A semi-analytical approach for drainage network sizing and verification

The design and verification of sewer networks are essential for urban water management, influencing flood risk mitigation and infrastructure resilience. Traditional methods often rely on oversimplified assumptions, such as neglecting surface runoff (Keifer and Chu, 1957) or using empirical parameters with little physical significance (Supino, 1947), leading to inaccurate drainage system sizing. Additionally, some approaches fail to fully exploit Intensity-Duration-Frequency (IDF) curves, missing critical insights for peak flow estimation (Chow, 1962). To overcome these limitations, this study proposes a semi-analytical approach that accurately models upstream runoff and optimally utilizes IDF curves through a variational method. This approach ensures more precise and efficient sewer network design by identifying critical peak inflow conditions while maintaining computational speed and transparency. Overall, the proposed methodology provides a reliable alternative to traditional techniques, enhancing sewer network performance and adaptability to changing urban and climatic conditions.