生活用雨水集流系统设计计算方法初探

Calculation Method of Rainwater Catchment System for Life Purposes

生活用雨水集流系统设计计算的任务,就是确定最佳的集流场面积和贮水窖容积,即满足生活供水需求的集流场面积和贮水窖容积的最小值.定义以最大降雨期初日为初日,以次年最大降雨期初日的前一天为终日的时期为计算周期年,取与频率为P=75%的水平年相应的特征水文年为基本计算年份.根据逐日降水资料,统计出有效降雨(日降水量≥5mm)的降雨期及其降水量和间雨期及其持续日数,确定最大降雨期及其降雨量和最大间雨期及其日数.人均日需水指标与最大间雨期日数的乘积即为最佳贮水窖容积.以最大间雨期为界,将全年最大降雨期和最大间雨期之外的时期分为第一时期和第二时期.根据降雨期及其降水量和间雨期及其持续日数,以不同的方法分别计算第一时期、第二时期和最大降雨期对应的集流场面积,并分3种情况确定最佳集流场面积.

The tasks of the calculation design of rainwater catchment system for life purposes are determining the first rate area of rainwater catching field and the first rate volume of water celler,which are the minimum area of rainwater catching field and the minimum volume of water celler which can meet the needs of supplying life with water.The calculating period year is defined as the period which begins with the first day of maximum rainfall period,and ends with the preceeding days of the maximum rainfall period of next year. We take the characteristic hydrologic year with its frequency of 75% as the basic calculating year.According to the precipitation data day by day,the precipitations of effective rainfall(daily precipitation≥5mm) periods and the days of non-rainfall periods are calculated, and the maximum rainfall period and its precipitation and the maximum nonrainfall period and its days are determined.The first rate volume of water celler is the product of the index of per capita water need and the days of the maximum nonrainfall pereiod.Taking the maximum nonrainfall period as boundary,a year except the maximum rainfall period and the muximum non-rainfall period may be divided into two periods. According to the precipitations of rainfalls and the days of nonrainfall periods, the areas of rainwater catching fields in the first period, the second period and the maximum rainfall period can be calculated by defferent methods,and the first rate area of rainwater catching field can be determined in three conditions.