| To reach the four big planning control targets about sponge city construction policy:rainfall runoff volume capture,runoff pollution control,runoff peakflow control,rainwater resource utilization,based on the operating characteristics of roof rainwater utilization system the study of the optimization scheme of rainwater storage facilities detention volume was carried out in this article.The meaning of volumetric runoff coefficient was analyzed in this paper from the point of view of statistical methods and applicable scope.The cities typical roof types such as waterproof brick,asphalt linoleum are chosen as the research object to analyze the influence factors of roof rainfall runoff coefficient by monitoring actual rainfall and it found that rainfall depth has the biggest impact on volumetric runoff coefficient and then it put forward the roof even volumetric runoff coefficient method and was verified.The distribution and correlation of different pollutions were studied in this paper though monitoring the roof rainwater quality during the rainfall process and the roof rainwater pollution characteristics were analyzed.The rainwater quality control volume in first flush was determined and the goal of runoff pollution control was achieved by understanding the variation law of roof rainwater pollution concentration and determining the first flush effect: it takes 5 mm for the water quality control depth when control rate is 80% and it takes 2~3 mm when control rate is 60%.Based on the daily water balance model,the rainfall data from 1985 to 2014 of Handan was analyzed,the effects of the rainfall characteristics,roof catchment area,the rainwater supply scheme on the storage facilities volume was discussed and the water supply reliability of roof rainwater utilization system under the different conditions were analyzed to put forward the optimal design scheme of rainwater utilization system facilities detention volume in this paper.The judgment methods of the roof rainwater utilization system peak control functions were put forward by building the roof rainwater utilization system peak runoff control model.Peak flow and peak time under different volume capture ratio of annual rainfall and different recurrence interval were studied: peak runoff decay time reaches 3.75~9.91 min when the total annual runoff control rate are 70%,75%,80%,85%,the peak runoff control rate of per unit area reaches 8.86%~36.82%. |
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