Multi-scale entropy analysis of Mississippi River flow

Multi-scale entropy (MSE) analysis was applied to the long-term (131 years) daily flow rates (Q) of the Mississippi River (MR) to investigate possible change in the complexity of the MR system due to human activities since 1940s. Unlike traditional entropy-based method that calculates entropy at only one single scale, the MSE analysis provided entropies over multiple time scales and thus accounts for multi-scale structures embedded in time series. It is found that the sample entropy (S _E) for Q of the MR and its two components, overland flow (OF) and base flow (BF), generally increase as time scale increases. More importantly, it is found that there have been entropy decreases in Q, OF, and BF over large time scales. In other words, the MR may have been losing its complexity since 1940s. We explain that the possible loss in the complexity of the MR system may be due to the major changes in land use and land cover and soil conservation practices in the MR basin since 1940s.