Fast water can cause extraordinary bedload transport.Of the record floods considered here,the Jul.26,2022 urban flash flood on the upper River des Peres,St.Louis,Missouri provides par-ticularly well-constrained data on flow conditions associated with large block movement.Field measure-ments and a detailed lidar survey show that concrete slabs as large as 3.0 × 2.5 × 0.33 m3 were moved from the open channel to reside 215 to 450 m inside a 6.5 m-diameter drainage tunnel,some to become part of a 10-m long imbricated pile.Peak flows of 160 m3/s were recorded at a gauging station located only 1.6 km upstream of the tunnel entrance,which provides a good estimate of 4.2 m/s for the peak flow velocity in the tunnel.Available observational data and a new theoretical analysis show that the ra-dius of large boulders that can be moved by flowing water is directly proportional to the velocity head.
NETL
NSTL
万方数据
