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较之气候水文平均态的缓慢变化,特大洪水引发的灾害对人类社会影响更加显著,而关注极端洪水、认识小概率事件需要更长时间序列。本文通过对太湖钻孔的沉积和磁学参数特征研究,对比太湖文物发掘的历史洪水资料,试图多指标定量重建太湖长序列极端洪水。太湖水则碑对1600～1954A.D.特大洪水记录了15次,通过与现代洪水仪器记录对比和论证,其最低4.03m水位相当于1921～2004A.D.观测太湖的年最高水位80%百分位。太湖钻孔中的沉积粒度和磁化率特征捕捉了水则碑洪水序列中的85%的洪水年,同时补充了水则碑洪水漏失的信号。3次能够被历史文献佐证的洪水沉积信号发生在1766A.D.、1875A.D.和1882A.D.,其洪水水位估计在4.0～4.1m,4.1～4.2m和4.13～4.23m。频谱分析显示了沉积洪水指标与水则碑洪水指标具有3个同步的重现期,分别约在90～102年、60～62年和42～44年。分析历史洪水与PDO一致性的统计关系,获得估计概率为0.17～0.20,肯定了太湖洪水年与PDO存在关联,反映出历史洪水的发生与现代过程相同,受到了太平洋季风环流和夏季降水控制。这些结论为延长洪水时间系列、分析小概率事件、认识极端洪水特征和重现期等提供了重要水文依据。
Compared with the slow change of the climate hydrological mean, the catastrophic impact caused by catastrophic floods has a more significant impact on human society. However, focusing on extreme floods and recognizing small probability events requires a longer time series. Based on the study of sedimentation and magnetic parameters of Taihu Lake borehole, this paper compares historical flood data of Taihu artifacts excavation and attempts to quantitatively reconstruct long-series extreme flood in Taihu Lake by multi-index. Taihu water monument on the 1600 ~ 1954A.D. extraordinary flood record of 15 times, compared with the modern flood record and demonstration instruments, the minimum 4.03m water level is equivalent to 1921 ~ 2004A.D observed the annual maximum water level in Taihu Lake 80% Divide. Sediment particle size and magnetic susceptibility features in the Taihu Lake borehole captured 85% of the flood year in the Shui Meitong flood series, while supplementing the flood loss signal from the water monument. Three flood-sedimentary signals that can be corroborated by historical documents occurred at 1766A.D., 1875A.D. And 1882A.D. and their flood levels were estimated at 4.0-4.1m, 4.1-4.2m and 4.13-4.23m. Spectral analysis shows that there are three synchronized recurrences of the sediment flood indicator and the water monument flood index, which are about 90-102 years, 60-62 years and 42-44 years respectively. The statistical relationship between history flood and PDO consistency is analyzed. The estimated probability is 0.17 ~ 0.20. It is affirmed that there is a correlation between the flood years in Taihu Lake and PDO, reflecting that the historical floods are the same as the modern ones and controlled by the Pacific monsoon circulation and summer precipitation. These conclusions provide an important hydrological basis for extending the flood time series, analyzing small probability events, understanding extreme flood characteristics and recurrence periods.