0921 Urban Hydrology Study SHS

Purpose of the Study

Important for a cost-effective, efficient and approvable stormwater treatment is the overall view of the system of catchment area, stormwater treatment and sewage treatment plant as well as their mutual coordination, especially also the assumption of realistic, plausible values for sealed areas, population figures and wastewater and infiltration water flows. This can best be achieved with a comprehensive examination of the entire system. We call this an urban hydrology study, a planning tool that is superior of the general sewerage plan.


  • definition of a time plan horizon
  • determination of areas, careful estimate of realistic growth
  • determination of number of inhabitants
  • determination and definition of further key figures for the actual and planning
  • status (e.g. wastewater and infiltration water flow)
  • determination of infiltration inflow according to the ‘sliding minimum method’
  • inspection of CSOs and CSO tank structures
  • extensive discussion with the operating personnel
  • estimation of precipitation load by synthetic long-term rain series
  • calculation of emissions system by numeric quantity-quality simulation
  • determination of the allowed imission capacity of the receiving waters
  • matching of flow to the wastewater treatment plant with the flow from the stormwater tanks
  • comparison of several planning variants, minimization of emissions
  • cost-benefit comparison