Flood estimation is now at the time has lot of importance because the world been facing flood problems more frequently than ever. Moreover, while developing a project i.e. dam construction it is an important and basic thing to perform its flood studies especially for the design of spillway and for dam safety. So, this book provides some tools and methods for an accurate flood assessment. It describes estimations of peak flood discharges mainly by using HEC-HMS software and by flood frequency analysis to compare the results.