Stormwater quality calibration by SWMM: A case study in Northern Spain

Abstract

This article presents an application of the Storm Water Management Model (SWMM) in order to predict the pollution in rainy weather in a combined sewer system catchment in Santander, Spain. Suspended solids (SS), chemical oxygen demand (COD) and total Kjeldahl nitrogen (TKN) were measured at the exit of the catchment and these parameters were used for the calibration and validation of the model. The process of hydraulic and quality calibration is described and the values of the adjusted parameters are presented, comparing them with those obtained from other studies. The calibrated model simulated accurately the hydrograph's shape and the time of presentation of the peak flows. The accuracy of adjustment of the volume was 96%. As for the quality validation, the accuracy of adjustment among the total simulated loads of SS, COD and TKN, and those measured at the end of the rainfall events were 93, 95 and 78% respectively, confirming the accurate confirming the relative accuracy of the model in the prediction mode. The phenomenon of the first flush was analysed, and it was determined that 65, 57 and 54% of the polluting loads of COD, SS and TKN respectively, were swept along by the first 30% of the volume in the rainfall events used for the calibration of the model.

Urban Runoff Characteristics in Combined Sewer Overflows (CSOs): Analysis of Storm Events in Southeastern Spain

“…The Horton equation was used for infiltration modeling. Values adopted are in accordance with soil characteristics and with those proposed in the literature [21,22]. The maximum infiltration, f0, is around 20 mm/h, while the minimum infiltration, fc, is 1 mm/h.…”

“…The Manning's roughness coefficients for pervious and impervious areas were used as calibration parameters of the model. Initial values were selected from the literature [21,22]: 0.02-0.045 for pervious areas and 0.01-0.015 for impervious areas. The Manning roughness coefficient for conduits varies from 0.011 to 0.013 depending on the pipe material.…”

“…For a proper design of sustainable sewer systems, hydraulic and quality modeling tools are utilized [8,19,21]. Hydraulic models, such as USEPA Storm Water Management Model (SWMM) [22], predict the runoff flow rate and volume from observed rainfall intensities with accuracy.…”

Assessing the Effects of Climate Change on Water Quantity and Quality in an Urban Watershed Using a Calibrated Stormwater Model

“…As mentioned previously, SWMM model outputs are sensitive to hydraulic width, imperviousness and depression storage depth [34,60], the first two parameters being positively correlated to peak flow, the latter, negatively correlated. Calibration of the Difficult Run watershed model was conducted by varying hydraulic width (the sub-catchment area divided by the maximum overland flow length), imperviousness and depression storage depth (a depth that must be filled prior to the runoff occurs) for 2010 data.…”

Coupling GIS with Stormwater Modelling for the Location Prioritization and Hydrological Simulation of Permeable Pavements in Urban Catchments

“…The delineation and modelling of urban catchments is a widely addressed topic in literature, which provides multiple evidence of the capability of GIS and stormwater models to reproduce their hydrological response with accuracy [21][22][23]. Hence, the methodology presented in this study finds application in the next step to these tasks; i.e., in situations in which the stormwater modelling of urban catchments has been calibrated and validated and their simulation for design return periods leads to high peak runoff rates in the subcatchments forming them and flooding in the nodes of their drainage networks.…”