The Chao Phraya River Basin (CPRB) of Thailand faces flooding almost every year. The
severest flood occurred in the CPRB in 2011 with the highest property damage costs (46.5
billion USD) and the highest casualty (813 deaths). The objectives of this study were thus to
(1) determine flood risk indices and categorize them into four risk zones (low, moderate, high,
and very high) across 994 sub-districts in the CPRB during the six rainy months (May–
October); and (2) propose specific measures for flood risk management for each of the
categorized risk zones. The flood risk indices were assessed as the product of two hazard
variables (flood levels and monthly cumulative precipitation) and the vulnerability variable
(land uses). The findings revealed spatiotemporal variations in flood risk. Spatially, the subdistricts deemed to be in the high or very high flood risk zone were mainly located close to the
Chao Phraya River (CPR), where the flood levels reached 1.1 – 4 m in depth; whereas the subdistricts detected in the low or moderate flood risk zone were located further away from the
CPR. Etc...