近550年中国东部旱涝格局时空演变规律及未来预估

Spatiotemporal evolution of drought-flood patterns in Eastern China over past 550 years and future projections

摘要

【目的】我国东部地区旱涝变率大、灾害风险高,但基于长时间历史数据的东部旱涝格局变化规律尚不清晰。为揭示中国东部地区长期旱涝格局的演变规律及其未来变化趋势,【方法】基于我国1470—2020年的长序列气象数据,重构旱涝分布级数,结合小波分析和功率谱分析,识别旱涝变化的主导周期与阶段特征,并使用长短时记忆网络模型预测了东部地区2030—2100年旱涝演变趋势。【结果】结果显示:1470—2020年间中国东部经历了两个偏旱期和一个偏涝期,旱涝情势具有平均20年、50年和180年的变化周期,“北涝南旱”与“北旱南涝”的气候格局以平均200年为周期交替。空间分析显示,近50年来华北、东北西南部等地旱涝波动性高,年际方差阈值较大,气候系统不稳定;而南方大部波动性较低,旱涝变化较为平稳。机器学习预测结果表明,21世纪中叶后东部气候格局将由偏旱向偏涝转变,“北涝南旱”事件自20世纪末期发生频率逐渐增高,并在2036年左右出现阶段性高发,随后频率逐渐下降。而“北旱南涝”事件在此后逐渐增强,并在21世纪中叶达到阶段性高发,之后逐渐减少。【结论】结果表明:中国东部旱涝情势和南北旱涝格局存在长期周期性和阶段性交替规律,未来气候系统可能呈现由偏旱向偏涝的转折趋势。结果深化了对中国东部旱涝时空演变机制的理解,可为水资源优化配置、洪旱灾害风险评估及防御体系构建提供科学支撑,对保障区域水安全具有重要意义。

Abstract

[Objective] The eastern region of China exhibits high drought-flood variability and faces significant disaster risks.However, the evolution of drought-flood patterns based on long-term historical data remains unclear. The aim is to reveal the long-term evolution and future trends of drought-flood patterns in eastern China. [Methods] Based on long-term meteorological data from 1470 to 2020 in China, a drought-flood level series was reconstructed. Wavelet analysis and power spectrum analysis were applied to identify the dominant cycles and stage characteristics, and a long short-term memory( LSTM) model was employed to predict the drought-flood evolution trends in eastern China from 2030 to 2100. [Results] The result showed that between 1470 and 2020, eastern China experienced two predominantly dry periods and one predominantly wet period. The drought-flood conditions exhibited variation cycles averaging 20, 50, and 180 years. The “wet north-dry south” and “dry northwet south” climate patterns alternated with an average cycle of 200 years. Spatial analysis showed that over the past 50 years,regions such as North China and the southwestern part of Northeast China have high drought-flood variability, with large interannual variance thresholds, indicating an unstable climate system. In contrast, most southern regions exhibited low variability and more stable drought-flood variations. Machine learning prediction result indicated that after the mid-21st century,the climate pattern of eastern China would shift from predominantly dry to predominantly wet. Since the late 20th century, the frequency of “wet north-dry south” events had gradually increased, reaching a phase of high occurrence around 2036, followed by a gradual decline. In contrast, “dry north-wet south” events were expected to gradually intensify afterward, reaching a phase of high occurrence in the mid-21st century before gradually decreasing. [Conclusion] The result indicate that drought-flood conditions and north-south drought-flood patterns in eastern China exhibit long-term periodicity and alternating phases. In the future, the climate system may show a transitional trend from predominantly dry to predominantly wet conditions. These findings deepen the understanding of the spatiotemporal evolution mechanisms of drought and flood in eastern China and provide scientific support for optimizing water resource allocation, assessing drought and flood disaster risks, and constructing defense systems.This is of great significance for ensuring regional water security.

关键词

旱涝变化 / 南北旱涝 / 小波分析 / 长时间尺度 / LSTM模型

Key words

drought-flood variation / north-south drought-flood patterns / wavelet analysis / long time scale / LSTM model

基金资助

国家自然科学基金重点项目(42430504)

中央高校基本科研业务费专项资金资助(2243300004)

创新引智基地(111 计划) “流域水安全与综合管理创新基地”(B18006)