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Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Urban Drainage Models:1D, 1D/1D and 1D/2DNuno Eduardo SimõesPhD Student at Imperial College London (ICL)Supervisor: Prof. Čedo Maksimović (ICL)Co-supervisor: Prof. Alfeu Sá Marques (UC)Junior Lecturer at University of Coimbra (UC)

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Depart. of Civil and Environmental EngineeringImperial College LondonProf. Č. Maksimović (ICL)Dr João Leitão (ICL)Prof.Alfeu Sá Marques (UC)Lipen Wang (ICL)Dr S. Boonya-aroonnet (ICL) Rui Pina (UC)Susana Ochoa (ICL)

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011CONTENTS1. Urban Floods2. Modelling3. Dual drainage4. Automatic Overland Flow Delineation5. Application6. Urban floods forecasting7. Customisation of drainage networks8. Monitoring system for calibration9. Conclusions

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Types of Urban floodingFluvialGround water floodingCoastalPluvial Surface Flooding

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Pluvial (Surface) FloodingExtreme rainfall events!

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Urban Flooding Poor drainage capacity of the sewer systemOverland flowPoor drainage managementOverloaded drainage systemEverything happens quickly: “flash floods”ForecastingManagement

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011CONTENTS1. Urban Floods2. Modelling3. Dual drainage4. Automatic Overland Flow Delineation5. Application6. Urban floods forecasting7. Customisation of drainage networks8. Monitoring system for calibration9. Conclusions

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Urban Pluvial Flooding

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Physically based modelling Realistic presentation of the terrain and ofthe physical features of the urbaninfrastructure Use of conservation principles / equations Spatially distributed systems and modellingprinciples

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Saint-Venant Equations A Q 0 t x1 Q1 Q2 h g ( So S f ) g{ {A tA xA x 3 {{bedfriction1424local accelerationpressureslopeconvective accelerationslopeDiffusion wave equationKinematic Wave A Q 0 t x A Q 0 t x h ( So S f ) xSo S f 0

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011KinematicwaveDiffusivewaveAccount for downstreambackwater effects and flowreversalAttenuation of flood wavesNoYesDynamic wave(Saint Venantequations)YesNoYesYesAccount for flow accelerationNoNoYes

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011SurchargePreissman SlotInteraction with surface

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Virtual reality in modellingThis was “state of the art” for yearsVirtual reservoirin the citycentre ΠPiezometric line

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011CONTENTS1. Urban Floods2. Modelling3. Dual drainage4. Automatic Overland Flow Delineation5. Application6. Urban floods forecasting7. Customisation of drainage networks8. Monitoring system for calibration9. Conclusions

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Pluvial Flooding – Dual Drainage ConceptEffective ub-surfacecomponentSewer flow

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Dual drainage concept, pond delineation and link with network0712Legend:84Subcatchment3DepressionFlooded area0561Total rainFlow in the sewerOverflow from depressionSurface runoffEffective rainOutflow to the surface23

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011DEMs and Urban Flood Modelling Dual-drainage concept (1D/1D and 1D/2D) Sewer system (manholes and pipes). Overland system (depressions and flow paths). 1D overland flow modelling Overland system consists of nodes (ponds) andlinks (flow paths), generated using DEM. 2D overland flow modelling Surface divided into small elements (squares orirregular triangles)

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Urban Flood Modelling1D/1D1D/2D

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Flow directions can alternate duringan extreme rainfall event Surface runoff enters drainage system. Surcharges from manhole.HHHa)b)c)

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011CONTENTS1. Urban Floods2. Modelling3. Dual drainage4. Automatic Overland Flow Delineation5. Application6. Urban floods forecasting7. Customisation of drainage networks8. Monitoring system for calibration9. Conclusions

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011AOFD - Automatic Overland Flow DelineationPond 3(ii)(i)Pond 2Manholes(v)Pond 4(iv)(vii)(iii)Manholes(vi)Pond 121

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011AOFD METHODOLOGY Tool for analysis and generation ofoverland network and automaticallyquantifying hydraulic parametersfor simulation model of pluvialurban flooding Based on Digital Elevation Modelinformation Nodes: ponds and associatedstorage capacity Links: pathways computedgeometry Interactions between the overlandflow and sewer systemsDEM Building layerOverland Network

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Overland Network of Cranbrook Catchment

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011CONTENTS1. Urban Floods2. Modelling3. Dual drainage4. Automatic Overland Flow Delineation5. Application6. Urban floods forecasting7. Customisation of drainage networks8. Monitoring system for calibration9. Conclusions

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Application – Coimbra, Portugal25

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/20119 June 2006Duration5 (min)10 (min)15 (min)30 (min)45 (min)Intensity (mm/h)122.476.872.461.647.6Return Period10820 505026

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Results1D Overland networkSewer System27

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011ResultsDepth level in a pipe upstream the flooded areaFlow in a pipe upstream the flooded areaNot surchargedBut we have pictures with flood!28

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011CONTENTS1. Urban Floods2. Modelling3. Dual drainage4. Automatic Overland Flow Delineation5. Application6. Urban floods forecasting7. Customisation of drainage networks8. Monitoring system for calibration9. Conclusions

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Urban flood forecasting Time available is one of the critical aspects of floodforecast modelling AIM: predict in 15 minutes the flood magnitudeand extension that might occur for the following 3hours.– Short term rainfall forecast– Runoff surface flood

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Are the advanced models (1D/1D and 1D/2D)adequate to predict urban flooding, i.e. fastenough to satisfy real time prediction?Fast Flood forecast with high accuracy and reliabilitycan be achieved by:– Computational techniques (better hardware)– Customisation of the catchment’s area andnetwork characteristics (our focus)

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011CONTENTS1. Urban Floods2. Modelling3. Dual drainage4. Automatic Overland Flow Delineation5. Application6. Urban floods forecasting7. Customisation of drainage networks8. Monitoring system for calibration9. Conclusions

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Simplification of NetworksPruning technique Exclusion of peripheral model links and their associated upstream nodese.g.: L 10m; Width 300mmMerging technique Grouping of similar consecutive model links based on their attributes (similarhydraulic capacity)e.g.: difference in dimension of consecutive links 100mmBoth techniques required catchments allocation and storage compensation

Second StrategyFirst StrategyNuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Complete(1D/1D)1D/1DmodelSewer system pruned and merged andcomplete overland model (1Dpm/1D)1D/1D model pruned and mergedtogether ((1D/1D)pm)Sewer system pruned and merged andoverland model pruned and mergedseparately (1Dpm/1Dpm)

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Simulation timeSimulation timefor rainfall A780 minReduction ofthesimulationtime1D1D193 s-(1D1D) pm122 s71s (-37%)1Dpm1D89 s104s (-54%)1Dpm1Dpm44 s149s (-72%)Type of network

Nuno Simoes, 2011 – Imperial 1DCollege/ 2DLondon - LEESU Seminar - 19/May/2011simulationHybrid1D/1D 1D/2Dsimulation1D SewerSimulation1D / 1Dsimulation

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Interaction between 1D Overland Networkand 2D Overland Network

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Pipe 1431.1Pipe 463.1

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/20111D1DHybrid1D2D

NunoSimoes, 2011 – Imperial College London - LEESU Seminar - 19/May/20110.60.4Inflow 01:1202:2403:3604:48TimeInflow from the overland networkand sewer systemLevel low [m3/s]2.5200:0001:1202:2403:3604:48TimeWater level in downstream node1.510.5000:0020.501:1202:2403:36TimeFlow in the pipe04:48

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Simulation Timeevent300min 30yrmodel1D1DHybrid1D2D[hh:mm:ss] vs 1D1D00:01:4600:04:31156%00:45:232469%vs hybrid905%300 1D1Dmin Hybrid100 yr 1D2D00:02:1100:05:2001:11:10144%3160%1234%300 1D1Dmin Hybrid200yr 1D2D00:04:4000:05:4901:16:0525%1530%1208%

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011CONTENTS1. Urban Floods2. Modelling3. Dual drainage4. Automatic Overland Flow Delineation5. Application6. Urban floods forecasting7. Customisation of drainage networks8. Monitoring system for calibration9. Conclusions

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Monitoring System - Cranbrook 3 tipping bucket rain gauges, with 1-2 min data “sampling”. 1 pressure sensor for Roding River level monitoring. Real timefrequency: 5/10 min. 2 sensors for water depth measurement in sewers. Real timefrequency: 5/10 min. 1 sensor for water depth measurement in open channels(downstream boundary condition).

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Monitoring System - Coimbra 3 tipping bucket rain gauges 3 sensors for water depth measurement in sewers. 1 sensor for water depth measurement in the surface.RaingaugesLevelgauges

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011CONTENTS1. Urban Floods2. Modelling3. Dual drainage4. Automatic Overland Flow Delineation5. Application6. Urban floods forecasting7. Customisation of drainage networks8. Monitoring system for calibration9. Conclusions

Nuno Simoes, 2011 – Imperial College London - LEESU Seminar - 19/May/2011Conclusions Where the drainage system has adequate capacity itcan be modelled as 1D only; all models which have an overland flow componentrequire an accurate Digital Terrain Model (DTM) as aprerequisite for the quality and reliability; 1D-1D modelling is more time consuming to set up than1D-2D but it is considerably faster computationally torun;