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本文论述我国西北地区的自然地理特点,着重分析暴雨强度衰减指数n值的变化规律。通过分析得出:1.n值随温度梯度增大而增大;2.n_1值随海拔高度增高而变小;3.n_2值随各地气温平均日较差增大而增大。进而论证我国西北地区,尤其是山前下垫面易急剧增温的地段,其降雨量远比其他地区为小,但其短时段的暴雨强度却很大的特征。在计算设计暴雨和决定桥梁孔径时,不可忽视这一特点。
This article discusses the natural geographical features of northwestern China, focusing on the analysis of the variation of the n value of the rainfall intensity decay index. The results show that: 1.n value increases with increasing temperature gradient; 2.n_1 value decreases with the increase of altitude; 3.n_2 value increases with the increase of average daily temperature. Furthermore, it proves that the rainfall in northwestern China, especially in the front of the piedmont, is much warmer than that in other regions, but the intensity of heavy rainfall in a short period of time is very big. This feature can not be ignored in the calculation of design torrential rains and the determination of bridge aperture.