Abstract
In numerical modelling of rainfall caused runoff in urban sewer systems an essential parameter is the hydrological reduction factor which defines the percentage of the impervious area contributing to the surface flow towards the sewer. As the hydrological processes during a rainfall are difficult to determine with significant precision the hydrological reduction factor is implemented to account all hydrological losses except the initial loss. This paper presents an inconsistency between calculations of the hydrological reduction factor, based on measurements of rainfall and runoff, and till now recommended literary values for residential areas. It is proven by comparing rainfall-runoff measurements from four different residential catchments that the literary values of the hydrological reduction factor are over-estimated for this type of catchments. In addition, different catchment descriptions are presented in order to investigate how the hydrological reduction factor depends on the level of detail regarding the catchment description. When applying a total survey of the catchment area, including all possible impervious surfaces, a hydrological reduction factor of approximately 0.5 for residential areas with mainly detached houses is recommendable - contrary to the literary recommended values of 0.7 - 0.9.
| Original language | English |
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| Title of host publication | 10th International Conference on Urban Drainage : 21-26 August 2005, Copenhagen / Denmark |
| Editors | Eva Eriksson, Hülya Genc-Fuhrman, Thorkild Hvitved-Jacobsen, Anna Ledin, Peter Steen Mikkelsen, Jes Vollertsen |
| Publisher | Institute of Environment |
| Publication date | 2005 |
| Pages | 1-8 |
| Chapter | 8 |
| Publication status | Published - 2005 |
| Event | International Conference on Urban Drainage - Copenhagen, Denmark Duration: 21 Aug 2005 → 26 Aug 2005 Conference number: 10 |
Conference
| Conference | International Conference on Urban Drainage |
|---|---|
| Number | 10 |
| Country/Territory | Denmark |
| City | Copenhagen |
| Period | 21/08/2005 → 26/08/2005 |