西南地区农业洪涝等级指标构建及时空分布特征

利用西南农业区341个气象站1961—2010年的逐日降水量资料，结合灰色关联分析，以重庆市单站洪涝指标为原型，对该指标降水量临界值进行幅度为-50～+50 mm、步长为1 mm的增减，得到该区域各省份相对应的101个洪涝指标，并结合基于各洪涝指标计算得出的洪涝发生强度与农作物洪涝实际受灾程度的相关性、指标与历史洪涝灾害记录的吻合性以及分省指标的可比性，确定了各省农业洪涝等级指标，同时，分析了该区域农业洪涝灾害的时空分布特征.结果表明： 构建的云南指标为原指标+16 mm，贵州指标为原指标+30 mm，四川-重庆指标为原指标+40 mm，指标定义的洪涝指数与各省份受灾率的相关系数分别为0.314（P<0.05）、0.553（P<0.01）和0.305（P<0.05），指标与历史灾害记录的吻合性较高.1961—2010年，云南、贵州、四川-重庆洪涝发生较严重的年代分别为20世纪80年代、20世纪90年代、20世纪80年代和21世纪初，洪涝多发区分别位于云南西南和东南部、贵州西南部和四川盆地的西部和东北部.

Level indicators construction and temporal-spatial distribution features of agricultural flood in the southwest of China.

Flood level indicators of southwest provinces were built in this study by using daily precipitation data of 341 weather stations in southwest agricultural areas from 1961 to 2010 combined with grey correlation analysis. In the process of building the indicators, we took single station flood indicators of Chongqing as the prototype. Through increasing and decreasing the precipitation thre shold of Chongqing indicators by the amplitude of -50-+50 mm and the step size of 1 mm, each province got 101 groups of flood indicators. Based on the correlation between flood intensity calculated by all the indicators and crop flood real seriousness, coincidence between indicators and historical flood records and the comparability of different province indicators, we finally constructed agricultural flood level indicators of each province step by step. According to the flood indicators, we also analyzed temporal spatial distribution features of flood disaster in southwest agricultural areas. The results were as follows: the final indicators of Yunnan were the original indicators plus 16 mm, while it was plus 30 mm for Guizhou and plus 40 mm for Sichuan Chongqing. The correlation coefficients between flood index defined by indicators and affected ratio were 0.314 (P<0.05), 0.553 (P<0.01) and 0.305 (P<0.05), respectively. The coincidence was relatively high between indicators and historical flood records. The ages in which flood disaster appeared very serious were 1980s in Yunnan, 1990s in Guizhou and 1980s and 2000s in Sichuan Chongqing in the nearly 50 years. In the southwest and southeast of Yunnan, southwest of Guizhou and west and northeast of Sichuan Basin, the flood disaster was prevalent.