Entropy for Hydrological Applications: A Review

The concept of entropy was first introduced in thermodynamics to describe the evolution of all systems towards more disordered states. In the XX Century Shannon used the same concept to introduce a measure of uncertainty referred to a random variable and since then the so-called information entropy has been used in many science fields to describe the amount of information provided by one or more random variables. About 25 years later from its introduction, Shannon's entropy made its first appearance in water resources area, thanks to Amorocha and Espildora. From that moment on, information entropy and Information Theory related concepts have been widely applied in hydraulics and hydrology. Here we present a brief review of the main applications of entropy in water engineering practice, from hydraulic problems to the optimization of hydrological monitoring networks.