This study formulates a new method for flood mapping, while remote sensing technology and flood modelling methods areirrelevant due to unavailability of data. Bad weather and temporal resolution (Revisit time) affect the availability of satellite imagery in peak flood hour and for flood modelling, discharge data are required. Mapping the flood is very important for future references and planning. In Kerala, a major flood occurred was on 1924, which is almost 100 years back and we cannot predict the future events also so that a flood map is essential for the future references. By taking Meloor Panchayat, Kerala as study area we have designed a methodology for calculating the flood inundated area using GIS and PGIS technologies. Flood depth was surveyed using a participatory GIS approach and this paper demonstrates the capability of GIS technology to accurately map the flood inundated area. By this method, we found that the flood height of some regions was up to 7.6 M, which is more than a double storied building and 53% of the study area was flood inundated.