Urban drainage efficiency evaluation and flood simulation using integrated SWMM and terrain structural analysis.

Area of Science:

• Environmental Engineering
• Hydrology
• Urban Planning

Background:

• Urban drainage systems face challenges in accurately simulating pluvial flooding.
• Rainwater inlet limitations are often overlooked in traditional flood models.
• Understanding urban flood mechanisms is crucial for effective water management.

Purpose of the Study:

• To develop and validate an integrated model for urban drainage efficiency and pluvial flood simulation.
• To incorporate rainwater inlet restrictions into a Storm Water Management Model (SWMM).
• To compare the performance of the corrected model against a non-corrected overflow model.

Main Methods:

• Integrated SWMM with terrain structural analysis to create a corrected model.
• Calibrated the model using data from two historical flood events.
• Compared simulation results (flood peak, Nash efficiency) with an overflow model.

Main Results:

• The corrected model demonstrated reasonable accuracy with low relative error (0.27%-2.80%) and good Nash efficiency (0.3184-0.9504).
• Drainage efficiency varied significantly across units, influenced by rainfall intensity and surface depression storage.
• Identified two distinct urban flood types: infiltration excess and saturation excess.

Conclusions:

• The corrected model provides a more accurate simulation of pluvial flooding by accounting for inlet limitations.
• Surface drainage plays a vital role in overall urban drainage system efficiency.
• Accurate modeling distinguishing between infiltration and saturation excess floods is essential for optimizing drainage design and flood management.