流域空间结构演化主要受航道等级、城市居中性以及腹地大小的影响。

Basin spatial structure evolution is affected by factors of rank of riverway, geometric centrality of cities, and size of hinterland.

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通过反复调整各因子的等级分界值（经典域和节域），可以使流域产流计算等级和实际等级的拟合率达到最大，其结果比较好。

Continuously readjusting the grade limit value(classical domain and joint domain) of every factor can maximize the ratio of historical runoff to actual runoff production in a drainage basin.

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为了使区域洪涝研究更为具体和可比，本文在分析区域洪涝指标的基础上．提出了流域性洪涝的概念，并以《中国近五百年旱涝分布图集》为基础，建立了淮河流域500年流域性洪涝指标序列及其等级。

It is for the practice and comparison of regional flood research that the idea of Basin-Wide Flood(BWF)is further proposed. Moreover, the index and grades of BWF for last 500-year period in Hua…

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