Constraining Big Hurricanes: Remotely sensing Galveston Islands' changing coastal landscape from days to millennia

Climate change models forecast increased storm intensity, which will drive coastal erosion as sea-level rise accelerates with global warming. Over the last five years the largest hurricanes ever recorded in the Pacific (Patricia) and the Atlantic (Irma) occurred as well as the devastation of Harvey. The preceding decade was marked with Super Storm Sandy, Katrina and Ike. A century prior, the deadliest natural disaster in North America occurred as a category 4 hurricane known as `The 1900 Storm' hit Galveston Island. This research aims to contextualize the impact of storms long before infrastructure and historical/scientific accounts documented erosion. Unlike the majority of barrier islands in the US, Galveston built seaward over the Holocene. As the beach prograded it preserved a history of storms and shoreline change over millennia to the present-day. These systems (called prograded barriers) were first studied over 50 years ago using topographic profiles, sediment cores and radiocarbon dating. This research revisits some of these benchmark study sites to augment existing data utilizing state-of-the-art Light Detection and Ranging (LiDAR), Ground Penetrating Radar (GPR), and Optically Stimulated Luminescence (OSL) techniques. In 2016 GPR and OSL data were collected from Galveston Island, with the aim to combine GPR, OSL and LiDAR (GOaL) to extract a high-resolution geologic record spanning 6,000 years. The resulting millennia-scale coastal evolution can be used to contextualize the impact of historic hurricanes over the past century (`The 1900 Storm'), decade (Ike in 2008) and year (now with Harvey). Preliminary results reveal a recent change in shoreline behaviour, and data from Harvey are currently being accessed within the perspective of these initial findings. This dataset will be discussed with respect to the other two benchmark prograded barriers studied in North America: Nayarit Barrier (Mexico) that Hurricane Patricia passed directly over in 2013 and Kiawah Barrier (South Carolina), which was ultimately spared from Hurricane Irma 2017.