Reservoir operations play a pivotal role in modifying drought propagation processes, particularly by influencing the transition from meteorological to hydrological drought. This study investigates the drought propagation characteristics in the middle reaches of the Hanjiang River Basin, China, under both natural and observed (reservoir-influenced) conditions. The Standardized Precipitation Evapotranspiration Index and Standardized Streamflow Index were utilized to characterize meteorological and hydrological drought, respectively. The Soil and Water Assessment Tool was employed to reconstruct natural streamflow, providing a baseline for comparison. A nonlinear copula function was applied to model the dependence between meteorological and hydrological drought characteristics, and a Copula-Bayesian network was developed to quantify propagation probabilities. Under the regulation of the Danjiangkou Reservoir, drought propagation characteristics for 1–12-month timescales have shifted markedly: the average propagation time downstream was prolonged from 0.25–0.70 months to 0.94–2.36 months, while the propagation rate declined from 0.83–0.89 to 0.48–0.65, and the sensitivity decreased from 0.83–0.96 to 0.68–0.79. In the natural scenario, the optimal propagation model was based on the Gumbel copula, whereas the observed scenario was best fitted by the Frank copula. The likelihood of hydrological drought increased with the intensity and duration of meteorological drought. However, compared to natural conditions, reservoir regulation significantly delayed the onset and reduced the probability of hydrological drought occurrence. These findings elucidate the nonlinear dynamics of drought propagation and underscore the regulating effect of large-scale reservoirs on downstream hydrological responses.

Sustainable and resilient pavement infrastructure is critical for current economic and environmental challenges. In the past 10 years, the pavement infrastructure strongly supports the rapid development of the global social economy. New theories, new methods, new technologies and new materials related to pavement engineering are emerging. Deterioration of pavement infrastructure is a typical multi-physics problem. Because of actual coupled behaviors of traffic and environmental conditions, predictions of pavement service life become more and more complicated and require a deep knowledge of pavement material analysis. In order to summarize the current and determine the future research of pavement engineering, Journal of Traffic and Transportation Engineering (English Edition) has launched a review paper on the topic of “New innovations in pavement materials and engineering: A review on pavement engineering research 2021”. Based on the joint-effort of 43 scholars from 24 well-known universities in highway engineering, this review paper systematically analyzes the research status and future development direction of 5 major fields of pavement engineering in the world. The content includes asphalt binder performance and modeling, mixture performance and modeling of pavement materials, multi-scale mechanics, green and sustainable pavement, and intelligent pavement. Overall, this review paper is able to provide references and insights for researchers and engineers in the field of pavement engineering.