water in the cities

In the Netherlands different design practices exist for sewer systems and free surface water systems.Sewer systems are designed with design events with a return period of one or two years, while open water systems with a return period of 100 years. Particularly in the cases where the sewer system and the open water system are integrated, the design is unclear. The prescribed sewer design events are insufficient for use within open water systems. For this reason, a series simulation is suggested: the series of rainfall which is the basis of the design event.

This series contains 10 years of 5-minute rainfall data. Simulating this series with an integrated model results in T=1 and T=2 water levels. To derive the T=100 water levels in the open water system, a series simulation may be performed using the 1906-2002 hourly rainfall data. This long simulation requires a simplified sewer network in the integrated model.

To prevent flooding problems in the urban area, Real-time Control (RTC) becomes more and more popular. With RTC it is possible to make optimal use of the available structures to prevent flooding and / or CSOs. A pilot study has been performed with a SOBEK sewer model in combination with TU Delft’s COMPOSER RTC model.

more information

For more information, please contact Klaas-Jan van Heeringen or Elgard van Leeuwen.