Hurricane Harvey // Sand Peel Sculpture 4

Context, Description, and Interpretation:

Peel 4 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: Above the pre-Harvey deposits and maximum flood erosional surface (red line) is sediment deposited from suspension.  This is eroded by the channel cut erosional surface (green line) and overlain by channel cut deposit which contain dunes as well as thin mud layers indicating varying flow energy.

Peel 4 records pre-Harvey mud deposits at the base of the peel, overlain by the Harvey erosional surface exhibiting a large scour pocket cutting into the mud layer.  Above the erosional surface, a thick package of sand shows no clear sedimentary structures and likely fell out of suspension.  Moving up section there is an erosional surface (green line) that was caused by the channel cut.  Above the erosional surface there is large scale trough cross stratification from dunes, indicating medium flow velocity.  Mud layers throughout the dunes indicate varying flow velocity.  The red arrows indicate easterly flow below the channel cut erosional surface and northerly flow above it.

The west end of Peel 4 and north end of Peel 5 abut at a right angle creating a 3D corner view.

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 to middle adjustment phase

  • August 28-September 15, 2017: The flow energy in Buffalo Bayou was dropping during this time.  A high concentration of sediment in the water caused sediment to be deposited out of suspension. 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 4. Flow was to the north.