations on debris-flow processes and resulting forms.