Design rules and impact assessment for source control measures based on continuous long-term simulations

In recent years, more emphasis has been put on source control measures in order to reduce the peak runoff from urban areas during wet weather conditions. This involves the construction of upstream storage and infiltration facilities and rainwater tanks for reuse in households and the revaluation of ditches. Because of the long emptying times of source control facilities, a long antecedent period of rainfall influences the design. In addition, these facilities most often have an outflow which is not linearly varying with the storage. Because of the high variability of the rainfall, the required storage volumes can therefore only be assessed well if continuous simulations with long rainfall series are performed. Based on long-term simulations design rules have been set-up for source control measures in Flanders.