Characteristics of the spatial-temporal evolution of flood disasters in Heilongjiang province from 1965 to 2014

Based on monthly precipitation data of 63 meteorological stations in Heilongjiang province from 1965-2014, the flood grades (including moderate, mild, and severe floods) were calculated using Z index, regional flood index, the mathematical statistics, inverse distance weight interpolation and other methods.The temporal-spatial evolution characteristic of flood and its change trend were also analyzed in Heilongjiang province.The results show that the number of regional moderate, mild and severe flood disasters occurred in Heilongjiang province are 7, 7 and 6, respectively in recent 50 years.The precipitation climatic trend rate is 0.864 mm/a.The frequency of flood disasters demonstrates an unevenly distribution, with 104 times of moderate flood, 74 times of mild flood and 29 time of severe flood.The areas with the flood disasters happened frequently expand year by year.Meanwhile, the percentage of stations occurring flood disasters to the total stations has a significant difference year by year and shows an escalating trend.The rates of escalating trend of moderate, mild and severe floods are 1.3/10 a, 1.6/10 a and 0.85/10 a, respectively.The highest frequencies of flood disasters occurred in 1980s, 1990s and after 2010.Hegang, Yichun, Heihe and Mudanjiang regions are the main disaster areas, and the Greater Khingan Range and Daqing regions are the next ones.