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DSD-INT 2015 - Estimation of the flushing capacity in estuaries - javier f. barcena

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Estimation of the flushing capacity in estuaries

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DSD-INT 2015 - Estimation of the flushing capacity in estuaries - javier f. barcena

  1. 1. Estimation of the flushing capacity in estuaries according to the temporal variations of the main forcing and the spatial variations of the geometry and bottom topography 4th November, 2015 Javier F. Bárcena* (barcenajf@unican.es), Javier García-Alba, Andrés García, César Álvarez
  2. 2. 2 CONTENTS 1. Motivations 2. Objectives 3. Methodology 4. Application 5. Conclusions Suances Estuary
  3. 3. WHY THIS STUDY? Flushing time  The amount of time that it takes to effectively flush a confined region, being the most important physical influence on water quality in the system  We have to analyze the water circulation for zoning the water bodies and minimizing the environmental damage anthropic pressures Water management Water monitoring Development of useful tools to assess! HOW? Industrial Urban Overflow Suances Estuary ¯Cantabria 1. MOTIVATIONS
  4. 4. 4 CONTENTS 1. Motivations 2. Objectives 3. Methodology 4. Application 5. Conclusions Suances Estuary
  5. 5.  The final aim is to develop and apply a methodology for the calculation of water renewal on estuaries in order to use the obtained results for water management and water monitoring  The propose methodology has to: o consider the temporal variability of the major forcing o preserve the geospatial variations of the model domain o identify the major forcing in the study area 2. OBJECTIVES
  6. 6. 6 CONTENTS 1. Motivations 2. Objectives 3. Methodology 4. Application 5. Conclusions Suances Estuary
  7. 7. FLUSHING TIME CALCULATION  DELFT3D-FLOW (Hydrodynamics)  Local Flushing Time described in Jouon et al., 2006 ·eCC γ·t (o)(t)    1LFT  3. METHODOLOGY Local Flushing Time Flushing Lag
  8. 8. 8 3. METHODOLOGY t %M(t) M(t) = 37% M(t)=37%=e-1 2) FT calculation 3) FT sensitivity analyses 4) Final FT Velocity fields Boxes division BOX 4 BOX 6 BOX 1 BOX 2 BOX 3 BOX 5 BOX 7 BOX 8 9BOX 8 1   i iBOX BOX 4 BOX 6 BOX 1 BOX 2 BOX 3 BOX 5 BOX 7 BOX 8 9BOX 8 1   i iBOX BOX 1 BOX 2 BOX 3 BOX 5 BOX 7 BOX 8 9BOX 8 1   i iBOX Spatial analysis Forcing analysis1) Hydrodynamic forcing analyses River flow, tidal amplitude, initial phase and depth  Approach described in Bárcena et al., 2012 METHODOLOGICAL APPROACH
  9. 9. 9 CONTENTS 1. Motivations 2. Objectives 3. Methodology 4. Application 5. Conclusions Suances Estuary
  10. 10. SU1 SU2 SU3 SU4 SU5 Shallow, narrow, macrotidal, intertidal flats  High variability tide and different spatial behaviors 0.7 – 5.1 m tidal ranges 389 ha surface area 5.5 km long 150 m mean widthSaja-Besaya River Basin Saja River Besaya River Cantabric Sea ¯ Suances Estuary Small surface area, short length, steep slope, reduced time of concentration  High variability river flow 967 m2 catchment area 23 m3/s annual mean flow <24 h time of concentration 4. APPLICATION Cantabria STUDY AREA
  11. 11. 11 PLAN VIEW SIDE VIEW MESHGRID 4. APPLICATION CELLSIZE INSIDE ESTUARY=4-30 m
  12. 12. PHYSICAL PARAMETERS CALIBRATED VALUES HZTAL EDDY VISCOSITY (VH) SIZE VARIABLE (k∙u∙∆x) HZTAL EDDY DIFFUSIVITY (DH) SIZE VARIABLE (DH=VH/0.7) VTCAL EDDY VISCOSITY (VV) k-EPSILON VTCAL EDDY DIFFUSIVITY (DV) k-EPSILON BOTTOM STRESSES DEPTH VARIABLE LATERAL STRESSES FREE-SLIP CONDITION MODEL SETUP 4. APPLICATION WATER DEPTH (m) MANNING (n) H≤-2.5 0.032 -2.5≤H<-2.0 0.028 -2.0≤H<-1.5 0.023 -1.5≤H<-1.0 0.020 -1.0≤H<-0.5 0.019 -0.5≤H<0.0 0.018 WATER DEPTH (m) MANNING (n) 0.0≤H<0.5 0.024 0.5≤H<1.0 0.026 1.0≤H<3.0 0.025 3.0≤H<-10.0 0.023 H>10.0 0.022 NUMERICAL PARAMETERS CALIBRATED VALUES NUMERICAL SCHEME CYCLIC TIMESTEP ∆t=0.1 min=6 s NUMERICAL FILTERS VERTICAL ARTIFICIAL MIXING WETTING AND DRYING THRESHOLD DEPTH < 0.1m
  13. 13. 13 CRITERIA NUMBER VALUES DEPTH 10 σ-LAYERS TIDAL PHASE 4 EBB/FLOOD = 0 m HIGH/LOW = ±1.46 m TIDAL RANGE 1 A50 = 1.46 m RIVER FLOW 5 Q0=0.7; Q10=3.4; Q50=12.1; Q90=51.6; Q100=561.2 m3/s FLUSHING TIME CASES 4. APPLICATION
  14. 14. 14 CRITERIA NUMBER VALUES DEPTH 10 σ-LAYERS TIDAL PHASE 4 EBB/FLOOD = 0 m HIGH/LOW = ±1.46 m TIDAL RANGE 1 A50 = 1.46 m RIVER FLOW 5 Q0=0.7; Q10=3.4; Q50=12.1; Q90=51.6; Q100=561.2 m3/s DEPTH 4. APPLICATION AVERAGED!
  15. 15. 15 TIDAL PHASE CRITERIA NUMBER VALUES DEPTH 10 σ-LAYERS TIDAL PHASE 4 EBB/FLOOD = 0 m HIGH/LOW = ±1.46 m TIDAL RANGE 1 A50 = 1.46 m RIVER FLOW 5 Q0=0.7; Q10=3.4; Q50=12.1; Q90=51.6; Q100=561.2 m3/s 4. APPLICATION AVERAGED!
  16. 16. 16 RIVER FLOW CRITERIA NUMBER VALUES DEPTH 10 σ-LAYERS TIDAL PHASE 4 EBB/FLOOD = 0 m HIGH/LOW = ±1.46 m TIDAL RANGE 1 A50 = 1.46 m RIVER FLOW 5 Q0=0.7; Q10=3.4; Q50=12.1; Q90=51.6; Q100=561.2 m3/s 4. APPLICATION 5 FT  OBJECTIVE  1 FT HOW? NOT-AVERAGED!
  17. 17. 17 FINAL FLUSHING TIME Annual Mean forcing FT=0.427 days=10.248 h 4. APPLICATION SS4 SS2 SS3 SS1 SS4=0.126 days=3.024 h SS3=0.267 days=6.408 h SS2=0.797 days=19.128 h SS1=0.349 days=8.376 h
  18. 18. 18 CONTENTS 1. Motivations 2. Objectives 3. Methodology 4. Application 5. Conclusions Suances Estuary
  19. 19. 5. CONCLUSIONS Methodology:  Preserving the temporal variability of the major forcing and the geospatial variations of the estuary  Identifies the principal forcing in the study area  Calculates a final FT which is more realistic than a FT evaluates with mean annual conditions of the forcing Applications:  Results could be useful for water management (characterize, assess or police)  Results could be useful for water monitoring (design optimization) Suances Estuary:  River flow is the main forcing for water circulation in the Suances Estuary and the main channel, becoming more significant in the innermost part  Tide is the main forcing for water circulation in the mouth and the intertidal flats  Water flushing time is almost independent of the forcing in the estuarine reach
  20. 20. 20 THANKS FOR YOUR ATTENTION Questions? Suances Estuary
  21. 21. Estimation of the flushing capacity in estuaries according to the temporal variations of the main forcing and the spatial variations of the geometry and bottom topography 4th November, 2015 Javier F. Bárcena* (barcenajf@unican.es), Javier García-Alba, Andrés García, César Álvarez

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