农业干旱风险评估有助于提升区域灾害风险管理和决策水平，减轻干旱灾害造成的损失。利用历史降水资料、灾情数据和社会经济数据，本文以地级市为评估单元，以各评估单元3 种播种面积最大的农作物为评价对象，在发展和完善现有连续无雨日干旱评估指标的基础上，结合作物不同生长阶段对干旱反应的差异，设计了一套农业作物干旱等级判定及其概率研究方法，同时，提出评估单元不同作物干旱等级损失率的计算方法，构建了农业干旱风险损失评估的计算模型。本文以西南区为案例区进行了农业干旱风险评估，结果发现：①采用研究方法求算的各评估单元风险损失结果能有效地表达各评估单元之间的农业干旱风险差异；②根据计算的农业干旱风险指数划分的风险区能比较准确地反映案例区内农业干旱风险的空间分布规律；③西南区农业干旱高度和重度风险区主要分布在该区西部和北部的一些高原、山地之中，而轻度和中度风险区则主要分布在其东部、中部和南部地区。
Agro-drought risk assessment is helpful for improving ability of regional disaster management and mitigating the drought-induced loss. We used historic precipitation, disaster loss and socio-economical data in China as the basic data. The assessment was performed for the three crops with the biggest sown areas in each of prefecture-level region. By using the consecutive rainless days to scale the drought severity, we developed different standards of indexes to judge drought severities. The standards were relying on seasons, crop types and crop growth stages. Moreover, we developed a model for each type of crops. This model could be used to calculate risk loss under different severities of drought. In the next step, we integrated risk loss of each type of crops to assess the regional drought-induced agricultural loss, by weighting average approach. Using the above method we took Southwest China as a case area to assess its spatial distribution of agro-drought risk. We found that (1) from the results tested by historical loss of agro-drought hazards in recent 10 years (1997-2006) in Southwest China, the risk loss calculated by the model can reveal the loss differences between assessment units; (2) different risk regions divided by the composite risk index can well reflect the differences of spatial distribution in Southwest China; (3) high and extreme risk areas of agro-drought were primarily in the plateaus and mountains in the western and northern parts of the region, and slight and moderate risk levels were observed in the eastern, central and southern parts of Southwest China.
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