Simplifying impact of urban development on sewer systems

Area of Science:

• Environmental Engineering
• Urban Hydrology
• Water Resource Management

Background:

• Evaluating urban development's impact on sewer systems often involves complex urban drainage models.
• Directly linking urban development to drainage models is challenging for routine engineering practice.

Purpose of the Study:

• To propose a simplified, practical method for assessing the impact of paved urban areas on sewer system design rainfall.
• To establish a direct relationship between changes in impervious areas and the return period (RP) of design rainfall events.

Main Methods:

• Developed a near-quadratic relationship to translate paved area changes into RP variations.
• Utilized 250 virtual and two real-world case studies with hydrodynamic simulations for method development.
• Validated the method on a small catchment, comparing system performance and redesigned pipe diameters.

Main Results:

• The developed formula offers a straightforward way to adjust design rainfall return periods based on imperviousness.
• The method is compatible with current engineering design guidelines.
• The approach provides a tool for communicating the effects of impervious area changes to the public.

Conclusions:

• The proposed simplified method offers a feasible alternative to complex modeling for everyday engineering practice.
• While simplifications introduce uncertainties, they are comparable to existing uncertainties in future urban development predictions.
• This approach significantly improves upon current engineering practices for assessing urban development impacts on drainage systems.