Modeling the impacts of climate change and flooding on sanitary sewage system using SWMM simulation: A case study

Abstract

Climate change has several impacts on rainfall patterns, increasing surface runoff, leading to sewer flooding, and receiving water contamination. This study analyzed the effects of climate change and flooding on the Al-Shuhada Quarter sewer system in Samawah City, Iraq, using the Storm Water Management Model (SWMM). The sanitary system's performance was evaluated before and after the leaking of stormwater at different return periods of two, five, ten, and twenty-five years. The SWMM model was manually calibrated by changing the influential sub-catchment characteristic using modeled and measured discharges. NMSE (0.123) and R (0.86) values were within the limits and proved that the model is valid. Evaluation results indicated that the system operated very well at dry weather flow but flooded at some locations during the leaking of stormwater at wet weather flow. As a response to climate change, changing return period from 2 to 25 years showed an increase in sanitary sewage system flooding volume and percentage of flooding manholes from 2504 m3 to 10% to 8868 m3 and 24%, respectively. By contrast, proposing the addition of extra two sewer lines has highly reduced the flooding events. To conclude, SWMM was a very powerful tool in predicting flooding volumes and locations at different rainfall intensities, and it assessed the capability of the proposed solutions to minimize flooding.

Keywords

• Climate change
• Flooding
• Return period
• Samawah
• Sanitary sewage system
• SWMM