Hydrologic Modification and Vanishing Self-Organized Criticality of River Flows Caused by Dam Operations

Abstract

AbstractWidespread dam construction has significantly altered natural hydrologic processes and consequently affected river ecosystems. The concept of self-organized criticality (SOC) implies the ability of a system to create and maintain its own function and has important implications for the entire ecosystem, thus can be used to assess anthropogenic disturbances. This study focuses on how reservoir operations affect the SOC behavior of river flows. Taking five large-sized reservoirs in China as examples, the maximum likelihood methods, Kolmogorov Smirnov testing and Detrended Fluctuation Analysis, are used to examine the typical SOC fingerprints for daily river flow series, including their power law frequency-magnitude distributions and long-range correlations. The results show that with increasing reservoir-modified pressure, the frequency-magnitude relationships of natural flows gradually deviate from heavy-tailed power laws and tend to behave as normal or lognormal distributions, characterized by vani...