Bed load transport modeliing.  

New equation using 2D shear stress distributions

  Bed‑load transport in gravel‑bed rivers is often estimated using reach‑averaged shear stress, but this approach misses the wide range of shear stresses created by complex flow fields. We developed a modified, subsurface‑based transport equation that incorporates the full distribution of shear stress within a reach and tested it using bed‑load data from Oak Creek, OR. Two‑dimensional flow modeling showed that shear‑stress distributions had consistent shapes across discharges and could be parameterized with a Gamma function. When flows were high enough to mobilize the pavement layer, the new equation performed similarly to the traditional reach‑average approach. At lower flows, however, it successfully captured transport occurring in small, high‑stress portions of the bed—an improvement over conventional formulations that underestimate sediment movement under these conditions.

NSF Award # 1619700