基于水分盈亏指数的四川省小麦生育期干旱风险评估

Drought risk assessment based on crop water deficit index during wheat fertility periods in Sichuan Province

利用四川省135个气象台站1961~2014年逐日气象资料和29个农业气象观测站的小麦观测资料,选取水分盈亏指数作为干旱评估指标,分析了54年来四川小麦7大种植区不同生育期的各级干旱时空变化特征及其风险分布情况。结果表明:小麦各生育期发生干旱站均次数以川西南山地最多,其多年平均值达0.9以上,可谓十年九旱。各区干旱站均次数的时间变化趋势不明显。生育阶段以孕穗-抽穗期发生干旱频率较高,其次是拔节-孕穗期,最低的是抽穗-乳熟期。从干旱频率空间分布特征来看,川西南山地是发生轻旱频率最高的地区,川西高原中旱和重旱的发生频率要高于其它各区,盆地各区域中只有盆中和盆西部分区域发生干旱频率相对较高。小麦干旱风险分布情况为川西南山地以及川西高原的南部区域是干旱高风险区,大部分区域可达极重风险,盆地以盆中为干旱风险高发区。

The temporal-spatial characteristics and risk of droughts for wheat in Sichuan province are analyzed using daily weather data during 54 years from 135 weather stations and wheat observation data from 29 agricultural stations. The crop water deficit index is selected for drought risk assessment for each growing period of wheat. The result shows that drought occurred during the wheat fertility period most frequently at the southwest Sichuan mountain region. That region has more than nine drought occurrences for every ten years. No obvious changing trend is identified on the temporal scale in terms of drought occurrences per station. Drought occurred most frequently at booting and heading stages of wheat,then followed by jointing and booting stages. The heading and milky stages has least drought occurrences. In the view of spatial distribution characteristics,the southwest mountain region of Sichuanhas most light drought occurrences,while the west plateau of Sichuan has the highest medium and severe drought frequency. Two sub-regions within the Sichuan basin have relatively high frequency of drought,including central part of the basin and west part of the basin. The southwest mountain region and southern part of west plateau are high drought risk regions,and most regions can reach extremely drought risk. Central part of basin is also high drought risk region.