A review on Thermodynamics in Water Cycle with Emphasizing on Entropy and Maximum Entropy Production Principle

Hydrological cycle is directed into thermodynamic non-equilibrium state and maximum entropy production through thermodynamic processes. Therefore, it is possible to understand and describe hydrological cycle through computation of entropy production rate and the maximum entropy production principle (MEP). Based on MEP, if there are sufficient degrees of freedom within a system, it will adopt a steady state at which entropy production is maximized under existing restrictions. This principle can help to estimate the hydrological components and parameters without need for detailed understanding of watershed characteristics. Due to the importance of this issue in the science of hydrological modeling and the lack of Persian resources in this field, the present study examines the hydrological cycle from a thermodynamic point of view using valid scientific sources. In this study, the hydrological cycle is considered as a thermodynamic system and the method of calculating entropy production rate by components of water balance is presented. Also, how to estimate hydrological components using the MEP principle is explained in a simple example. Overall, the MEP principle holds great promise for equipping us with a better understanding of the organization of hydrological processes within the Earth system and development of the models based on non-equilibrium thermodynamic.