基于条件分布模型的干旱传递概率分析

Analysis of Meteorological and Hydrological Drought Transfer Based on Conditional Distribution Model

气象干旱发展到一定程度可以传递为水文干旱。以潘家口水库流域1961—2010年逐月平均降水数据和潘家口水库的入库径流序列为基础数据,分别计算了1、3、6、12个月时间尺度的标准化降水指数(SPI)和标准化径流指数(SRI),以表征研究区域的气象干旱和水文干旱。基于条件分布模型,分析了不同时间尺度的气象干旱传递到未来的不同等级和不同的预测期(或滞后期)的水文干旱的概率。结果表明,当SPI时间尺度较短或预测期(滞后期)较短时,其对应的SRI水文干旱等级越倾向于维持与SPI相同的干旱等级;随着SPI时间尺度的增长或预测期(滞后期)延长,其对应的SRI水文干旱等级略低于气象干旱或恢复到正常状态。

Meteorological drought can be converted to hydrological drought to a certain extent.Based on the monthly average precipitation data of Panjiakou Reservoir Basin from 1961 to 2010 and the inflow runoff series of Panjiakou Reservoir,this paper calculated the standardized precipitation index(SPI)and standardized runoff index(SRI)at the time scales of 1,3,6 and 12 months to characterize the meteorological drought and hydrological drought in the study area.Based on the conditional distribution model,the probability of meteorological drought in different time scales and different prediction periods(or lag periods)passing to different levels of hydrological drought in the future were analyzed.The results show that when the SPI time scale was small or the prediction period(lag period)was short,the drought level of the converted SRI was more inclined to maintain the same drought level as that of SPI.With the increase of SPI time scale or the extension of prediction period(lag period),the drought level of the converted SRI was slightly lower than that of meteorological drought or returned to normal state.