Tracking hurricane-generated storm surge with washover fan stratigraphy

We use the stratigraphy preserved in a washover fan to reconstruct the timing or emplacement and environmental conditions along the Matagorda Peninsula, Texas, during Hurricane Ike in 2008. Washover fan stratigraphy preserves a topset-foreset break (TFB) that rises 0.42 m in elevation as the fan built landward. We constrain overwash flow depths to 0.1-0.32 m through deposit sedimentology, and tie the rising trajectory of the TFB to rising storm surge water levels measured in the back-barrier bay (0.03 m h(-1)) as the hurricane approached the coast. This relation allows us to estimate that the fan took 0.52-0.90 days to build, and was finished building before the storm surge peaked. This is 15-25% of the 3.5 days of hurricane-induced storm surge near the site. We show how washover stratigraphy can be used to constrain the timing and amount of sediment redistribution on a coast associated with a hurricane; information that is necessary to test and/or calibrate existing numerical models that predict shoreline change during hurricanes.