Water turbidity, transparency and colour
Component
Summary
Grade
Very poor Poor Good Very good
Confidence
In Grade In Trend
Comparability
To previous years

Water turbidity, transparency and colour

Relatively limited areas of naturally high turbidity are found in open-water regions

Year(s): 
2016
3
Stable
Confidence (in grade): 
Adequate
Confidence (in trend): 
Adequate
Comparability (to previous reports): 
Somewhat comparable

Water turbidity, transparency and colour

20162011
Marine environment
State and trends

Approach/Process

Satellite-detected ocean colour data can be converted to a range of estimates of water transparency. This conversion followed the method developed by Morel et al., 2007. SD depth is computed from the corresponding merged CHL1 products (weighted method), using the following empirical equation: SD depth = 8.5 − 12.6y + 7.36y 2 − 1.43y 3 with y = log10(CHL1). The detection of trends should be robust to the rapid rate of technological improvements to sensors, improvements in spatial resolution and improvements in validation. The global use of these data and the ongoing technological improvements will make the approach used here better in the future.

The measurement of water transparency using Secchi disk depth has a very long history, is widely used across the planet and is very inexpensive (Tyler, 1968).

The combination of remote sensing and direct observations provides a powerful tool for the assessment environmental condition and status.

Average from about 2008 to 2014 (= state) and simple linear regressions fit to seasonally detrended in situ Secchi disk data from each NRS (= trend). Regional scale (10°S to 45°S and 105°E to 160°E) average for December 2015 (=state) and simple linear regression from 1997 to 2015 for December regional average (= trend).

Further information on the assessment process can be accessed through the Australian Ocean Data Network SoE Metadata catalogue at http://catalogue.aodn.org.au/geonetwork/srv/eng/metadata.show?uuid=67f99849-4bdc-4531-a69b-2022e9d03fb8.

Tyler, 1968

Tyler JE (1968). The Secchi disk. Limnology and Oceanography, 1-6.

Morel et al., 2007

Morel A, Huot Y, Gentili B, Werdell PJ, Hooker SB & Franz BA (2007). Examining the consistency of products derived from various ocean color sensors in open ocean (Case 1) waters in the perspective of a multi-sensor approach. Remote Sensing of Environment, 69-88.

Comments

Nil.

Substantial changes to inshore water conditions and processes in the south-east

Year(s): 
2011
4
Stable
Confidence (in grade): 
Limited
Confidence (in trend): 
Limited
Comparability (to previous reports): 
Not assessed
Evans K, Bax NJ, Smith DC (2016). Marine environment: Water turbidity, transparency and colour . In: Australia state of the environment 2016, Australian Government Department of the Environment and Energy, Canberra, https://soe.environment.gov.au/assessment-summary-component/marine-environment/water-turbidity-transparency-and-colour, DOI 10.4226/94/58b657ea7c296