基于标准水资源指数(SWRI)的流域水文干旱评估——以海河北系为例

Hydrological drought assessment in the river basin based on Standard Water Resources Index(SWRI):a case study on the Northern Haihe River

构建了一个新的水文干旱评估指标——标准水资源指数(SWRI),结合分布式水循环模型、Copula函数及统计检验等方法,形成了一套完整的水文干旱识别、评估及特征分析的基本框架。以海河北系为例,定量识别了1956—2009年间的水文干旱事件,并对其干旱特征及变化规律进行了剖析。结果表明:海河北系近54年发生的34次水文干旱主要集中在短历时、低强度、小面积区间内,空间上主要分布在张家口、大同及北京等地区;干旱指标的联动关系上,干旱历时、强度与面积指标间呈显著的线性或指数相关关系,90%的水文干旱历时低于40个月、干旱面积占比不超过43%,干旱强度低于9.0;在给定的干旱特征指标值(如干旱面积)条件下,另一干旱指标值越大(如强度越大)干旱发生概率越小,且存在明显的特征区间;单变量水文干旱重现期介于联合重现期和同现重现期之间。

In this study, a new hydrological drought assessment index named Standard Water Resources In- dex （SWRI） was established. Based on the SWRI, and a basic framework of hydrological drought identifica- tion, assessment and characteristic analysis was developed by combining the distributed hydrological model, Copula functions and statistical test methods. Taking the Northern Haihe River as a case, the hydrological drought events between 1956 and 2009 were identified quantitatively, and the hydrological drought character- istics as well as the changing rules were analyzed. The results show that 34 hydrological drought events dur- ing the past 54 years all happened within small areas and lasted for a short time period with low intensity. Spatially, they eoncentrated mainly in Zhangjiakou City, Datong City and Beijing Municipality in the Northern Haihe River Basin. In terms of the drought index relationship, there is a strong linear or exponential relationship between the drought duration, intensity and area index. About 90% of the hydrological droughts feature a drought duration less than 40 months, drought area proportion less than 43%, and drought intensi- ty under 9.0. Under the condition of a given characteristic index （such as drought area）, the greater the other drought index （e.g., the drought intensity） is, the smaller the probability of drought occurrence will be, and there exist obvious characteristics ranges. In addition, the single variable hydrological drought re- turn period is between the joint return period and the concurring return period.