Hurricane Harvey // Sand Peel Sculpture 6

Context, Description, and Interpretation:

 Peel 6 records the initial erosion during the maximum flooding phase, rapid deposition of sands as the energy levels quickly dropped, then a late adjustment as flow changed direction 90 degrees as stranded water cut down through the bar and returned to the original channel.  The hydrologic archive shows the water level’s rapid rise and fall and the return to the channel > 30 days post maximum flooding.  The human impact showed a change from food and shelter needs to financial needs when the bayou returned to the channel.

Summary: At the base of Peel 6 are pre-Harvey mud deposits cut by the Hurricane Harvey maximum flood erosional surface.  This is overlain by a thick package of sediment that dropped out of suspension as energy levels rapidly declined.  The channel cut erosional surface cuts into this unit and is overlain by channel cut deposits.

At base of Peel 6 are pre-Harvey mud deposits truncated by the Hurricane Harvey maximum flood erosional surface (red line).  The sand overlying this erosional surface contains no distinct sedimentary structures, indicating it was likely deposited as suspended sediment that settled out of the water during a period of rapid velocity decrease.  This package is overlain by planar bedding indicating upper flow regime and increase in velocity (lower white dashed lines).  Above this is a channel cut erosional surface (green line) overlain by organic material.  From this erosional surface to the top of the peel is channel cut deposit; sedimentary structures including trough stratification, ripples, and mud layers indicate that it is a waning flow deposit.  The red arrows indicate the change from easterly flow below the channel cut erosional surface to northerly flow above it.

Event Timing

• Flood phase

  • August 28, 2017: The red line marks the erosional surface above the low energy pre-Harvey deposit. This erosion occurred during the flood phase as Buffalo Bayou rose to its peak at about 1:00am on August 28, with a measured gauge height of 15 m (41.9 ft). Flow was to the east.

• Early adjustment phase

  • August 28-30, 2017: The water level dropped rapidly through August 30, with flow conditions were in the upper flow regime. On Peel 6, the sediment deposited during this time is between the red line and the green line. Flow was to the east.

• Late adjustment phase

  • October 1-November 29, 2017: As the water level dropped, stranded water returned to the main channel, eroding across the newly deposited bar at a right angle. These deposits are from the green line to the top of Peel 6. Flow was to the north.