Time-scaling Differences between Poyang Lake Inlet and Outlet COD Series: Monofractal and Multifractal Aspects

Three fractal methods are applied to the time-scaling properties analysis of water COD series from Poyang Lake Inlet and Outlet in China. The results show that these COD series are characterized by long-term memory, 1/f noise and multifractal scaling, and these characteristics have obvious difference between the Lake Inlet and Outlet. The comparison results suggest that monofractal and multifractal parameters can be quantitative dynamical indexes reflecting environmental capacity of Poyang Lake. Furthermore, we investigate the frequency-size distribution of COD series from Poyang Lake Inlet and Outlet. Our findings suggest that water COD is an example of a self-organized criticality (SOC) process. Based on concept of self-organized criticality, we analysis the cause that different scale-free power-law behavior between COD series from Poyang Lake Inlet and Outlet. This work can be helpful to improvement of modeling of lake water quality.