It's a good idea to consider an example from a Less Economically Developed Country (LEDC) and compare and contrast this with an example from a More Economically Developed Country (MEDC).
There are several possible case studies which could be selected, such as Holderness in Yorkshire, UK and Thailand's 2004 boxing day flood.
Perhaps think about the causes underlying these events, in terms of the geography of the coastline and possible trigger events such as natural disasters.
In addition, explore the existing or possible defence strategies (soft or hard engineering techniques and reasons as to which method is more favourable) to prevent such floods in future.