基于超阈值峰量法(Peaks Over Threshold,POT)抽样,以武江流域犁市站1956—2010年日径流量观测数据资料为基础,对主观和客观多种阈值确定方法进行对比分析,确定合理阈值,建立了流域超阈值洪水样本,分析了流域超阈值洪峰流量、洪量、洪...基于超阈值峰量法(Peaks Over Threshold,POT)抽样,以武江流域犁市站1956—2010年日径流量观测数据资料为基础,对主观和客观多种阈值确定方法进行对比分析,确定合理阈值,建立了流域超阈值洪水样本,分析了流域超阈值洪峰流量、洪量、洪水历时等不同水文变量的变化趋势。结果表明:武江流域近55 a洪水年均发生次数总体呈下降趋势,1970—1980年洪水发生次数偏少,但20世纪90年代后超阈值洪水发生频率明显增加,年均1.35次;洪峰流量值呈现增长趋势,1991—2010年场次洪峰均比1956—1990年增加了520 m^(3)/s,超阈值洪水历时对应下的洪量呈现增加趋势,洪水集中程度加大;1991—2010年样本序列推求的不同重现期的设计洪峰值明显大于1956—1990年样本序列设计值。由此可见,20世纪90年代以后武江流域洪水发生频率增加,洪峰流量和洪量不断加大,洪水集中程度及洪水风险加剧。展开更多
Using the data obtained from sample plots of Phyllostachys pubescens, the dynamic model of energy flow of Phyllostachys pubescens ecosystem was built in this paper.Based on the model,the analysis of energy flow was co...Using the data obtained from sample plots of Phyllostachys pubescens, the dynamic model of energy flow of Phyllostachys pubescens ecosystem was built in this paper.Based on the model,the analysis of energy flow was combined organically with the methods of economical threshold, the concept of economical threshold of energy flow of Phyllostachys pubescen ecosystem (EET) was put forward,and the effect of compensation and super compensation were discussed furthermore.The results showed that the economical threshold of energy flow of Phyllostachys pubescens ecosystem were: EET leaf =0.3133· x 3,EET branch =0.2440· x 1 (where x 1 and x 3 represent energy of leave and branches respectively) ;the effect of compensation and super compensation existed in Phyllostachys pubescens, and the compensation point and super compensation point of Phyllostachys pubescens were 31.33%,13.61% (expressed in defoliation rate)and 24.40%,11.94% (expressed in branch cut rate)respectively.Therefor,this paper will not only enrich the study of energy ecology in the Phyllostachys pubescens ecosystem,but also provide a scientific basis for the management of Phyllostachys pubescens.展开更多
文摘基于超阈值峰量法(Peaks Over Threshold,POT)抽样,以武江流域犁市站1956—2010年日径流量观测数据资料为基础,对主观和客观多种阈值确定方法进行对比分析,确定合理阈值,建立了流域超阈值洪水样本,分析了流域超阈值洪峰流量、洪量、洪水历时等不同水文变量的变化趋势。结果表明:武江流域近55 a洪水年均发生次数总体呈下降趋势,1970—1980年洪水发生次数偏少,但20世纪90年代后超阈值洪水发生频率明显增加,年均1.35次;洪峰流量值呈现增长趋势,1991—2010年场次洪峰均比1956—1990年增加了520 m^(3)/s,超阈值洪水历时对应下的洪量呈现增加趋势,洪水集中程度加大;1991—2010年样本序列推求的不同重现期的设计洪峰值明显大于1956—1990年样本序列设计值。由此可见,20世纪90年代以后武江流域洪水发生频率增加,洪峰流量和洪量不断加大,洪水集中程度及洪水风险加剧。
文摘Using the data obtained from sample plots of Phyllostachys pubescens, the dynamic model of energy flow of Phyllostachys pubescens ecosystem was built in this paper.Based on the model,the analysis of energy flow was combined organically with the methods of economical threshold, the concept of economical threshold of energy flow of Phyllostachys pubescen ecosystem (EET) was put forward,and the effect of compensation and super compensation were discussed furthermore.The results showed that the economical threshold of energy flow of Phyllostachys pubescens ecosystem were: EET leaf =0.3133· x 3,EET branch =0.2440· x 1 (where x 1 and x 3 represent energy of leave and branches respectively) ;the effect of compensation and super compensation existed in Phyllostachys pubescens, and the compensation point and super compensation point of Phyllostachys pubescens were 31.33%,13.61% (expressed in defoliation rate)and 24.40%,11.94% (expressed in branch cut rate)respectively.Therefor,this paper will not only enrich the study of energy ecology in the Phyllostachys pubescens ecosystem,but also provide a scientific basis for the management of Phyllostachys pubescens.
