1998年 6月上旬至 8月下旬 ,大兴安岭地区、内蒙东部连降暴雨 ,全市平均降雨量达 2 2 5 mm,高出历史同期平均值的 5倍 ,最高降雨量达 5 37mm,由于大面积、高强度、长历时的连续降雨 ,致使我市境内的中小河流相继发生历史性大洪水。其中 ,嫩江右岸支流的雅鲁河、阿伦河、诺敏河 From early June to late August 1998, in the Daxinganling area and eastern Inner Mongolia, heavy rains continued in the eastern part of the country. The average rainfall in the city was 225 mm, five times higher than the historical average over the same period with a maximum rainfall of 377 mm. Due to the large area, High-intensity, long-lasting continuous rainfall, resulting in the city’s small rivers have occurred in the historic flood. Among them, the tributaries of the Nen River right bank Yarlung, Arun, Nomin River