Stream width distribution dynamics in response to network expansion and contraction (2016)

Undergraduates: Eric Barefoot, George Allen

Faculty Advisor: Tamlin Pavelsky
Department: Geology

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Stream networks can be conceptualized as fractals. That is, small and narrow streams are more abundant than wide rivers. Useful for a wide range of applications including estimating greenhouse gas emissions from rivers, the fractal nature breaks down at the level of very small streams. In particular, the dynamics of small-scale network expansion and contraction with discharge are poorly understood. Here we investigate the relationship between discharge and the distribution of stream widths in a headwater catchment to describe an expanding and contracting stream network, including effects on the water surface area distribution. Using methods developed by Allen et al., (in review), we collected over ten high-resolution surveys of stream width at different streamflow conditions in Stony Creek, a headwater catchment in the Duke Forest. Preliminary results suggest that the distribution of stream width exhibits hysteresis during a storm. As storm waters rise, the distribution varies non-linearly, reflecting a complicated balance between the effects of at-a-point stream expansion and overall network expansion. As the storm waters recede, however, the relationship is linear, suggesting that as the water level falls, the network narrows uniformly, and network contraction has a less pronounced impact. These results advance our understanding of small-scale stream network dynamics during storms, and will help constrain global estimates of dynamic changes in surface water extent.