淮河流域近500年洪旱事件演变特征分析

Characteristics of flood and drought events of the last half millennium in Huaihe River basin

为了认识淮河流域过去500年洪旱事件发生规律并鉴别当前的洪旱情势，收集并对比分析了流域实测降雨资料、重建历史雨季降雨资料、历史旱涝等级资料、历史洪旱文献记录和历史调查洪水资料等多源洪旱灾害数据。以重建历史雨季降雨资料和历史旱涝等级资料为主要依据，通过滑动平均、频率计算、小波分析和突变检验等方法，分析流域过去500年洪水干旱时空分布特征和演变规律。结果表明，17世纪淮河流域洪旱灾害最严重，但20世纪极端洪旱事件发生频次最多。淮河流域洪旱事件存在40年左右的稳定长周期，主周期从18世纪的15～20年逐渐减少到19世纪的5年周期，近20年来出现2～3年的主周期，洪旱灾害事件呈增加趋势，流域社会经济发展面临着严峻的洪旱灾害威胁。

This study identifies characteristics of flood and drought occurrence of the last half millennium and their evolution to the past years in the Huaihe River basin based on various sources of data recording historical flood and drought events and disasters, including observed rainfall data, reconstructed wet season rainfall data, historical flood/ drought index, history documentary record of floods and droughts, and history flood survey. The reconstructed wet season rainfall and historical flood/drought index are primarily applied to investigate spatial and temporal characteristics of flood/drought events of the last half millennium using the methods of smoothing average, frequency analysis, wavelet analysis and Mann-Kendall tests. Results indicate that over the past half millennium period, flood and drought events were most severe in the 17th century, but occurrence of extreme flood/drought events was most frequent in the 20th century. It is found there was a relatively stable periodic variation of about 40 years over the past half millennium, and the periodic term had been shortened, from 15--20 years before the 18th century to 5 years in the 19th century, and even 2--3 years in recent 20 years. This increasing tendency indicates that the floods and droughts would severely threaten the economic and social development in the study basin.