Research Of Channel Pattern’s Characteristics Based On Non-equilibrium Thermodynamics And Chaos

In this paper, based on non-equilibrium thermodynamics and chaos, channel pattern of alluvial river is studied from a macro point of view to explore the characteristics of different channel patterns. The main research content is as follows.(1) The discrimination of channel patters is proposed. The concept of coordinating development in the sciences of society and economy or of environment and economy is used in this paper. The discrimination is established by coordinated developmental degrees of different channel patters. The results show that the influence on channel pattern by river boundary conditions is greater than the incoming flow and sediment conditions; the coordinated developmental degree of rivers is proportional to their stability and ordering. Therefore, the proposed method is important for the classification and discrimination of channel patters.(2)Based on non-equilibrium thermodynamics, local entropy production is a function of energy dissipation function, and energy dissipation function can be written as the sum of the product of the generalized forces and the corresponding generalized flux of an irreversible process. In this way, once the generalized forces and the corresponding generalized flux of river are formed, the formula of energy dissipation function of river can be obtained. Energy dissipation rate of river system is obtained.(3)Based on the data of the lower Yellow River during the range of 21 years, the unit stream power and the year information entropy for 6 reaches are analyzed. The results show that the unit stream power and the value of the year information entropy of a river increased as the instability of the river increased.(4)The discriminant of the stability of channel pattern is studied. According to the relationship between energy and entropy production rate, as well as the definition of excess entropy production, excess energy dissipation rate can be obtained by analogy. Based on excess energy dissipation rate of river, the discrimination of channel pattern stability is obtained. According to the discriminant, the stability is analyzed for 6 reaches on the lower Yellow River.(5)The chaos characters of monthly runoff series and monthly sediment concentration for 6 reaches of the lower Yellow River are analyzed. The results show that,when the wandering river changes into the meandering river, the value of the maximum Lyapunov exponent increased along the way of river. At the same time, chaotic attractors of the river system increased with the value of the maximum Lyapunov exponent increased. In this way, the chaotic state changes into senior chaotic state(dissipative structure).