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Lumped and distributed modelling of suspended solids in a combined sewer catchment in Santiago de Compostela (Spain). R. Hermida , JOSE ANTA , M. Bermúdez, L. Cea, J. Suárez & J. Puertas GEAMA Research Team Universidade da Coruña. INTRODUCTION.
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Lumped and distributed modelling of suspended solids in a combined sewer catchment in Santiago de Compostela (Spain) R. Hermida, JOSE ANTA, M. Bermúdez, L. Cea, J. Suárez & J. Puertas GEAMA ResearchTeam Universidade da Coruña
INTRODUCTION • Flow and Pollution Modelling in Urban Systems dust and dirt buildup washoff gully-pot processes sewer erosion - transport
OBJETIVES • Comparison of a lumped and distributed model for TSS in “El Ensanche” combined sewer catchment • Model developed with Infoworks CS 9.x • Ackers-White equation • KUL model • 10 rain event were used for model calibration. More details presented yesterday: “Mobilized pollution indicators in a combined sewer system during rain events” del Río et al.
MODEL DEVELOPMENT • Distributedmodel (del Río, 2011) • 316 subcathments: 183 streets, 128 roofs, 5 perviousareas • 7 km of pipes (150 – 1200 mm) • Lumpedmodel (Hermida, 2012)
BUILDUP Model parameters : Ps, K1 Model parameters : C1, C2, C3 WHASOFF
SEWER TRANSPORT MODELS Ackers & White (1996) Model parameter are fixed. Model variables: s, d50 KUL (Boutelegier and Berlamont, 2002) Too many model parameters (6 parameters). Model variables: s, d50
SEWER TRANSPORT MODELS KUL : Shields approach (Shizari and Berlamont, 2010) Shields number has to be re-evaluated in each time – step (not allowed in IF) Ota and Nalluri equation (2003) KUL equation as function of s, d50
SENSITIVITY ANALYSIS: POLLUTION MODEL • InfoWorksdoesn’tallowan easyimplementation of formal MC inference • Sensitivityanalysis of thedifferentInfworksqualitysubroutineswithMatlab. • MethodologyproposedbyKleidorfer (2009): • Local sensitivityanalysis • Global sensitivityanalysis • Graphicalmethods • Hornberger – Spear – Young
SENSITIVITY ANALYSIS RESULTS BUILDUP Buildup factor is more sensitivitythanthedecay factor Modelissensitivitytobothparameters WHASOFF Modelisalmostinsensitivityto C3coefficient and can be neglected C2is more sensitivitythan C1 Modelissensitivitytobothparameters SEDIMENT TRANSPORT MODEL d50is more sensitivitythanthespecificdensity s Modelissensitivitytobothparameters
MODEL CALIBRATION Hydraulic model calibration • 11 rainy days: NS=0.85 Pollution model calibration • Visual calibration: 3 events • Model validation: 7 events • Distributed model • Ackers – White • KUL (Ota & Nalluri) • Lumped model • Ackers – White • KUL (Ota & Nalluri)
CONCLUSIONS • Successful application of sensitivity analysis to determine the most relevant parameters for pollution modelling in InfoWorks CS • All the sensitivity tests shows similar results • Lumped model works better in terms of NS and EMC • Distributed model works better in terms of Cmax • KUL – Ota & Nalluri approach avoids the determination of a large number of model parameters • Ackers – White is more accurate than KUL approach for lumped model and viceversa.
www.geama.org/hidraulica THANKS FOR YOUR ATTENTION jose.anta@udc.es
SENSITIVITY ANALYSIS Hornberger – Spear – Young Method (Kleidorfer, 2009) • MC framework • Comparison of model outputs with a synthetic run with NS • Analysis of the distance of behavioral (NS>0) and non behavioral (NS<0) empirical cumulative pdf Nash-Sutcliffe Syntheticrun
BUILDUP HSY: Ps HSY: K1