基于史料的海南岛历史干旱时空分布

Spatiotemporal Distribution of Historical Droughts on Hainan Island Based on Historical Records

摘要: 气候变化背景下，理解热带地区长时段的干旱演变规律对于评估未来风险至关重要。本研究基于《中国气象灾害大典·海南卷》，通过建立标准化的强度等级与结构类型划分体系，分析了海南岛公元805年至2000年的干旱历史。结果表明：1) 在时间上，干旱事件的发生频率呈显著上升趋势。但是由于史料记载完整性的影响，早期(如唐代)的干旱记录可能严重低估。若以“有记录年份中的干旱发生比例”进行估算，仍可观察到干旱频率自明清以来明显增加，并在现代(1949~2000年)达到高峰，年均记录频率为2.04次/年。2) 从干旱强度上看，干旱强度已经从单季节性干旱为主转为现代跨季节连续性干旱为主。其中，连续性干旱(≥2季)转变为“大旱”强度的概率(即在整个时期内，连续性干旱中达到“大旱”强度的事件数占连续性干旱总事件数的比例)为95.2%，远高于单季节干旱转变为“大旱”强度的70.7%。3) 在空间上，东部以单季节干旱(占东部全部干旱事件的44.1%)为主，西部(三季连旱占西部总干旱事件的47.9%)和南部(三季连旱占南部总干旱事件的46.7%)以长期干旱为主，而北部的单季节干旱、两季连旱和三季及以上连旱的发生频率较为均衡(分别占北部总干旱事件的34%、33%和33%)，三种干旱类型的分布比例相对接近。整体形成了以西部沿海为核心的、以长周期结构性干旱为主的重灾区。从文献记录分析，海南的旱灾已从偶发季节性威胁演变为常态化、结构性持续干旱为特征的系统性风险，但早期史料缺失可能会影响结果的客观性。

Abstract: Against the backdrop of climate change, understanding the long-term evolution of drought patterns in tropical regions is crucial for assessing future risks. This study, based on the Encyclopedia of Meteorological Disasters in China: Hainan Volume, analyzes the drought history of Hainan Island from 805 to 2000 AD by establishing a standardized classification system for drought intensity and structural types. The results indicate that: 1) Temporally, the frequency of drought events shows a significant increasing trend. However, due to limitations in the completeness of historical records, early drought documentation (e.g., during the Tang Dynasty) may be substantially underestimated. When estimated based on the “proportion of years with recorded droughts”, a clear increase in drought frequency is still observable from the Ming and Qing dynasties onward, peaking in the modern period (1949~2000) with an average annual recorded frequency of 2.04 events per year. 2) In terms of drought intensity, the dominant pattern has shifted from single-season droughts to modern multi-season continuous droughts. The probability of continuous droughts (lasting ≥2 seasons) intensifying into “severe droughts”—defined as the proportion of continuous drought events that reached severe intensity relative to the total number of continuous droughts over the entire period—is 95.2%, significantly higher than the 70.7% probability for single-season droughts. 3) Spatially, the eastern region is primarily characterized by single-season droughts (accounting for 44.1% of all drought events in the east), while the western (47.9% as three-season droughts) and southern (46.7% as three-season droughts) regions are dominated by prolonged droughts. The northern region shows a relatively balanced distribution among single-season droughts, two-season consecutive droughts, and droughts lasting three or more seasons (34%, 33%, and 33%, respectively), with the three types occurring in comparable proportions. Overall, a high-risk zone centered on the western coast has formed, characterized by long-term structural droughts. Analysis of historical records suggests that drought disasters in Hainan have evolved from occasional seasonal threats into systemic risks marked by normalized, structurally persistent droughts. However, the absence of early historical materials may affect the objectivity of the findings.