中文摘要：

在干旱事件不确定性和枯期径流变异性的双重影响下，水文干旱特征时序非一致性问题为其联合分布模拟带来困难。基于东江干流测站日径流过程数据，采用游程理论提取水文干旱事件，并结合干旱特征均值变化、时序一致性分析及边缘分布模拟，以确定干旱事件融合及剔除评判标准的合理取值。基于Rosenblatt变换Cramer—vonMises检验统计量拟合方法，构建水文干旱特征两变量联合分布Copula模型，并根据同频法设计两变量组合值。通过对比枯期径流变点分隔子序列干旱特征，分析变化环境下东江流域水文干旱特征及缺水响应。结果表明：水文干旱事件融合和剔除的评判标准值分别取0．1和0．3比较合理。干旱特征两变量之间具有较高的正相关性，但不同时间系列不同变量之间的联合分布及边缘分布最优模型并不一致。流域水库尤其是新丰江水库的径流调节作用，对于缓解东江中下游水文干旱效果明显，超阈联合重现期为2年的设计干旱持续时间、总缺水量和最大日缺水量分别减少了63％-71％、71％-84％和30％-47％，但如果要满足东江河道内最小管理流量目标，其依然分别达到了12-18d、6114万．9030万m3和715．0万-929．0万m3。

英文摘要：

Modeling the joint distribution of hydrological drought associated with non-stationary drought properties under the effects of uncertain drought events and low flow variability is difficult. Daily streamflow data from gauging stations in Dongjiang River basin, South China are used. On the basis of run theory for truncating drought events, al- terations are analyzed in terms of mean values for hydrological drought properties and their non-stationary statistics with changes in pooling and exclusion ratios. Bivariate copula functions are built for modeling the joint distribution of hydro- logical drought according to the test method of Cramer-von Mises statistics associated with Rosenblatt transfer. Further- more, a pair of designed drought values for predefined joint return periods is calculated using the equalized probability method. Changes in drought properties associated with dependence and joint distribution, as well as water shortage un- der a changing environment in Dongjiang River basin, are investigated by comparing two subseries of droughts separa- ted by the change point in low flow. Results demonstrate that the pooling and exclusion ratios set to 0. 1 and 0.3, re- spectively, are rational. Despite positive dependence between drought properties, the bivariate and univariate models for hydrological droughts vary under different time series and variable pairs. The remarkable decrease in drought dura- tion and water shortage in the middle and lower streams is attributed to the regulation of water reservoirs, particularly the Xinfengjiang Reservoir. When the joint return period exceeds the threshold by 2 years, the designed duration peri- ods, total volumes, and daily maximum water shortage levels decrease by 63%-71%, 71% -84%, and 30%- 47%, respectively. However, they still account for 12-18 d, 61.14-90. 30 million, and 7. 150-9. 290 million 3 m , respectively, provided that instream flow satisfies the water demand in Dongjiang River basin.