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长江流域继 1998年发生全流域性大洪水后 ,1999年发生了较大洪水。通过洪水及汛情对比 ,1998年与1999年长江洪水的共同点是洪水位均较高 ,但性质不同 ,1998年是全流域性大洪水 ,1999年则属区域性较大洪水。 1998年宜昌出现 8次洪峰 ,最大 30d洪量与 1954年相当 ,1999年宜昌仅出现 3次洪峰 ,最大只有 5760 0m3 /s,较 1999年小 ,最大 30d洪量亦较 1998年小 2 58亿m3 ,反映了 1999年长江上游来水量不大。从长时段的洪量对比来看 ,1999年洪水是较集中的一次洪水 ,而 1998年则是历时长的洪水。分析认为 ,由于两年洪水的差异及 1998年汛后堤防工程的结果 ,使两年洪水间的溃口水量、溃垸数、淹没耕地及工程险情都有较大差别。反映了 1998年洪水后防洪工程建设发挥重要作用
After a major flood in the Yangtze River basin in 1998, a serious flood occurred in 1999. Through the comparison of floods and floods, the commonalities of the floods in the Yangtze River between 1998 and 1999 are that the flood level is higher but of a different nature. In 1998, it was a major flood in the whole basin, and in 1999 it was a regional flood. In 1998, there were 8 flood peaks in Yichang, the maximum flood volume in 30 days was the same as that in 1954. Only 3 flood peaks occurred in Yichang in 1999, the largest being only 5760 0m3 / s, smaller than that in 1999. The maximum 30d flood volume was also smaller than that in 1998 by 25.8 billion m3, It reflects that there was not much water in the upper reaches of the Yangtze River in 1999. In terms of flood volume over a long period of comparison, floods were more concentrated in 1999 than in floods in 1998. The analysis shows that due to the difference of floods in two years and the result of embankment project after flood season in 1998, there is a big difference between the two years of flood water, the number of embankments, the flooded cultivated land and the construction danger. Reflects the flood control project in 1998 to play an important role