中文摘要：

在全面收集中国西北三省（区）历史洪水、定点洪水、动点洪水调查结果的基础上，分内陆河、黄河、长江流域进行了洪水的面频率分析，得出了西北干旱区局部暴雨洪水面频率曲线，应用条件概率理论将面频率与点频率叠加，处理工程水文设计中的历史洪水和特大洪水。实例应用结果表明：该方法有效地提高了适线精度，更加符合实际且节约工程造价。

英文摘要：

Based on comprehensive survey of historical,fixed point and moving point flood in six provinces of Northwest China,this paper analyzed flood surface frequency on inland rivers,the Yellow River and the Yangtze River,obtained the local storm flood surface frequency curve of three big river basins of the arid areas in Northwest China,and applied superposition method of combining surface frequency and point frequency to deal with historical and unusual floods in hydrological design. The results of case application show that this method effectively improves comfortable line accu-racy and more practical and save the engineering cost.