To describe flood risk, hydrologist compute flood thresholds (quantiles) that will be exceeded with specified probabilities. This is easier to do should a record of observed floods be available for the site in question. The new statistical methods promoted here combine flood quantile estimates for nearby gauged locations with flood risk estimated based on local physiographic measurements for the catchment. Critical parameters are the distance, and the difference in area, between any gauged catchments and the catchment of concern.