[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 threshold 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.