Following this general introduction, Chapter 2 provides the structure of the program and the description of the parameters involved in the prediction tool. Then, Chapter 3 provides an explanation of the estimation and schematisation of the hydraulic and structure parameters. Finally, Chapter 4 describes the use of NN_OVERTOPPING 2, including: i. a description of the contents and organisation of the input file that must be prepared for NN_OVERTOPPING 2, (see Section 4.3). ii. a description of the contents and organisation of the output file that will be produced by NN_OVERTOPPING 2, (see Section 4.4). iii. and the guidelines to run NN_OVERTOPPING 2, i.e. the procedure that must be followed to obtain the output file of (ii) given an appropriately generated input file in (i), (see Section 4.5).