极端气候事件对洞庭湖水文连通性变化的影响OACSTPCD

The Dongting Lake basin is the region of the middle reaches of the Yangtze River that provides ecosystem regulation functions.The hydrological connectivity of the Dongting Lake basin experienced profound and complex changes as a result of climate change and human activities.China emphasizes that ecohydrological environmental protection should be put in the first place,and assessing the impact of the occurrence of extreme climatic events on the regional hydrological environment would be of great significance in protecting the stability of the regional ecohydrological environment.Previous study quantitatively characterizes and predicts the changes in the hydrological connectivity of Dongting Lake in the last decades.It is beneficial for us to fully understand the water resources evolution of Dongting Lake,to ensure the security of water resources which has a significant theoretical and practical meaning in the Dongting Lake basin. The hydrological connectivity index was applied to characterize the changes in the hydrological connectivity and to study the contribution of extreme climatic events.This study was carried out using the hydrological connectivity index method,ETCCDI extreme climate index,Hurst index,and mathematical and statistical analysis methods. The results showed that the hydrological connectivity index presented the characteristics of summer>autumn>spring>winter.From the remote sensing images extracted from the water body,it could be seen that the Dongting Lake hydrological network was characterized by inhomogeneity.It is found that the hydrological connectivity of Dongting Lake would continue to change excessively in the future according to the persistence prediction.Dongting Lake ⅡC and PC had an obvious response to extreme precipitation events,while Dongting Lake ⅡC and PC did not significantly respond to extreme climate events. These results indicated that the hydrological connectivity of Dongting Lake was relatively stable in the last three decades.Without the interference of human activities,the hydrological connectivity of Dongting Lake would continue the decreasing trend in the future.The hydrological connectivity index gradually increased with the increase of water level and the growth rate gradually slowed down,and the increase of water level had a positive influence on it with a decreasing marginal effect.Extreme precipitation events had a more obvious positive effect on the hydrological connectivity,while extreme temperature events had a smaller effect on the hydrological connectivity.This could be because heavy rainfall events may affect lake and river levels through direct water inputs,whereas extreme high or low temperatures may only indirectly affect lake and river levels through the evapotranspiration of water.