基于遥感的华北区域性农业干旱事件识别及特征分析

IDENTIFICATION AND CHARACTERISTICS ANALYSIS OF REGIONAL AGRICULTURAL DROUGHT EVENTS IN NORTH CHINA BASED ON REMOTE SENSING

关键词:  农业干旱事件  时空连通性  CWSI  华北地区  时空特征

Key words:  agricultural drought events  spatial-temporal connectivity  crop water stress index (CWSI)  North China region  spatial-temporal characteristic

摘要:

目的 气候变暖背景下，全球范围内干旱灾害频率进一步加剧，中国是世界上干旱灾害最严重的国家之一，严重威胁农业生产和粮食安全。方法 文章基于MODIS数据计算作物缺水指数（Crop Water Stress Index，CWSI）表征农业干旱，考虑时空连通性，对2001—2020年华北地区区域性农业干旱事件进行三维识别，提取事件的历时、影响范围、强度、烈度以及空间重心5个特征变量来分析其时空演替特征。结果 （1）2001—2020年华北共发生35场区域性农业干旱事件，历时不超过5个月的事件占80%，且随着历时增加事件的影响范围明显增加，40%的事件影响了全区90%以上的耕地；干旱历时是影响干旱综合特征烈度的更主要因素。（2）20年间事件发生频率有所增加，但事件的历时、影响范围、强度以及烈度均有所下降，每年的3—6月和9—11月为区域性农业干旱事件的频发时段，且春旱强度整体高于秋旱；（3）区域性农业干旱事件更频繁地发生于华北中部和西北部，且空间重心在20年间存在东移趋势。结论 研究结果系统展示了华北地区区域性农业干旱事件的发生特征，可为区域农业生产、干旱风险管理以及防灾减灾决策提供科学支撑。

Abstract:

In the context of climate warming, drought disasters have become more frequent around the world. As one of the world's most drought-affected countries, China's agricultural production and food security are threatened. Based on MODIS data, crop water stress index (CWSI) was used to characterize agricultural drought. And, considering spatial and temporal connectivity, identification of agricultural drought events in North China from 2001 to 2020 with three-dimensional spatial and temporal components, and five characteristic variables: duration, impact range, intensity, severity, and spatial center of gravity were extracted to analyze their temporal and spatial continuity characteristics. The results were categorized into the following three points. (1) During 2001—2020, there were 35 regional agricultural drought events in North China, 80% of which were less than 5 months. Moreover, the impact range increased significantly as duration went on; 40% of events affected over 90% of arable land; Duration was the most dominant factor influencing the combined characteristics of drought, which were referred to as intensity. (2) Duration the last 20 years, events had increased in frequency; however, their duration, impact range, intensity and severity had declined, each year March-June and September to November were the most frequent periods of regional agricultural drought. Intensity of spring drought was higher than that of autumn drought. (3) During 20 years, regional agricultural drought events occurred more frequently in central and northwestern North China. The center of gravity tended to move east. In summary, these results systematically demonstrate the characteristics of regional agricultural drought events occurring in North China, which can provide scientific support for regional agricultural production, drought risk management, and disaster prevention and mitigation decisions.