30 november 2015

Web application for simulation of

Secchi depth and Kpar UITZICHT

DSD 2015

Pascal Boderie

Light under water

Importance of light and visibility (Secchi depth)

• ecology (primary production)

• photolysis – decay of pollutants by uv light

• water temperature – influx efficiency (ir) and visibility

• public

• Modelling light is quite complex

• many definitions - radiance (source) en irradiance (receiving)

• IOP en AOP

• Light reflection

• PAR (400-800 nm) not equal to human eye sensitivity

30 november 2015

Light under water

Inherent Optical Property – independent of the light field:

• Scatter coefficient, b

• Absorption coefficient, a

• Beam Attenuation, c ( sum van a’s en b’s)

Apparent Optical Properties – depending on

light field

• Secchi disk depth (SD, m)

• Irradiance attenuation coefficient (Kd, 1/m)

30 november 2015

Ecological key factors 2 - Light

30 november 2015

Institute for

Environmental Studies (IVM)

5 Helsinki

RS summer

school

Optical active water quality parameters

Chlorophyll Pigments (mg/m3) CHL

Total Suspended Matter (g/m3) TSM

Inorganic fraction of TSM (g/m3) ISM

Coloured Dissolved Organic Matter CDOM

Water plants (macrophytes) floating - submerged

Bottom (depth: m)

Secchi Depth (m) SD

6

*

*

*

C C

NAP NAP

y y

a a Chla

a a NAP

a a CDOM

*

/2

2 ( )sin( ) d

NAP NAP

b

b b NAP

b b b B

wavelength a*_H2O b*_H2O a*_CHL b*_CHL a*_NAP b*_NAP a*_CD

OM

413 0.01 0.007 0.023 0.005 0.035 0.43 1.28

442 0.01 0.005 0.025 0.005 0.026 0.41 0.98

490 0.02 0.003 0.015 0.018 0.017 0.38 0.64

510 0.03 0.003 0.012 0.019 0.014 0.37 0.54

560 0.07 0.002 0.006 0.024 0.011 0.35 0.34

617 0.28 0.001 0.006 0.018 0.008 0.32 0.2

665 0.4 0.001 0.011 0.008 0.006 0.31 0.13

681 0.43 0.001 0.009 0.013 0.007 0.3 0.12

708 0.71 0.001 0.002 0.033 0.005 0.29 0.09

PAR (400-700) 0.035 0.005 0.011 0.016 0.011 0.35 0.34

mm 1/m 1/m mg/m2 mg/m2 g/m2 g/m2 1/m

Absorption & scattering

B~0.03

Publication of Buiteveld (1995)

30 november 2015

Institute for Environmental Studies (IVM) 10 Helsinki RS summer school

Reference books

30 november 2015

Uitzicht publication (Buiteveld, 1995)

Technical aspects

• Original Delwaq FORTRAN code to Javascript

• HTML with style-sheet

• GUI in Javascript

• All code is readable (ascii files)

• Runs on any (?) browser (IE > 8)

• “Light” easy to share

• Works on tablet and mobile phone

web demo http://www.andriks.net/uitzicht/nl/uitzicht.html

30 november 2015