【摘要】 为研究过去千年尺度径流变化及其对气候变化的响应,以长江中游鄱阳湖流域为研究区,运用气候模式CCSM4和ECHAM5模拟过去1000 a气候数据,空间降尺度后驱动水文模型模拟了鄱阳湖流域过去近千年流域径流序列.利用快速傅里叶变换、小波分析等手段,分析流域极端径流变化特征、周期和该流域旱涝事件发生频率.结果表明:2种气候模式均能反映出中世纪暖期及小冰期阶段的干湿交替变化,且小冰期内中干旱状态维持时间较长;径流的丰枯变化与降水量变化具有较好的对应关系.CCSM4和ECHAM5模式下发生旱涝灾害与极大极小降水事件发生频率基本相同,径流丰枯变化与降水变化周期相近,均具有30 a左右的主周期,10~15、7 a左右的子周期.小波系数模平方图中30 a左右显著的能量信号揭示了该周期与北太平洋气候的主要环流机制的太平洋年代际振荡周期相近,因此,大气环流涛动是造成气候-水文变化的主要原因.研究结果拓展了基于近代60 a观测记录的流域水文变化的认识,探讨了千年时间长度下流域干湿变化特征和水文对气候响应的动力机制,有助于全面系统认识长江中游在全球气候暖化背景下旱涝极端水文事件的发生机制与变化规律.更多还原

【Abstract】 We took Poyang Basin as a study area to explore runoff variances during the past 1000 years and the response to climate changes. First,we generated meteorological data for the past 1000 years using climate models CCSM4 and ECHAM5. Then the hydrological model of Poyang Basin was driven using the downscaled meteorological data to produce runoff series. We analysed the characteristics of extreme dry and wet events,the periodic change and the frequency of droughts and floods with fast Fourier transformation and wavelet analysis. It is concluded that both climate models are capable to reflect climate changes during Middle Warm Period and Little Ice Age,indicating a longer dry period in Little Ice Age. There is a good relationship between simulated runoff and precipitation,showing that the drought and flood events have a similar frequency with the minimum and maximum values in precipitation. Also,they have the similar primary period of about 30 years and sub-cycle of around 10 to 15 years and 7 years. The significant signal of 30 years in wavelet power spectrum contours illustrates that such period is consistent with Pacific Decadal Oscillation,which is the main circulation mechanism of the North Pacific climate. Hence,atmospheric circulation oscillation may be the main reason causing meteorological and hydrological changes. This paper extends the current studies on hydrological variances based on data records for the recent 60 years,to a time scale of thousand years. Under the background of global warming,this study helpsbetter understand the mechanism and change patterns of drought and flood events in the middle reaches of Yangtze River.更多还原