| o 
er 
| e + + + 
| e + + + 
| 9 er * + 
| a] s.0:0 405« 0-222 (B4) 2 + 
| &| Corr coeff : 0:809 el 
| ~ "o 
| © Std error: 0:14 Metres e 
® o wm + 
e o 500 - 600 nm wave band £i 
o e * + 
oo = 
we! > 
| C x = 
| mr 
| eo vo 
| a ol © 
| e" ze 
vo oS 
c uL eO 
2 e 
e 
e n à. 4. 3 e À A A À i — 
0 0.2 04 06 0-8 10 1.2 e 3 6 9 12 15 18 
Secchi depth in metres Turbidity in arbitrary units 
(a) (b) 
| 
| 
¥ = - 0:626 
| D$. 455-05- 262.16 (SD) C 
| = Conductivity = 705006 - 438-686 (sd) 
| SE-66-:21 mg /I no 
18 a ro WON 
no zo S-E = 59-51 hmhos /cm 
ESI "d J 
8 ES 
$t s 
8 = 
^3 28 
om = 
«© co 
z8. za 
nS 2° 
28 Be se UU à 
90.40 0.50 0.60 0.70 0-80 0:90 970.20 0:40 0-60 0-80 1-00 1-20 
Secchi dept in metres Secchi depth in metres 
(c) (d) 
Fig.4. Effect of colour on secchi depth and backscattered 
energy. (a) Proportionate relationship between secchi 
depth and backscattered energy (b) Secchi depth and 
turbidity are not related (c) Secchi depth and total 
dissolved solids (imparting colour) are related, and 
(d) Secchi depth and specific conductance are related 
619