Modified drought propagation under a changing environment: A case study in the Dongting Lake basin, China

Study region: Four sub-basins of the Dongting Lake basin (DLB), China. Study focus: The "pre-post-disturbance" method was employed to assess the impact of environmental variation on propagation from meteorological drought (MD) to hydrological drought (HD) in the DLB. The study period was split into two sub-periods (i.e, the baseline and impacted periods) via breakpoints of annual runoff series. Additionally, we calculated the drought propagation characteristics in different periods using the run theory. Furthermore, based on copula function and conditional probability analysis, the transmission threshold of MD triggering HD was determined. New hydrological insights for the region: (i) Compared with the baseline period, the severity of HD in the Li River (LR) and Yuan River (YR) increased by 0.5 % and 1.3 % during the impacted period, respectively, while that in the Zi River (ZR) and Xiang River (XR) decreased by -25.9 % and -31.6 %, respectively; (ii) Human activities have weakened the correlation between HD and MD, resulting in various patterns of propagation time in different sub-basins and seasons; (iii) As a whole, propagation threshold from MD to HD became larger during the impacted period, with an average change rate from 0.9 % to 195.5 %.