Projections of Future Beach Loss due to Sea Level Rise for Sandy Beaches along Thailand's Coastlines

Coastline recession caused by sea level rise due to climate change has become one of the most significant issues worldwide. Thailand's coastlines is also likely to face erosion, especially in the low-lying areas, and its future projection due to sea level rise is necessary. This study compiled a database of beach characteristics, including grain size diameter, beach slope and beach width, to assess the projections of future beach loss along Thailand's coastlines against sea level rise scenarios of the Coupled Model Intercomparison Project Phase 5 (CMIP5) in 2081-2100, relative to a reference period 1986-2005 by using the Bruun rule. Future national beach loss rates were projected to be 45.8% for RCP2.6, 55.0% for RCP4.5, 56.9% for RCP6.0 and 71.8% for RCP8.5. In addition, the rate against the sea level scenarios projected by each CMIP5 model for RCP4.5 ranges from 49.1% for MPI-ESM-LR to 73.4% for MIROC-ESM-CHEM. Based on the current beach situation, sandy beaches in 8 and 23 out of 51 zones will disappear for RCP2.6 and RCP8.5, respectively. These findings will help governors and stakeholders develop adaptation strategies against beach loss due to sea level rise.