Peak Flow Estimation by the GRADEX Method: 10 Step-by-Step Applications Bonus: a powerful and easy-to-use software for implementation of method

This book is devoted to the GRADEX method (GRAdient of EXtreme values), developed in the late 1960s by the research group of Electricite De France (Guillot and Duband, 1967). It is a semi-empirical hydrological method, widely used worldwide for estimating rare to very rare flood discharges (return periods greater than one hundred years), especially when a long series of annual maximum daily rainfall and a shorter series of discharges (typically about ten years) are available.The book begins by presenting the theoretical concepts, the underlying assumptions, and the constraints of application of the method. It then proposes ten complete application exercises, solved step by step in strict accordance with the standard approach: (i) fitting a Gumbel distribution to annual maximum daily rainfall; (ii) fitting a Gumbel distribution to annual maximum daily mean discharges, after conversion to runoff depth; (iii) GRADEX extrapolation beyond the ten-year pivot point; and (iv) computing peak flows through an average peak coefficient.