Overall it strongly depends on your research objective. For an instance, if you would like to investigate the diurnal dynamics of suspended particulate, you did not have many choices (just geostationary satellites). The effect of the difference particles in water column such as suspended inorganic and organic matter and etc. on electromagnetic radiations relates to the wavelength you considered. However l=650nm has been proved to have high sensitivity to suspended sediments and less sensitivity to chlorophyll and organic particles. Now you have a lot sensors (depending on your desired spatial/temporal resolution) to get suspended particulate (e.g. ASTER LANDSAT8 and so on). The main procedure is to use radiative transfer model to relate in situ measurements and at-satellite radiance measurements.

See this:

V. Volpe, S. Silvestri, M. Marani, Remote sensing retrieval of suspended sediment concentration in shallow waters, Remote Sensing of Environment, Volume 115, Issue 1, 17 January 2011, Pages 44-54, ISSN 0034-4257, http://dx.doi.org/10.1016/j.rse.2010.07.013.

(http://www.sciencedirect.com/science/article/pii/S0034425710002294)

Amir thanks did you tsted in Persian Gulf waters, yourself. I found that Nechad et al., 2010 approach worked well with MODIS.

It depends as well on the image processing software and , thus, of the available tools. When using ENVI software for processing LANDSAT data, I test first for the visualisation of marine currents the RGB band combinations 2,1,7 and then the Gaussian filter. Of course, seasonal effects have to be considered.

Thanks Barbara. What methodology you have used for seatruthing?

Both IRS-OCM and Sea-Wifs should solve your purpose.In my experience, spectroscopic approach is better than the band ratio based approaches. If sediment load is high,the NIR bands are more sensitive than the visible bands. One of my recently published paper,"Ramakrishnan, D.,Rishikesh Bharti, Das,M. (2013), A Technique for estimation of suspended sediment concentration in very high turbid coastal waters: An investigation from Gulf of Cambay, India. Marine Geology,346,256-261" should answer your questions in detail

Thanks Rama.

Dear Saif,

Look at the publications coming out of the Belcolour project in Belgium (http://www.mumm.ac.be/BELCOLOUR/EN/index.php). They came up with several novel approaches to estimate turbidty from space (including using geostationary satellites such as SEVIRI). Relation between turbidity and reflectance in not linear, and the nonlinearity shifts to the red and NIR with concentration (the nonlinearity is due to an approach to a constant value of reflectance with SPM dominates both absorption and scattering at a given wavelength, resulting in a near constant reflectance. The reason it still works further and further into the NIR is because water absorption is much stronger in that region and contributes to the signal when it may be negligible in the red.

Validation can be done with SPM samples as well as with proxies such as single wavelength optical attenuation and scattering (which is what turbidity meters measure). Good luck!

Thanks Emmanuel, will try to use it with the data I collected a while back. I have used the methodology proposed by Nechad et al., 2010.

Nechad, B., Ruddick, K.G., Park, Y., 2010. Calibration and validation of a generic multisensor algorithm for mapping of total suspended matter in turbid waters. Remote Sensing of Environment 114(4), 854–866.

Hello Everyone,

Good suggestions on how to detect, map, and monitor suspended sediments have been given and thought I'd add some of what I have done/seen in my work related to suspended sediments using remote sensing.

I have used remote sensing to investigate ways to detect and monitor suspended sediment information at several locations including San Francisco Bay (using Landsat TM images), coastal regions in Hawaii (using Landsat TM, aerial imaging, and field based digital camera systems), and the Colorado River at the bottom of the Grand Canyon (mounted a spectral radiometer with Landsat TM bands on the shore line and collected spectral measurements every 15 minutes for over a year). The correlation between the remotely sensed spectral information were correlated with field samples that were collected at various times during the life of the projects.

A couple of things that are important to keep in mind when investigating the use of spectral data to help monitor water surfaces are:

1. Sun glint and wave action can (and will) influence the spectral measurements that are collected for some of the pixels/areas being monitored. Depending on the sun elevation and view angle this can be a minor or major issue to deal with. The higher the spatial resolution the higher the influence will be on an individual pixel.

2. The correlation between the spectral measurements (and various ratios) can (and will) depend on the range of the concentration levels of the suspended sediments in the water. In the case of coastal waters often the concentration levels are relatively low to moderate. In this case the visible bands will be the most useful, however, when the concentration levels get high (as can on coastal waters during flood runoff or rivers during flooding --- as it did on the Colorado River in the Grand Canyon) the NIR band can become quite important.

The link below will show you an example of the use of Landsat TM in the San Francisco Bay and the attached file contains a graph that shows the relationship between the silts/clays and the ratio of the Nir2Red radiance values collected using a spectral radiometer with Landsat TM bands. Note that once the concentration levels get moderate to high the correlation with the ratio that includes the NIR band becomes high.

       http://water.usgs.gov/osw/techniques/workshop/chavez.html

Good luck with your research.

Pat

[RadiometerRadiance-Ratio-Nir2Red.jpg]

Chavez you are right. But didi you experiment with MODIS data? I see band ratios work quite reliably in areas where the SPM is around 10 - 30 mg/L

Secchi disk depth is estimated by

MODIS Kd490. Secchi disk depth is a criterion to estimate

water turbidity. To gain more information, you can refer to the following publications:

Conference Paper Developing satellite-based tool for water turbidity mapping ...

Article A novel method for characterizing harmful algal blooms in th...