The flood fright has always remained a cause of concern for the planners of various water-based projects. Now, the planners can architect their structures with greater precision to counter the flood threats. The National Institute of Hydrology (NIH), Roorkee, has developed a package called "FLPACK' to estimate the flood for large, medium and small sized catchments by putting in use hydrograph approach and reservoir and channel-routing procedures. The package provides online help for using various options and sub-options to estimate flood. "For the flood estimation for large catchments, the package utilises networking approach, in which flood of individual catchment is calculated and routed through individual channel or reservoir to get final flood hydrograph of the catchments,' says Rakesh Kumar, head of the surface water hydrology at the NIH. "Flood estimation has always remained a challenging component of the water resource project planning. The in-practice unit hydrograph theory for flood estimation can calculate flood for small catchments with reasonable accuracy. However, for the areas having area over 5,000 sq km, the principle of unit hydrograph cannot be applied and therefore the need for developing new technique was felt," he adds. The FLPACK software deals with various options of flood estimation for catchments of different sizes, besides dealing with processing and analysis of rainfall and runoff data. The choice for calibration of unit hydrograph parameters of various sub-catchments and for calibration of routing parameters for different river reaches from historical records are provided in the package that helps in accurate estimation of flood. "The estimation of flood for small or large catchments is pre-requisite for the success of any water resource project. Overestimation of flood could result in construction of uneconomical structures while underestimation of floods could lead to failure of project. The reasonable accurate estimation of floods by using the methodology and software developed by NIH would certainly be helpful in designing and the construction of economically as technically feasible structures,' he asserts.