ECO LabECO Lab

MIKE11 WQ module

WQ Modelingwem.ait

What is ECO Lab (WQ)?

The new Process Module of DHI Software

WQ module deals with the chemical/biological transforming processes of compounds (e.g. oxygen depletion and ammonia levels as a result of organic/nutrient loadings)

Can also applied be in aquaculture for e.g optimizing the production of fish, sea grasses and mussels

Open equation solver for water quality and ecology in the water environment

Predefined templates or user defined templates Predefined - DO, temp, nitrogen, phosphorus, BOD, coliform,

bacteria, metals, algae, zooplankton, detritus, cohesive sediments, noncohesive sediment

User can define water quality constituents to be simulated

WQ Modelingwem.ait

State variables

State variables dissolved substances

particulate matter of dead or living material

living biological organisms

other components

State variables can either be transported by advection-dispersion processes based

on hydrodynamics

have a more fixed nature (e.g. rooted vegetation)

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State variables solution

Solution Parameters includes selection of the Integration Method for the coupled ordinary differential equations, 3 options Euler integration method

Runge Kutta 4th order

Runge Kutta 5th order with quality check

Update Frequency (time step) Depends on process being modeled

A large Update Frequency will decrease the precision (độ chính xác) as well as the CPU time

perform a sensitivity analysis on the Update Frequency before making the final selection

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Constants and forcings

Constants (in time) - Built-in Constants and User-specified Constants

Forcings (varying in time) Temperature, salinity, solar radiation and water depth

Built-in Forcings and User-specified Forcings

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Levels of model

Six model levels corresponding to different sets of state variables for the water quality and/or different descriptions ofthe transformation of the state variables in the river

Model level 1: BOD and DO A simple oxygen balance model, only including immediate

oxygen demand from degradation of BOD and re-aeration

Model level 2: BOD, with bed/sediment exchange and DO As model level 1, except that here re-suspension and

sedimentation are included in the calculation of the BOD balance, and a sediment oxygen demand is included in the dissolved oxygen balance

Model level 3: BOD, DO, and nitrification As for model level 1 with the addition of the ammonia / nitrate

balances, and the oxygen consumption from the nitrification process. No denitrification is assumed

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Levels of model

Model level 4: BOD, with bed/sediment exchange, DO, Nitrification and Denitrification Includes all processes from model levels 2 and 3: resuspension and

sedimentation are included in the calculation of the BOD balance, and the ammonia / nitrate balances, plus the oxygen consumption sediment oxygen demand and the nitrification process are included. Moreover, denitrification is included.

Model level 5: BOD and DO, including delayed oxygen demand BOD at this model level is split into three different fractions: dissolved

in the water phase, suspended in the water phase, and settled at the river bed. Degradation of the settled BOD fraction at the river bed gives rise to the delayed oxygen demand. This level does not include the nitrogen components ammonia and nitrate.

Model level 6: All processes Dissolved BOD, suspended BOD, BOD at the river bed, oxygen,

ammonia and nitrate. BOD is described as for level 5, and nitrogen components are described as for level 4.

Coliforms and phosphorus are optional at all model levels Wetlands processes can be included at level Nos. 3, 4 and 6

WQ Modelingwem.ait

Oxygen processes

Factors affecting the oxygen concentration Photosynthesis (O2

production)

Plant and animal respiration

Re-aeration (exchange with the atmosphere)

BOD degradation (decay) and nitrification (treated separately in MIKE11-WQ)

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Oxygen processes

A first estimate of the oxygen parameters: production, respiration and re-aeration constants can be carried out from measured diurnal variations of the oxygen concentrations

dC/dt = K2⋅(Cm-C)-R+P(t) C- O2 concentration (mg/l)

Cm - O2 concentration at saturation (mg/l)

R - respiration (g O2/m3/day or g O2/m

2/day)

P(t)- photosynthetic prod. (g O2/m3/day or g O2/m

2/day)

K2 – re-aeration constant (day-1)

t - time (day)

The oxygen production P(t) at night is nil, which means the respiration and re-aeration can be estimated from the night measurements

Tuned during calibration

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Degradation in the water phase

Degradation = K1BOD . Θ (T-To) . (DO2 / (K2 + DO2))

K1BOD = first order decay rate for dissolved BOD at

20oC Θ (T-To) - Arrhenius temperature coefficient for the

decay rate DO2 / (K2 + DO2) - half-saturation oxygen

concentration in the Michaelis­Menten expression describing the influence of oxygen in the BOD decay, K2, is shown, in the unit of g O2/m3. The BOD decay decreases at low O2 concentrations due to the depression of bacterial BOD degradation under anaerobic conditions.

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Re-aeration

Affected by: current velocity, river slope, water depth and temperature

K2 = a ub hc ld

K2 – re-aeration constant at 20°C (g O²/m²/day)

u - flow velocity (m/s)

h - water depth (m)

I - river slope

a, b, c, d – constants (use Thyssen expression, O'Connor Dubbins expression, Churchill expression, Custom expressions)

General guidelines:

• If Depth < 0.61m , use the Owens-Gibbs formula

• If Depth > 0.61m and Depth > 3.45 u2.5, use O’Connor-Dobbins formula

• Otherwise, use the Churchill formula

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Temperature modeling

Water temperature will vary throughout the year and even throughout the day, but it will not vary as much as the air temperature

The warmer the water, the less dissolved oxygen Computed as the difference between solar energy

input (only during light hours) and the energy loss due to emitted heat radiation (during night and day)

Defined by latitude (degrees) of the location of the river maximum heat radiation of the river (kJ/m²/hour) displacement of the maximum temperature of the

river before/after 12 noon (-ve/+ve hrs) emitted heat radiation from the river (kJ/m²/day)

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Temperature effect on degradation

Higher the temperature, the faster a given chemical reaction will proceed

Quantitatively this relationship between the rate a reaction proceeds and its temperature is determined by the Arrhenius Equation

MIKE11- WQ temp dependency is denoted by introducing Θ (T-To) in the degradation equation To - reference temperature is 20 °C

If Θ is set to be 1.07, the process rate doubles when temperature increases by 10 °C

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Nitrogen and Phosphorus

Nitrogen;

Ammonification, nitrification and denitrification

Uptake by plants and algae

Degradation of organic matter

Uptake by plants and algae

Phosphorus;

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Nitrogen contents

Nitrogen release from BOD decay

Uptake of ammonia by plants and bacteria

Modeling immediate oxygen demand (Model level 3 and 4) release of ammonia-nitrogen for the degradation of

organic matter (g NH4-N / g O2)

uptake of ammonia-nitrogen by the plants relative to the net photosynthesis (= photosynthesis -respiration) (g NH4-N uptake / g O2 released)

uptake of ammonia-nitrogen by bacteria relative to their uptake of oxygen (NH4-N uptake / g O2 used)

WQ Modelingwem.ait

Nitrogen contents

Modeling immediate and delayed oxygen demand (Model Level 6) release of ammonia-nitrogen for the degradation of

dissolved, suspended and sediments organic matter (g NH4-N / g O2)

uptake of ammonia-nitrogen by the plants relative to the net photosynthesis (= photosynthesis -respiration) (g NH4-N uptake / g O2 released)

uptake of ammonia-nitrogen by bacteria relative to their uptake of oxygen (NH4-N uptake / g O2 used)

WQ Modelingwem.ait

Nitrification and denitrification

Nitrification is the biological oxidation of ammonia into nitrate, via nitrite

Denitrification - nitrate is transformed into free nitrogen, which eventually escapes to the atmosphere due to its low water solubility

WQ Modelingwem.ait

Parameters to define nitrification or denitrification

Reaction n = 1 for an ordinary 1st order reaction

n = 0.5 for a 1/2- order reaction

Rate constant for the nitrification at 20°C If n = 1, rate constant =1/day

If n = 0.5, the unit is (mg/l)1/2/day

Arrhenius temperature coefficient for nitrification

Oxygen demand by nitrification (g O2 /g NH4+-N)

Only relevant to nitrification

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Phosphorus content and process

Content Input 1= phosphorus content in organic matter (g P /

g O2) originating from pollution sources, and in plants

Input 2 = uptake of phosphorus by plants per g O2

produced (net production = production – respiration)

Process Input 1= first order decay rate 20 °C

Input 2= Arrhenius temperature coefficient

Input 3= first order rate for the formation of particulate phosphorus from orthophosphate at 20 °C

Input 4= corresponding Arrhenius temperature coefficient is specified

WQ Modelingwem.ait

Total and Fecal coliform

The decay of coliforms is dependent on the light intensity in the water column, the temperature and the salinity

Coli decay = K .Ccoli . ΘT (T–20) . ΘS

SAL . ΘII

K = first order decay rates for fecal and total coliforms(at 20 ºC, total dark­ness and zero salinity)

Default K value are used based on experiments with water polluted with coli bacteria

ΘT (T–20) . ΘS

SAL . ΘII corrections for temperature,

salinity and light I = light intensity, calculated through light extinction

coefficient, SAL = measured salinity

WQ Modelingwem.ait

Biochemical and physical processes at a glance

-1

+1

-1

BODb

4

R0.066-1Respiration9

Pmax·cos[2π(τ/α)]-0.0661Photosynthesis8

K6·NO3e6-1Denitrification7

K4·NH3e41-1-Y1Nitrification6

B1-1Sediment DO demand5

S1·BODb/d1BOD resuspension4

K5·BODs/d-1BOD sedimentation3

Kb3·BODb-1BODb biodegradation2c

Ks3·BODs-1-1BODs biodegradation2b

Kd3·BODd-1-1BODd biodegradation2a

K2·(DOsat-DO)1Rearation1

[ML-3T-1]NO3NH3BODsBODdDOProcess*

Process rate65321WQ parameters

where BODd = dissolved BOD [ML-3]; BODs = suspended BOD [ML-3]; BODb = settled BOD [ML-3]; Kd3 = degradation rate constant for dissolved BOD [T-1]; Ks3 = degradation rate constant for suspended BOD [T-1]; Kb3 = degradation rate constant for settled BOD [T-1]; K5 = sedimentation rate for suspended BOD [LT -1]; d = mean river depth [L]; S1 = resuspension rate for sedimented BOD (zero, if the flow velocity or the concentration BODb are below critical values) [LT-1]; B1 = constant value of sediment oxygen demand (in addition to biodegradation of BODb) [ML-3T-1]; Y1 = yield factor for oxygen consumed by nitrification [-]; K4 = nitrification rate constant [T-1 or M 1/2L-3/2 T-1]; e4 = coefficient characterizing concentration dependence of nitrification (1 or 0.5) [-]; K6 = denitrification rate constant [T-1 or M1/2L-3/2T-1]; e6 = coefficient characterizing concentration dependence of denitrification (1 or 0.5) [-]; Pmax = maximum production at noon (zero during the night) [ML-3T-1]; τ = actual time of the day related to noon [-]; α = actual relative day length [-]; R = respiration rate [ML-3T-1]; * temperature dependence was omitted for clarity; Additional packages for phosphorous, eutrophication, heavy metals and sediment are not shown in the table

Demo and ProjectDemo and Project

Fish death in Chao Phraya River(11-13 March 2007)

WQ Modelingwem.ait

Problem

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2 Mar 2007 - UE35, a barge carrying 650 tons of raw sugar traveled to the Mitrpol sugar factory, Ang Thong Province

3 Mar 2007 - UE35 sank into the Chao Phraya river, start from 13.00 to midnight

10 Mar 2007 - Starting to salvage the craft

11-13 Mar 2007 - Fish killed in CPY river, especially at Pamok district (12 km d/s from the sink point)

Problem

QuestionQuestion

Is the barge accident responsible for fish death?

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Fish Killed (11-12 Mar 07)Bang Sadet Sub-District

Accident Point

Fish Killed(12-13 Mar 07)

Polluted Water

mg/l

DistancefromRiverMouth(km)

Non

thab

uri

Sam

lae

Sam

kok

Ban

g S

ai

Ban

g P

a-in

Ayu

tth

aya

Ban

g B

al Pa Mok,

Ang Thong

Observed DO in Chao Phraya River (13 – 23 March 2007)

WQ Modelingwem.ait

HydrodynamicsHydrodynamics

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Network: CPY-Network-OnlyCPY.nwk11

X-Section: CPY-XSection.xns11

Boundary: CPY-Only-Boundary2007.bnd11- Discharge_C13_2007.dfs0- Discharge_RamaVI_2007.dfs0- WL_FortChula_2007.dfs0

HD Parameters: CPY-HDPar.HD11

Simulation Period: 1 Jan 2007 – 20 Mar 2007

Time Step: 5 Minutes

Setup Files: CPY-Only_HD2007.sim11

Hydrodynamic simulation

WQ Modelingwem.ait

Chao Phraya Dam

Chao Phraya River Mouth

Pamok District(Chainage 109900)

Po Sa Sub-District(Chainage 112900)Fish Killed Area

Mitrpol Sugar Factory(Chainage 101700)

Bang Sai

Samkok

Bang Pa-in

River Network

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Cross Sections

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Hydrodynamic Boundary ConditionsHydrodynamic Boundary Conditions

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Hydrodynamic Parameters

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Hydrodynamic Results

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Network: CPY-Network-OnlyCPY.nwk11

X-Section: CPY-XSection.xns11

Boundary: CPY-Only-WQBC2007_BODSugar.bnd11

HD Parameters: CPY-HDPar.HD11

AD Parameters: CPY-ADPar_DX50ALL.AD11

WQ (EcoLab) Parameters: CPY-WQLevel1_DrySeason.ecolab11

Simulation Period: 20 Feb 2007 – 20 Mar 2007

Time Step: 3 Minutes

Water Quality Simulation

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BOD Loading from Sugar

Const. WQ Status

Water Quality Boundary Conditions

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Advection-Dispersion Parameters

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Water Quality Parameters

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Data: Observed DO during March 2007

Site: Chao Phraya River

Observed DO (mg/l)Location Chainage KM from D/S 13/03/2007 14/03/2007 15/03/2007 16/03/2007 17/03/2007 18/03/2007 19/03/2007 20/03/2007 21/03/2007 22/03/2007

PCD RID PCD RID PCD RID PCD RID PCD RID PCD RID PCD RID PCD RID PCD RID PCD RIDSamut Prakarn Samut Prakran Province 266980 6.00

Phra Pradaeng 258980 14.00Bangkok Khlong Toei 246980 26.00

Taksin Bridge 230980 42.00Memorial Bridge 226980 46.00Phra Pinkhlao Bridge 224180 48.80Krung Thon Bridge 219480 53.50RID Office (Samsen) 219000 53.98 2.40 2.08 2.59 1.90Rama VII Bridge 218480 54.50

Nonthaburi Nonthaburi Pier 210980 62.00 1.60Pak Kret 202980 70.00 3.60 2.93 3.58 3.36 3.20 3.22 3.44 1.20Nonthaburi (Nual Chawee) Bridge 194980 78.00 3.70 2.60Wat Hong Pathumawas 185500 87.48 3.60 3.20

Pathumthani Samlae 182980 90.00 4.49 3.40 4.49 4.08 4.03 3.00 4.06 4.30 3.72 3.94 4.00 5.00 2.80Wat Phi Lom 179980 93.00 3.70 3.00Samkok District 174980 98.00 4.50 3.90 4.20 3.80 4.00 4.20 2.80

Ayutthaya 3 km D/S from Bang Sai Arts and Crafts Center 165980 107.00 4.001 km D/S from Bang Sai Arts and Crafts Center 163980 109.00 3.00 2.20Bang Sai Arts and Crafts Center 162980 110.00 3.00 2.50 2.50 2.50D/S from RID Observed Station C.29 161980 111.00 4.47 3.60 3.73 3.20 3.21 1.74RID Observed Station C.29 161580 111.40 1.75 1.56 2.99Bang Sai Pier 157230 115.75 3.50 4.80 4.60 3.60Wat Choeng Len, Bang Sai District 157180 115.80 3.73 2.34 2.20 0.53 3.50 2.95 3.60 3.20 4.20 5.40 3.40Bang Krasun Sub-District, Bang Pa-in District 150560 122.42 3.77 1.25 3.42 5.60 5.05Wat Phoe, Ban Po Sub-District, Bang Pa-in District 146480 126.50 2.04 3.83 6.62 6.20 5.58Paper Factory, Bang Pa-in District 145000 127.98 0.80 4.50 2.80 6.50 4.30Bang Pa-in District 138840 134.14 5.00 4.50 0.30 2.73 4.70 5.75 6.70 5.50 5.35 5.30Petr Fort, Wat Panunchoeng 133000 139.98 4.30 0.90 0.85 4.55 4.75 5.20 6.12 5.14 5.41 5.10 3.00RID Observed Station C.35 125000 147.98 4.71 5.75 5.86 6.25 5.94 5.27Bang Bal District 118000 154.98 0.40 6.10 4.80Wat Chulamanee, Bang Bal District 116980 156.00 6.00 8.20 6.30 6.00 6.20

Ang Thong Wat Tha Sutthawas, Bang Sadet Sub-District, Pa Mok District 114980 158.00 5.89 5.60 7.10 5.07 6.20 6.37 6.60 5.39 6.00 5.78 6.0046 Moo 3, Bang Sadet Sub-District, Pa Mok District 113980 159.00 6.30 6.20 6.00Aquaculture Area, Moo 5, Bang Sadet Sub-District, Pa Mok District 112900 160.08 6.00 7.00 6.10 6.00 6.30Ayinotagara Factory, Pa Mok District 110100 162.88 6.30 5.53 5.57 5.64 5.26 5.40 5.26Paper Factory (1), Pamok District 110000 162.98 6.70Pamok District Office 109900 163.08 6.60 7.30 6.30 6.40 6.10Wat Chaeng, Bang Pakod Sub-District, Pamok District 101200 171.78 7.10 6.20Paper Factory (2), Po Sa Sub-district, Muang District 101500 171.48 6.60 6.10100 m D/S from Accident Point, Moo 1, Po Sa Sub-District, Muang District 101800 171.18 6.70 7.20 6.20Wat Ratchapuksee, Po Sa Sub-District, Muang District 101500 171.48 6.50 7.20 7.10 6.70

Observed DO in Chao Phraya River

WQ Modelingwem.ait

DO in Chao Phraya River (12 March 2007)

0.0

2.0

4.0

6.0

8.0

0306090120150180210240270

KM from River Mouth

DO

(m

g/l

)

Simulated

Observed (PCD)

Observed (RID)

Sam

ut P

rakr

an

Phr

a P

rada

eng

Khl

ong

Toe

i

Mem

oria

l Brid

ge

Ram

a V

II B

ridge

Pak

Kre

t

Non

thab

uri B

ridge

Sam

Kok

Ban

g S

aiA

&C

Cen

ter

Ban

g S

ai

Ban

g P

a-in

Wat

Pan

unch

oeng

Ban

g B

al

Acc

iden

tP

oint

Aquacultural Area,Bang Sadet Sub-District

Ayinotagara Factory

Pa Mok District

Water Quality Simulation Results

WQ Modelingwem.ait

DO in Chao Phraya River (14 March 2007)

0.0

2.0

4.0

6.0

8.0

0306090120150180210240270

KM from River Mouth

DO

(m

g/l

)

Simulated

Observed (PCD)

Observed (RID)

Sam

ut P

rakr

an

Phr

a P

rada

eng

Khl

ong

Toe

i

Mem

oria

l Brid

ge

Ram

a V

II B

ridge

Pak

Kre

t

Non

thab

uri B

ridge

Sam

Kok

Ban

g S

aiA

&C

Cen

ter

Ban

g S

ai

Ban

g P

a-in

Wat

Pan

unch

oeng

Ban

g B

al

Acc

iden

tP

oint

Aquacultural Area,Bang Sadet Sub-District

Ayinotagara Factory

Pa Mok District

Water Quality Simulation Results

WQ Modelingwem.ait

DO in Chao Phraya River (16 March 2007)

0.0

2.0

4.0

6.0

8.0

0306090120150180210240270

KM from River Mouth

DO

(m

g/l

)

Simulated

Observed (PCD)

Observed (RID)

Sam

ut P

rakr

an

Phr

a P

rada

eng

Khl

ong

Toe

i

Mem

oria

l Brid

ge

Ram

a V

II B

ridge

Pak

Kre

t

Non

thab

uri B

ridge

Sam

Kok

Ban

g S

aiA

&C

Cen

ter

Ban

g S

ai

Ban

g P

a-in

Wat

Pan

unch

oeng

Ban

g B

al

Acc

iden

tP

oint

Aquacultural Area,Bang Sadet Sub-District

Ayinotagara Factory

Pa Mok District

Water Quality Simulation Results

WQ Modelingwem.ait

DO in Chao Phraya River (20 March 2007)

0.0

2.0

4.0

6.0

8.0

0306090120150180210240270

KM from River Mouth

DO

(m

g/l

)

Simulated

Observed (PCD)

Observed (RID)

Sam

ut P

rakr

an

Phr

a P

rada

eng

Khl

ong

Toe

i

Mem

oria

l Brid

ge

Ram

a V

II B

ridge

Pak

Kre

t

Non

thab

uri B

ridge

Sam

Kok

Ban

g S

aiA

&C

Cen

ter

Ban

g S

ai

Ban

g P

a-in

Wat

Pan

unch

oeng

Ban

g B

al

Acc

iden

tP

oint

Aquacultural Area,Bang Sadet Sub-District

Ayinotagara Factory

Pa Mok District

Water Quality Simulation Results

WQ Modelingwem.ait

BOD in Chao Phraya River

0.0

5.0

10.0

15.0

20.0

0306090120150180210240270

KM from River Mouth

BO

D (

mg

/l)

03/03/2007 12:00:00

04/03/2007 12:00:00

05/03/2007 12:00:00

06/03/2007 12:00:00

07/03/2007 12:00:00

08/03/2007 12:00:00

09/03/2007 12:00:00

BOD in Chao Phraya River

0.0

5.0

10.0

15.0

20.0

0306090120150180210240270

KM from River Mouth

BO

D (

mg

/l)

10/03/2007 12:00:00

11/03/2007 12:00:00

12/03/2007 12:00:00

13/03/2007 12:00:00

14/03/2007 12:00:00

15/03/2007 12:00:00

16/03/2007 12:00:00

Water Quality Simulation Results

WQ Modelingwem.ait

BOD in Chao Phraya River

0.0

5.0

10.0

15.0

20.0

0306090120150180210240270

KM from River Mouth

BO

D (

mg

/l)

17/03/2007 12:00:00

18/03/2007 12:00:00

19/03/2007 12:00:00

20/03/2007 12:00:00

21/03/2007 12:00:00

22/03/2007 12:00:00

23/03/2007 12:00:00

BOD in Chao Phraya River

0.0

5.0

10.0

15.0

20.0

0306090120150180210240270

KM from River Mouth

BO

D (

mg

/l)

24/03/2007 12:00:00

25/03/2007 12:00:00

26/03/2007 12:00:00

27/03/2007 12:00:00

28/03/2007 12:00:00

29/03/2007 12:00:00

30/03/2007 12:00:00

Water Quality Simulation Results

WQ Modelingwem.ait

DO in Chao Phraya River

0.0

2.0

4.0

6.0

8.0

0306090120150180210240270

KM from River Mouth

DO

(m

g/l)

03/03/2007 12:00:00

04/03/2007 12:00:00

05/03/2007 12:00:00

06/03/2007 12:00:00

07/03/2007 12:00:00

08/03/2007 12:00:00

09/03/2007 12:00:00

DO in Chao Phraya River

0.0

2.0

4.0

6.0

8.0

0306090120150180210240270

KM from River Mouth

DO

(m

g/l)

10/03/2007 12:00:00

11/03/2007 12:00:00

12/03/2007 12:00:00

13/03/2007 12:00:00

14/03/2007 12:00:00

15/03/2007 12:00:00

16/03/2007 12:00:00

Water Quality Simulation Results

WQ Modelingwem.ait

DO in Chao Phraya River

0.0

2.0

4.0

6.0

8.0

0306090120150180210240270

KM from River Mouth

DO

(m

g/l)

17/03/2007 12:00:00

18/03/2007 12:00:00

19/03/2007 12:00:00

20/03/2007 12:00:00

21/03/2007 12:00:00

22/03/2007 12:00:00

23/03/2007 12:00:00

DO in Chao Phraya River

0.0

2.0

4.0

6.0

8.0

0306090120150180210240270

KM from River Mouth

DO

(m

g/l)

24/03/2007 12:00:00

25/03/2007 12:00:00

26/03/2007 12:00:00

27/03/2007 12:00:00

28/03/2007 12:00:00

29/03/2007 12:00:00

30/03/2007 12:00:00

Water Quality Simulation Results

WQ Modelingwem.ait

Assignment

Improve the model calibration

Carry out a Sensitivity Analysis

Discuss!

Good luck!Good luck!

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Water Quality Model

Integrating Advection-Dispersion equation with expressions of WQ interactions

Solved by third-order finite difference scheme, QUICKEST

Composed of Decay of coliform

Oxygen interactions

Nutrients interactions

Advection-Dispersion Equation

SFhcy

chD

yx

chD

xvhc

yuhc

xhc

t yx

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Water Quality Relationships

FdFF CKt

C

Coliform Bacteria (Total and Fecal coliform);

First order decay

Depend on light, temperature and salinity

First order decay for BOD (dissolved, suspended, and settling organic matter)

Oxygen processes; photosynthesis, respiration, sediment oxygen demand and BOD decay

BOD-DO;