A very common type of sewer system in old urban areas is the combined sewer system (CSS), a network of pipes that collects both stormwater and wastewater and expels excess untreated water volumes into nearby water bodies. To protect city dwellers from the alterations to the hydrological cycle and its consequences (i.e., flooding and exposure to pollutants such as viruses, chemicals, and suspended solids carried by runoff), sewer systems collect and convey stormwater away from cities ( USEPA, 2014). Impervious surfaces, such as concrete or asphalt, prevent infiltration, encourage urban runoff, preclude natural groundwater recharge, and increase the occurrence of flash flooding ( WMO and GWP, 2008 Huong and Pathirana, 2013), among other negative impacts. Land cover change from its natural state to impervious surfaces resulting from urbanization introduces an array of disturbances to the hydrological cycle ( Saier, 2007). This case study demonstrates the regional CSO challenges posed by climate change and supports the use of GI as a mitigation strategy. The simulation results show that (1) current 100-year events generate CSO volumes similar to predicted 50-year events (2) CSO volumes could increase by 11–73% in 2070–2099 compared to 1970–1999 when no GI intervention is performed and (3) the installation of PP can reduce 2–31% of future CSO volume. This paper used the Intensity-Duration-Frequency (IDF) curves for current (1970–1999) and future (2070–2099) design rainfall scenarios, with four rainfall durations (1, 6, 12, and 24 hours) and four return periods (2, 10, 50, and 100 years). Using the Storm Water Management Model (SWMM), the performance of PP as a CSO abatement strategy was studied for the city of Buffalo, New York, USA.
![pcswmm vs. epa swmm pcswmm vs. epa swmm](https://www.chijournal.org/images/journal/C402-7.jpg)
However, an understanding of the impact of climate change on CSO events and the effectiveness of GI practices is crucial for designing sustainable urban stormwater management systems. The installation of Green Infrastructure (GI) such as Porous Pavements (PP) is a resilient approach to mitigate CSO events. The impact of climate change on precipitation may result in an increase in the frequency and magnitude of heavy precipitation events, with a corresponding increase in CSO discharges.
![pcswmm vs. epa swmm pcswmm vs. epa swmm](https://www.mdpi.com/water/water-08-00511/article_deploy/html/images/water-08-00511-g002.png)
The results demonstrate that OSTRICH-SWMM is a promising tool for automatic calibration of SWMM models.Andrew Roseboro 1, Maria Nariné Torres 1,2 *, Zhenduo Zhu 1 and Alan J. The Pareto front for the case study was obtained using a multi-objective calibration algorithm and this allowed for evaluating tradeoffs between the peak flow and total volume criteria. A catchment in Buffalo, NY was selected as a case study and was calibrated according to two competing criteria: (1) minimizing errors in simulated peak flow, and (2) minimizing errors in total flow volume. The newly developed OSTRICH-SWMM is an open-source tool with dozens of parallelized optimization algorithms.
PCSWMM VS. EPA SWMM SOFTWARE
In this study, SWMM was integrated with the Optimization Software Tool for Research Involving Computational Heuristics (OSTRICH) to perform single- and multi-objective automatic calibration.
![pcswmm vs. epa swmm pcswmm vs. epa swmm](https://i1.wp.com/swmm5.org/wp-content/uploads/2016/09/image00419.jpg)
![pcswmm vs. epa swmm pcswmm vs. epa swmm](https://i.ytimg.com/vi/ThQZtCGu4rQ/maxresdefault.jpg)
Consequently, model calibration is a challenging task. A typical SWMM project has hundreds or thousands of sub-catchments and more than 20 parameters associated with six different physical processes for each sub-catchment. The USEPA (United States Environmental Protection Agency) Storm Water Management Model (SWMM) is one of the most widely used numerical models to simulate urban runoff and drainage.