Flood is a natural demolishing phenomenon, forecast of which is of high importance, to reduce its impact. On the other hand, it also serves as a major source of water when conserved through proper means. For this purpose, estimation of flood is of at utmost importance. The present study employed regression analysis between weighted maximum rainfall and maximum stream flow for the flood events of respective catchments of Vellar river basin. Regression equation was framed between Annual Maximum Daily Rainfall, Stream Flow and area for each catchment. Based on the equation, flood prioritization rank was given to each of the catchment. Thereby, Lower Vellar is prioritized as first rank and Upper Vellar is prioritized as last rank respectively. This study reveals that the Lower Vellar is the most vulnerable catchment and which needs flood control measures.