NOAA/WDS Paleoclimatology - Isdale et al. 1998 Burdekin River Annual Runoff Reconstruction

Massive, long-lived corals in inshore waters of the Great Barrier Reef contain yellow-green fluorescent bands. These bands are due to terrestrial humic and fulvic compounds incorporated into the coral skeleton during high river flow events. Fluorescence measurements are presented for two colonies of Porites spp. from locations in the path of the Burdekin River floodwaters the major river in north Queensland draining into the Coral Sea. The records extend from AD 1737 to 1980 and 1644 to 1986, respectively. The two independent coral records show a high degree of similarity. The two series are combined and used to reconstruct Burdekin River runoff for the period AD 1644 to 1980. The regression model accounts for 83% of the annual (water year) variability of Burdekin River flow and is verified over independent data. The 337-year reconstruction thus increases by threefold the length of record for considering interannual to decadal climate variations in northeast Australia. Instrumental and reconstructed Burdekin River runoff are closely related to an index of summer monsoon rainfall in Queensland. Thus, the reconstruction provides insights into the behaviour over the past three centuries of both a major tropical river system and the highly variable summer monsoon rainfall in northeast Australia. The reconstructed series shows wetter conditions (higher runoff) in the late-seventeenth to mid-eighteenth centuries and in the late-nineteenth century. Drier conditions (lower runoff) are reconstructed in the late-eighteenth to mid-nineteenth centuries and in the mid-twentieth century.

大堡礁近岸海域的大型长寿珊瑚体内存在黄绿色荧光条带。此类条带的成因是：强径流事件期间，陆地腐殖质与富里酸化合物被纳入珊瑚骨骼结构中。本研究测定了两处滨珊瑚属（Porites spp.）珊瑚群体的荧光特征，采样点位均处于伯德金河（Burdekin River）洪水影响范围之内——伯德金河是昆士兰州北部注入珊瑚海的主要河流。两处珊瑚记录的时间跨度分别为公元1737年至1980年，以及公元1644年至1986年。两份独立的珊瑚记录展现出高度相似的变化趋势。研究将两组序列合并，用于重建公元1644年至1980年期间的伯德金河径流量。该回归模型可解释伯德金河年（水文年）径流量变异的83%，并通过独立数据集完成了模型验证。由此，这份长达337年的重建序列将澳大利亚东北部年际至年代际气候变化研究的可用记录长度增至原有的三倍（即较原记录拓展了两倍）。实测与重建的伯德金河径流量均与昆士兰州夏季季风降雨指数显著相关。因此，本次重建为探究过去三个世纪以来这一大型热带河流系统，以及澳大利亚东北部高度多变的夏季季风降雨的变化特征提供了关键认知。重建序列显示：17世纪末至18世纪中期、19世纪晚期存在降水偏多（径流量更高）的气候时段；而18世纪晚期至19世纪中期、20世纪中期则为降水偏少（径流量更低）的气候时段。