Hell Dear,

It depends on the sensor type. For example, Landsat, Sentinel or others have different bands that are dedicated to green band (esp. for chlorophyll a and b).You need to read the characters of the sensor you are using.

Regards,

Hailu

Hi Hailu,

I know that landsat have different spectral band. Actually, I combined the 7 spectral band in one RGB composite file with arcGIS 10.3. And now I would like to know which combination RGB is the best to observe qualitatively sediments or chlorophyll in rivers.

Regards,

Loris

Hi Loris,

Any band except 1 (aerosol), 8 (pan) and 9 (cirrus) could be meaningful. I did kind of a similar work with landsat band reflectances s for water quality assessment (salinity) in Florida Bay. In my experience I have seen that these inter-dependencies (between landsat bands and water quality indicators) vary for different cases (both spatially and sometimes temporally as well). If you have some known measurements of Chlorophyll or SSC values at the same location you're studying, I would suggest to check the correlation of each bands reflectance with the historical/ measured values. You can do that using multiple regression or some other convenient statistical tools. This might give you a good understanding of the actual case, and also provide you with substantial scientific rationale of choosing a particular band(s).

I hope this helped a little bit. Best,

Fahad

Loris, USGS provides a 'Spectral Characteristics Viewer' in order to figure out which Landsat 8 (and others) bands are most suited for the desired research application. If I were you, I would start with this tool first. In addition, I've added some other relevant links.

• https://landsat.usgs.gov/spectral-characteristics-viewer
• https://www.researchgate.net/post/How_can_I_measure_a_chlorophyll-a_from_the_Landsat_imagery
• https://landsat.usgs.gov/what-are-best-spectral-bands-use-my-study
• http://ieeexplore.ieee.org/document/8023757/
• www.mdpi.com/1660-4601/12/9/10391/pdf

Many thanks for the tips !

Regards,

Loris

Try any band combination. But it should contains band 1 (blue)

Thanks for the answer samy

dear Loris,

• It is better for you to use the ENVI software and doing supervised classification with SAM method Spectral angle mapper to get exact classification for water then interpret the spectral reflectance curves for each class of water types and sediments . that is better than using FCC of Bands to check the classes visually.

We found Landsat band ratio Blue/Red band very close to in-situ values of chlorophyll concentration over a river surface.

Try image thresholding, especially with the use of the Normalizaed Difference Water Index (NDWI), and identify the range of identified or noticeable sediments. This is another dimesion but demands your consideration.

Cheers.

Dear you can use NIR and thermal bands of Landsat satellite series

My regards

Landsat TIR bands spatial resolution is too coarse for the lake application in most cases. Green, and Swir bands (including MNDWI index) could be useful for sediment estimation. Blue, and red bands could help for chlorophyll estimation, as Muhammad suggests.

As it is said before it depends on the satellite. Landsat 7 is different from Landsat 8, however that is not the issue. It is important to determine if these satellites cover the spectrum you are supposed to use in order to estimate chlorophyll-a for example. Sometime using multispectral technology is not sufficient you may have to use hyperspectral technology. Please check the following two different literature for estimating chlorophyll-a from two different technologies:

Article Sea water chlorophyll-a estimation using hyperspectral image...

Article Monitoring water quality in the coastal area of Tripoli (Leb...

Best wishes

The use of Linear Spectral Mixture Analysis (LSMA) can also give you good result as it uses a sub-pixel application to perform a soft classification that will give you deeper insight into your subject. However, detailed fieldwork will be expected. However, you can get this using IDrisi, Erdas, ENVI, etc.

This work could help: DOI: 10.9734/JGEESI/2017/35209

Dear you need first to decide which satellite you need then select your band

Regards

@Loris

People initially sensed their environment based on the detectors they were given. Now we have the capability to use new detectors.

Suppose we were critters starting out with these new detectors . ... How would the world look to us? The attached paper provides a way of answering that question, a way of seeing the world with new detectors. A robust formula for comparing the shapes of finitely sampled spectra is presented.

(To be clear, I am not talking about false color, but of a way of digesting the full spectrum of a target using many detectors.)

Choose the bands you want to by comparing the spectra to be observed by the detectors.

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You still have not said the satellite available to you. It will go a long way to thread our discourse on the subject.

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Regardless of the satellite, you need some knowledge about the parameter of interest to choose the best bands and/ or combination below several examples of the most commonly used parameters:

turbidity = NIR*red/ green

TDS= green

chlorophyll = blue/red