城市化与城市水环境

选取北京市观象台1941—2013年共73 a的逐分钟降雨量资料，以60 min和120 min两个历时一年一遇的降雨量作为临界阈值，提取降水场次样本，采用Pilgrim & Cordery法推求北京市短历时设计暴雨雨型。各历时的雨型样本选样分别采用自然降雨过程(方法一)和最大历时过程(方法二)。结果表明:两种方法的60 min和120 min雨型分布形状一致，均为单峰型，雨峰位置靠前；但在降雨量分配比例上，两种方法存在差异，自然降雨过程的60 min和120 min雨型雨峰所在时刻降雨量占总雨量的比例比最大历时过程的分别高3.79%和5.83%。

Impact of urbanization on flooding: the Thirusoolam sub watershed: A case study

Choosing the 73 years of by-minute rainfall data from 1941 to 2013 at Beijing Meteorology Observation, we extract the rain samples of 60 min and 120 min, and select the appropriate matches for using Pilgrim &Cordery method to compute the Beijing short lasting design storm pattern. Two schemes can be employed to analyze the design storm pattern: One of rainfall samples are taken from the natural rainfall events, another intercepts the maximum rainfall by minutes. The results show that rainfall patterns of 60 min and 120 min by the two schemes have the same shape, i.e., both have single peak pattern and the peak position is near the front. But two schemes result in different rainfall distribution proportion. Accounted for the total rainfall peak proportion of rainfall patterns of the 60 min and 120 min, the natural rainfall processis 3.79% and 5.83% higher than the maximum lasting process, respectively.