modelling of pollution dispersion in natural stream during dry period

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Modelling of pollution dispersion in natural stream during dry period. Yvetta Velskov Institute of Hydrology SAS, Racianska 75, 831 02 Bratislava, Slovakia e-mail: veliskova@uh.savba.sk . Drought consequences environmental economic social. reduction of water quality. - PowerPoint PPT Presentation

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• Modelling of pollution dispersion in natural stream during dry period

Yvetta Velskov

Institute of Hydrology SAS, Racianska 75, 831 02 Bratislava, Slovakia

e-mail: veliskova@uh.savba.sk

• Environmental problemsWater pollutiondetermination of transport, dispersion and self-purifying characteristics of channels, optimum location of outlet structures in streams, delineation of mixing zones, prediction of spreading of accidental contaminant waves, etc.determination of pollutant distribution in natural streams in which the bed stream roughness, as results of flow conditions during low flows, forcefully impacts on a flow structure Mathematical and numerical modelling

• Dead zone model - schemethe mass transfer across the main flow and dead zone interface is proportionalto the concentration difference across them and to the discharge velocity

• The influence of dead zones was formed to the equations, which represent the conception: transported mass pollutant from the main flow (with the concentration C) gets into a side or a bottom dead zones as into a mixing tank; after that pollutant is mixed within the tank volume and then is exported back to the main flow zone with concentration CDZ .

The residence time of the fluid in the tank depends onthe mass exchange coefficient between the dead zones and the main flow and also on ratio of interfacial area to the dead zone volume.

• numerical modelscondition for applicationrange of input datarate of precisionetc.two-dimensional model

• Hydrodynamic approachc - mass concentration of pollutant [kg.m-3], h - depth [m], t - time [s], x,y,z - longitudinal, transverse and vertical coordinates [m], u,v,w - depth-averaged longitudinal, transverse and vertical velocities [m.s-1], x, y, z - longitudinal, transverse and vertical dispersion coefficients [m2.s-1] Input data: geomorphological characteristics of river, data connected with discharge and water level regime dispersion characteristics at simulated part of river data about pollution sources + influence of dead zones

• Model MODI: 2-D simulation model for determination of pollutant transport in natural (non-prismatic) channels based on the solution of advection-diffusion equation simulates under conditions of steady flow in non-prismatic channels possibility of simulation:arbitrarily situated unsteady sources of pollutioninfluence of dead zonesself-purification effectInput data:geometric characteristics of cross-sections and velocity profiles in selected location of computed part of streamquantity and location of pollutant sourcescoefficients of transverse dispersionself-purification coefficientdiffusion coefficient with dead zones and the interfacial area between the main flow and dead zones (the volume of dead zones)

• the mass exchange coefficient between the dead zones and the main flow (from 0.003 m2s-1 to 0.03 m2s-1),the interfacial area of dead zones (from 10% to 30% of active part) and their volume (from 20% to 50% of active part)

• dz eps Amz Vmz T

Graf1

00000.260770.171720.117060.193950.16770.10580.084840.06887

0.0207267830.173351280.0659488560.0207267830.907420.518960.35050.238130.51950.31870.25270.2136

0.325975770.457873490.348586810.109286681.39580.892380.586010.330.82060.52830.41390.3513

1.76554511.78815611.04576040.676446841.82281.20540.85050.561821.2030.76350.60620.4985

3.35773894.64468372.9865412.00672952.28091.42991.08960.745291.5940.99910.79220.6632

6.0842536.3668915.43041723.88156122.65811.52681.22140.913492.0221.2590.9630.8148

6.84737555.66971745.95423965.60376853.22111.78771.33841.07032.3911.461.1380.9772

4.38277253.291795.7563935.56043073.68122.06281.55561.1572.7451.6831.3321.129

1.80888291.5488564.51467035.21184394.12332.28731.68311.33192.5661.9051.4951.273

0.218573350.348586812.26675643.31440114.53322.5631.83961.53582.4041.6711.3011.116

0.0207267830.15262450.697173621.5262454.87822.82151.98591.38322.2221.4311.1060.9674

000.239300130.478600274.44833.09142.22871.28042.0261.1920.94330.8197

0.109286680.0866756393.99433.26582.07441.23511.7790.97940.77820.6616

0.0207267830.0207267833.80233.06311.92381.11421.6110.73870.59860.4967

003.31152.81251.78430.90771.4020.49380.42860.3323

2.91582.5221.59350.778271.1970.250.2660.1825

2.42692.20891.39260.653480.92610.1042

2.04542.14571.23040.605370.751

1.58931.82461.150.492460.3936

1.41491.51020.953990.3911

1.0131.21250.770.30286

0.671820.992910.60390.11823

0.406010.746760.48711

0.337650.3611

T1=1000s

T2=2000s

T3=3000s

T4=4000s

dzl1020T1

dzl1020T2

dzl1020T3

dzl1020T4

dzh1020T1

dzh1020T2

dzh1020T3

dzh1020T4

distance [m]

concentration [mg/l]

mz0-digit

X [m]c [mg/l]T=1000s

794.5410.000

853.1480.021

900.8710.326

920.9651.766

949.4313.358

997.9916.084

1046.5516.847

1095.1114.383

1143.6711.809

1201.4400.219

1250.0000.021

1298.5600.000

1976.7250.000T=2000s

2035.3320.173

2063.7980.458

2103.1481.788

2150.8714.645

2199.4316.367

2247.9915.670

2306.5983.292

2345.1111.549

2374.4140.349

2402.8800.153

2461.4870.000

3071.8350.000T=3000s

3168.9550.066

3217.5150.349

3256.0281.046

3294.5412.987

3353.1485.430

3372.4055.954

3430.1745.756

3449.4314.515

3508.0382.267

3546.5510.697

3575.8540.239

3605.1570.109

3643.6710.021

3672.9740.000

4254.0190.000T=4000s

4311.7880.021

4351.1390.109

4399.6990.676

4447.4212.007

4495.9813.882

4544.5415.604

4593.1015.560

4603.1485.212

4660.9183.314

4699.4311.526

4758.0380.479

4796.5510.087

4845.1110.021

4912.9270.000

mz0-digit

T1=1000s

T2=2000s

T3=3000s

T4=4000s

vzdialenos [m]

koncentrcia [mg/l]

mz1020m_v

xcT=1000sxcT=2000sxcT=1000sxcT=2000s

750.000.2608Amz=0,113500.171725300.1677Amz=0,113500.1058

900.000.9074Vmz=0,219600.518966300.5195Vmz=0,214800.3187

920.001.3958DIFmz=0,00320700.892386800.8206DIFmz=0,0315500.5283

930.001.822820901.20547201.20316100.7635

940.002.280921001.42997601.59416600.9991

950.002.658121101.52688002.02217101.259

970.003.221121201.78778302.39117501.46

980.003.681221302.06288702.74517901.683

990.004.123321402.28739902.56618501.905

1000.004.533221502.56310002.40420201.671

1010.004.878221602.821510102.22220601.431

1070.004.448321803.091410202.02620901.192

1080.003.994321903.265810401.77921200.9794

1090.003.802322503.063110501.61121500.7387

1100.003.311522602.812510601.40221900.4938

1110.002.915822702.52210701.19722400.25

1120.002.426922802.208910900.9261

1130.002.045422902.145711000.751

1140.001.589323001.824611300.3936

1150.001.414923101.5102

1160.001.01323201.2125xcT=3000sxcT=4000s

1170.000.6718223300.9929122100.0848430900.06887

1180.000.4060123400.7467623700.252732700.2136

23700.3376524500.413933600.3513

25200.606234400.4985

xcT=3000sxcT=4000s25800.792235100.6632

1970.000.1170625700.1939526300.96335700.8148

2690.000.350533700.2381326801.13836300.9772

3110.000.5860138300.3327401.33236901.129

3240.000.850542200.5618228001.49537601.273

3270.001.089644100.7452930401.30140501.116

3280.001.221444500.9134930901.10641000.9674

3290.001.338444701.070331200.943341400.8197

3310.001.555644801.15731600.778241900.6616

3320.001.683145101.331932000.598642400.4967

3330.001.839645401.535832400.428643000.3323

3340.001.985946101.383232900.26643700.1825

3370.002.228746201.280433700.1042

3430.002.074446301.2351

3440.001.923846401.1142

3450.001.784346600.9077

3460.001.593546700.77827

3470.001.392646800.65348

3480.001.230446900.60537

3490.001.1547000.49246

3500.000.9539947100.3911

3510.000.7747200.30286

3520.000.603947600.11823

3530.000.48711

3540.000.3611

mz1020m_v

0000

0.0207267830.173351280.0659488560.020726783

0.325975770.457873490.348586810.10928668

1.76554511.78815611.04576040.67644684

3.35773894.64468372.9865412.0067295

6.0842536.3668915.43041723.8815612

6.84737555.66971745.95423965.6037685

4.38277253.291795.7563935.5604307

1.80888291.5488564.51467035.2118439

0.218573350.348586812.26675643.3144011

0.0207267830.15262450.697173621.526245

000.239300130.47860027

0.109286680.086675639

0.0207267830.020726783

00

T1=1000s

T2=2000s

T3=3000s

T4=4000s

dzlT1

dzlT2

dzlT3

dzlT4

dzhT1

dzhT2

dzhT3

dzhT4

distance [m]

concentration [mg/l]

mz1020v

xcT=1000sxcT=2000s

5300.1677Amz=0,113500.1058

6300.5195Vmz=0,214800.3187

6800.8206DIFmz=0,0315500.5283

7201.20316100.7635

7601.59416600.9991

8002.02217101.259

8302.39117501.46

8702.74517901.683

9902.56618501.905

10002.40420201.671

10102.22220601.431

10202.02620901.192

10401.77921200.9794

10501.61121500.7387

10601.40221900.4938

10701.19722400.25

10900.9261

11000.751

11300.3936

xcT=3000sxcT=4000s

22100.0848430900.06887

23700.252732700.2136

24500.413933600.3513

25200.606234400.4985

25800.792235100.6632

26300.96335700.8148

26801.13836300.9772

27401.33236901.129

28001.49537601.273

30401.30