摘要
全球气候变化加剧及大规模人类活动影响,水文时间序列一致性假设不再成立,导致基于一致性假设的传统水文频率分析方法得到的设计结果可信度受到质疑。为了研究渭河流域降雨时间序列的非一致性对未来年份内某一重现期设计暴雨的影响,采用时变矩法及时间序列分解合成法对修正后的GCM降雨时间序列进行非一致性频率分析,并预测2050年、2075年、2100年相应的100 a?500 a重现期的年最大24 h设计暴雨。研究发现:(1)修正后的年最大24 h降雨时间序列均值及方差都存在显著的非一致性;(2)时变矩法设计结果较传统频率分析方法有较大差异,比如2100年100 a?500 a重现期的设计暴雨相比于传统方法分别增加29.09%、39.99%; (3)同时考虑均值及方差变异的时间序列分解合成法设计结果与时变矩法相当,但500 a重现期设计暴雨值相比于传统方法增加的程度稍小于时变矩法,其21Q0年100 a?500 a重现期的设计暴雨值较传统方法分别增加26.91 %、19.69%。
Because of global climate change and anthropogenic activities,the assumption that the hydrological time series is stationary will be no longer valid. Thus,the design values calculated with the traditional hydrological frequency analysis method based on the stationarity assumption might be unreliable and thus the nonstationary frequency analysis methods are required. This paper is aimed to study the impacts of the nonstationarity of the annual maximum （AM） 24 h precipitation series of the Weihe River （Weihe） Basin of Shaanxi Province,China on the design values for the given return periods. Both the GCM daily precipitation data series for the time period of 1901-2100,which is obtained by combining the outputs of the 20c3m and sresa1b emission scenarios of model csiro_mk3_5,which are available on the website （http：//www-pcmdi.llnl.gov/）,and the observed daily precipitation data of 20 rainfall gauges within the Weihe River （Weihe） Basin for the time period of 1951-2011 are collected. With these data,two AM series of 24 h precipitation over the whole Weihe River Basin are prepared,one is the 1901-2100 GCM series and the other is the observed 1951-2011 series. Because of the coarse spatial resolution of the GCM output,there exists great uncertainty with the 1901-2100 GCM series which must be rescaled firstly. Based on the theory of statistical downscaling method and the observed AM 24 h precipitation series of 1951-2011,the AM 24 h GCM precipitation series of the 1901-2100 is rescaled by the mean-correction factor and standard deviation-correction factor to reduce the errors in the GCM outputs. With the rescaled AM 24 h GCM precipitation series,two nonstationary frequency analysis methods,i.e. the method of time-varying moment and the decomposition and combination method,are employed to estimate both the 100 a and 500 a design values of the AM 24 h precipitation for the design years of 2050,2075,and 2100,respectively. The results of the two nonstationary frequency analysis methods have significant discrepancy comparing with those of the traditional method which is based on the stationary hypothesis. Three conclusions are made as follows. First,there are nonstationarities in both the mean and variance of the rescaled AM 24 h GCM precipitation series. Second,the results of the time-varying moment method are obviously different from those of the traditional frequency analysis method. For the year of 2100,the AM 24 h precipitation design values obtained by the former method for the return periods of 100 years and 500 years are 29.09% and 39.99% greater than the design values from the latter method,respectively. Third,for the method of decomposition and combination considering both the nonstationary mean and variance,its design value has the similar trend with those of the time-varying moment method for the same return period,but has a relative lower increasing rate than the latter method for the return periods of 500 years. For the year of 2100,the AM 24 h precipitation design values obtained by the former method for the return periods of 100 years and 500 years are 26.91% and 19.69% greater than the design values from the traditional method,respectively.
出处
《干旱区地理》
CSCD
北大核心
2014年第3期468-479,共12页
Arid Land Geography
基金
国家自然科学基金重大项目(51190094)
国家自然科学基金项目(51079098)
关键词
水文频率分析
非一致性
GCM
时变矩法
分解合成法
hydrological frequency analysis
nonstationarity
GCM
the time-varying moment method
thedecomposition and combination method
