A framework for assessing propagation thresholds from meteorological to hydrological and agricultural drought under future climate change

Understanding drought propagation dynamics is essential to prevent future drought disasters under the changing climate. However, the complex pathways and critical thresholds governing the propagation between different drought types remain insufficiently understood. This study provides a framework to assess future propagation risks in the Luan River Basin (LRB) in China. Based on multi-model climate projections from CMIP6, a CA-Markov model was employed to predict future land use changes, and a SWAT hydrological model was used to simulate basin-scale hydrological processes from 2015 to 2050. Then, future meteorological, hydrological, and agricultural drought events were identified, and their propagation dynamics were characterized. Copula functions were applied to analyze joint risks and their drivers across different carbon emission scenarios. Results demonstrate that despite projected increases in both temperature and precipitation, enhanced interannual variability alters drought dynamics in the LRB. Drought propagation efficiency is sensitive to emission scenarios, with high-emission pathways exhibiting greater uncertainty, a longer duration, and an increased contribution of the recovery stage to overall drought risk. Furthermore, joint probability analysis indicates that rising emission levels depress the critical thresholds for drought propagation, which is linked to prolonged recovery stages and the accumulating effects of successive meteorological droughts. Therefore, advancing low-carbon development are critical to mitigating the risk of drought propagation. The future drought assessment framework could effectively capture the dynamics of multi-type drought propagation and quantify future risks under changing climate conditions. Results can provide scientific guidance for coordinated drought early warning and adaptive water resource management.