Multifractal analysis of vegetation regulation on ecohydrological processes in a small watershed

EEMD, detrended fluctuation analysis (DFA), and MF-DCCA analyses were applied to runoff, precipitation, and vegetation cover data in the Quxi River watershed, China. EEMD revealed that high-frequency modes of precipitation and runoff, with a ∼2-week cycle, explained significant data variance. DFA showed precipitation as a random process, while runoff exhibited long-term persistence. MF-DCCA confirmed multifractal characteristics in precipitation-runoff coupling, with the multifractal parameter quantifying hydrological responses. Correlation coefficients between the multifractal parameter and fractional vegetation cover (FVC) were -0.07 (spring), 0.54 (summer), 0.34 (autumn), and 0.42 (winter), indicating vegetation's moderating effect, especially in summer. Although both spring and summer have substantial precipitation exceeding 1,100 mm, the effects of vegetation dynamics on the watershed's water retention capacity differ significantly between the two seasons. This is attributed to the vegetation type characteristics of the small watershed. This novel approach, integrating remote sensing and multifractal analysis, quantified vegetation's regulation of watershed hydrology, offering a robust method to assess water retention capacity. It supports ecological restoration, forest management, and sustainable development in small watersheds, adaptable to regions with large hydraulic projects, enhancing ecosystem stability and biodiversity.