1450—1949年川渝地区干旱时空变化

以县级行政单元 (县、县级市或区) 为研究单元，定量化川渝地区1450—1949年干旱等级，统计干旱发生年数，利用Matlab 8.3小波分析工具和ArcGIS 10.2 空间分析工具，探索干旱时间和空间变化特征。结果表明：① 500 a中有312 a为干旱年，每1.6 a发生1次，占比62.4%；早期（1450—1650年）干旱发生频率较高，中期（1650—1870年）降低，后期（1870—1949年）明显增高，存在200 a、100 a、65 a、30 a、10 a的周期；② 212个区县干旱等级以大旱为主，一般干旱次之，特大旱最少，其比例分别为50.1%、44.2%和5.7%；③ 空间上以局部干旱为主，范围为1~20个县的年份占了80.4%，其中低于5个县的年份约占56.0%；干旱频次自西向东显著增高，存在明显集聚效应，川西高原和川西南山地旱情较轻，沱江中游、嘉陵江中下游和长江沿岸等地较为严重；85%以上干旱集中于四川盆地；④ 干旱受太阳活动、地理位置、地形地貌、气候变化和土壤性质等自然因素控制，也受到历史时期人口分布和人类生产活动等人为条件影响。

Spatial-temporal Variation of Drought in Sichuan and Chongqing From 1450 to 1949

To explore the characteristics of spatial and temporal variation of drought in Sichuan and Chongqing during 1450 to 1949, employed the wavelet tools of Matlab (Version 8.3) and ArcGIS (Version 10.2) software to analyze the counter data of drought . The results showed that: 1) Drought occurred in 312 years during 1450-1949 A.D, while accounting for 62.4%, once every 1.6 years. The frequency of drought was relatively high in the early period (1450-1650), decreased in the middle period (1650-1870), and increased significantly in the later period (1870-1949), with a cycle of 200, 100, 65, 30 and 10 years. 2) Severer drought was the most common, followed by general drought, and extreme drought was the least, accounting for 50.1%, 44.2% and 5.7%, respectively in 212 statistical units. 3) Spatially, drought was mainly localized, with 80.38% in 1-20 counties, and 56.01% in less than 5 counties. The frequency of drought increased significantly from west to east with obviously agglomeration effect. The drought was relatively light in the western Sichuan Plateau and the southwest Sichuan Mountains region, and severer in the middle reaches of Tuojiang River, the middle and lower reaches of the Jialing River and the both sides of the Yangtze River. More than 85% of the drought was concentrated in Sichuan Basin. 4) Natural factors such as solar activity, geographical location, landform, climate change and soil properties are the main causes of disasters, while human conditions such as population distribution, human production activities and the detailed records are also influencing factors. This result can provide reference for the study of historical climate and the prediction of environmental change in Southwest China.