基于模拟土壤含水量的长江上游#br# 干旱事件时空特征分析

干旱灾害是对我国农业生产和生态环境影响最为严重的自然灾害之一，研究干旱的时空变化特征对干旱的评估、预测有重要的指导意义。研究基于VIC（Variable Infiltration Capacity）模型模拟的50km分辨率的逐日土壤含水量数据，计算土壤含水量距平指数（SMAPI）并分析了长江流域上游1953~2013年历史干旱事件的时空变化特征。结果表明：（1）VIC模型能较好的模拟出1980~2000年长江流域上游出口宜昌断面的流量过程；（2）SMAPI指数能够反映长江流域上游实际干旱的发生、发展过程和严重程度，能够较好地再现历史干旱情形；（3）通过研究长江流域上游的干旱历时 面积 强度关系发现，干旱历时一定时，随着干旱面积的增加，干旱强度总体呈增强的趋势。研究结果对于深入认识长江流域上游历史干旱长期演变特征和增强区域防旱抗旱能力具有一定的理论和实用价值。 关键词： VIC模型；土壤含水量距平指数；时空特征；长江上游

Spatio-Temporal Analysis of Drought Events in the Upper Reaches of Yangtze River Basin Based on Simulation of Soil Moisture

Drought is a disruptive natural hazard that profoundly impacts agriculture and ecosystems,it is important to investigate and assess spatio-temporal characteristics of drought events.Based on the daily soil moisture datasets with a spatial resolution of 50 km × 50 km simulated by the Variable Infiltration Capacity(VIC) land surface macroscale hydrology model,the soil moisture anomaly percentage index (SMAPI) was calculated and used to reconstruct historical drought events and investigation of drought spatio-temporal characteristics between 1953 and 2013 in the upper reaches of the Yangtze River basin.Some important results are as follows:(1) Monthly discharge variable processes at Yichang section simulated by the VIC model were relatively consistent with observed processes during 1980-2000,the results showed that the VIC model built in the study area was feasible and could be used to simulate soil moisture.In addition to good performance in reconstructing historical drought events in the upper reaches of the Yangtze River,SMAPI can also describe drought occurrence,development and severity of large-scale droughts in time and space.SMAPI has clear physical meanings and the drought events identified by SMAPI can be used to analyze the spatio-temporal characteristics of historical drought events.(2) A total of 12 regional drought events were identified in the upper reaches of the Yangtze River basin over the past 61 years,the first ranking severe drought event was from March 4,1969 to July 5,1969(124days) and areal extent was 51.3％.On average,the drought duration,areal extent and drought intensity were 90 days(about 3 months),48.8％ and-11.1％ respectively in the upper reaches of the Yangtze River basin from 1953 to 2013.(3) The relationship between drought area and drought intensity for different drought durations were analyzed.The results showed that drought intensity strengthen as drought area increases for the same drought duration.The research results can provide some theoretical values for the comprehensively understanding spatialtemporal features of historical drought events and a valuable reference for regional drought prevention and resistance in the upper reaches of the Yangtze River basin.