A 1% flood is commonly referred to as a 100-year flood and a 0.2% flood is commonly referred to as a 500-year flood. However, this does not mean there will only be one flood of that magnitude in that time frame. The 0.2% chance identifies that area that has a 0.2% chance of flooding each year. The 1% chance identifies the areas that have a 1% chance of flooding each year. Both of these are shown on the Riley County GIS website (see answer for mapping). The 1993 flood closely reflected the 0.2% chance flood modeling on the FEMA floodplain maps.