Breakout session quick assment tool for under water light

1. 9 november 2015
Web application for simulation of
Secchi depth and Kpar UITZICHT
DSD 2015
Pascal Boderie

2. 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
9 november 2015

3. 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)
9 november 2015

4. Ecological key factors 2 - Light
9 november 2015

5. Institute
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. 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

8. Publication of Buiteveld (1995)
9 november 2015

9. Institute for Environmental
Reference books

10. 9 november 2015
Uitzicht publication (Buiteveld, 1995)

11. 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
9 november 2015