Characterization of Drought Propagation in the Han River Basin Based on Chaos Theory and Nonlinear Dynamic System

Abstract

This study characterized drought propagation in the Han River basin based on chaos theory and nonlinear dynamic systems. The nonlinear complexity of drought propagation, specifically between meteorological and hydrological droughts, was identified using convergent cross-mapping and phase-space reconstruction techniques. The analysis results on the causality of drought propagation between meteorological and hydrological droughts revealed that among the 24 middle-sized watersheds of the Han River basin, 11 watersheds had bidirectional causality, and the other 13 watersheds had one-directional causality. This study also confirmed that there were large correlations between the two drought types when 12 of the 13 watersheds with one-directional causality had a lag time of 4 months and the remaining watershed had a delay time of 7 months. The complexity of the interaction between different droughts was confirmed through adjustments of key parameters, such as the embedding dimension, time delay, correlation dimension, and Lyapunov exponent. The approach proposed in this study made it possible to analyze the nonlinear dynamic characteristics of drought propagation, which have not been analyzed in previous studies.