两类阈值法识别的东江流域水文干旱形成与演化过程差异OA北大核心CSTPCDEI

Monthly flow data from the Longchuan and Boluo stations,representing upstream and downstream control sections of the Dongjiang River Basin,as well as monthly inflow and outflow data from the Fengshuba,Xinfengjiang,and Baipenzhu reservoirs within the basin for the period 1956-2010 were used.The reservoir regulation flow reconstruction method was employed,along with the variable drought threshold(VDT)and fixed drought threshold(FDT)methods,to identify hydrological drought events.Furthermore,the study analyzed the disparities in the formation,evolution process,and response to large reservoir regulation between hydrological droughts identified by the two threshold methods.The results reveal that,due to the different target drought background concepts for the VDT and FDT methods,the evolution processes,such as the start,peak intensity,and end months and the distribution within a year of hydrological droughts identified by the two methods are significantly different.Moreover,hydrological droughts identified by the VDT method are evenly distributed in each month of a year,while those identified by the FDT method are concentrated in dry season(from October to March of the following year)in the Dongjiang River Basin.The FDT method typically identifies the peak intensity of hydrological droughts,occurring from December to February of the next year,with the majority of droughts ending in pre-flood season,specifically in March and April.The utilization of the FDT method ensures that the start,peak intensity,and end months of hydrological droughts align well with the dryness/wetness characteristics of the Dongjiang River Basin.Both the VDT and FDT methods are able to characterize the development and recovery patterns of hydrological droughts.The changes in the evolution characteristics of hydrological droughts identified by the two methods and their responses to reservoir regulation are similar.In particular,both methods can reflect the effects of large reservoir regulation in shortening drought duration,reducing drought severity,delaying the start and peak intensity months of hydrological droughts,and advancing the end month of droughts.