More than 2 million hectares of the lower Mekong River ?ood plain (Cambodian Plain), which extends from southern Cambodia to the border with Vietnam, is cultivated with rice; and more than 60 % of the population in the ?ood plain are farmers involved in rice cultivation. Rice production in this area is seriously affected by ?oods almost every year; on the other hand, the farmers need ?oodwater for their crop ?elds. Therefore, the farming in this area is about coping with ?oods, and ?ood countermeasures should be carefully planned based on good understanding of the livelihood of the farmers. Thus, this study aimed to identify ?ood-vulnerable rice-growing communities in the Mekong River ?ood plain in Cambodia. In this research, we proposed a useful methodology to make ?ood inundation maps by conducting a simple analysis by combining satellite-based digital elevation model (DEM) and river water level data based on the ?ood characteristics in this area. Then, rice-crop vulnerability maps were derived from previous maps and results from other past researches using the geographical information system (GIS). Comparison among those maps was also conducted to ?nd out the relationship between DEM and people’s lifestyles in this area. This simple, inexpensive methodology was proven useful to understand major crop damage and vulnerability in relation to ?oods in this area, based on ?ood characteristics in the Cambodian ?ood plain. Because the method is a GIS-based approach, it can deliver more accurate results when provided with more accurate data.