Hi,

I think that there is no general approach which could be applied. Of course, SAR intensity is influenced by soil moisture. But it is also influenced by roughness and shape of the surface. So according to my understanding at least two things are necessary for soil moisture mapping:

Multi-temporal data: You can not retrieve soil moisture by a single image. Variation in SAR backscatter over a longer time (at best between rainy and dry seasons) gives you the variation which can be expected.

Field data: There is no general mathematical relationship between SAR backscatter and soil moisture. It strongly depends on the properties of the ground, the climatic setting and the mode and resolution of the sensor. I would highly disadvise from adopting regressions from studies which claim to have found this relationship, because it is strongly limited on their geographical and temporal conditions. Only when you collect own measurements at your study sites you can correlate it to your SAR images.

There is a reason that operational soil moisture retrieval is currently limited to a resolution of 500 m or 1 km.

- The above originally taken from "http://forum.step.esa.int/t/soil-moisture-mapping-using-sentinel-1-data-and-snap/2027/2?u=abraun"

You can look at the following link it might be helpful:

rs.geo.tuwien.ac.at/share/publications/publ/0048.pdf

www.itc.nl/library/papers_2016/msc/wrem/cliu.pdf

www.mdpi.com/2072-4292/5/10/4961/pdf

Hi!

I agree with Sayan. Additionally, you can use NDVI or EVI (EVI is only included in the MODIS products -Aqua and Terra satellites-, but if you make use of the EVI-function it is possible to obtain the same result) to estimate soil moisture (with a delay of course...).

NDVI: https://en.wikipedia.org/wiki/Normalized_Difference_Vegetation_Index

EVI: https://en.wikipedia.org/wiki/Enhanced_vegetation_index

The following papers will give you an indication as to how this can be done:

source: https://www.researchgate.net/publication/220110070_Estimating_root_zone_soil_moisture_at_distant_sites_using_MODIS_NDVI_and_EVI_in_a_semi-arid_region_of_southwestern_USA

source: http://www.sciencedirect.com/science/article/pii/S0022169407002004

source: http://www.sciencedirect.com/science/article/pii/S1474706515000200

Hope this was useful!

Cheers,

Karolina

Article Estimating root zone soil moisture at distant sites using MO...

Hi Fereshte,

Number of different algorithms and  methods are available to estimate the soil moisture from the satellite images especially from RADAR data (SAR data).

Please see the attached document prepared by researchers from Monash University, Australia. They clearly explained all the methods and techniques to be used analyze the soil moisture from different RADAR data sets,

Hope this will help you to process your data.

Good luck

Truly

Vijith

Hi Vijith

thanks very much

but I need an article which is specifically related to SENTINEL 1.

would you please send me the articles which have to do with SENTINEL 1?

Hi Fereshte,

Please find the attached papers.

Hope this will help.

Truly

Vijith

How can I pre - process sentinel-1 image step by step in snap software?

 Hi Fereshteh,

I am doing some research about soil moisture estimation using sentinel-1 image, do you find some useful information?

eg. pre processing image step by step in SNAP? How to get backscattering coefficient from sentinel-1 image? 

Cause I find that this coefficient is related to soil moisture

Thanks for helping. 

I need your help

Hi Fereshteh

I am going to use sentinel 1 images for mapping soil moisture on an watershed. But i do not know its steps. Can you help me please?

Hello Fereshteh and Maryam,

I am a postgraduate student of national Taiwan university, and I am also using sentinel-1 images to estimate soil moisture, and I have done the processing of the images, the next step maybe establish the relationship between db and soil moisture. Maybe we can discuss some skills and experience of some information.

Here is my email address and my facebook account

[email protected]

Terry Chan

Hopefully we can discuss together in order to finish our researches.

Thanks 

I also need help to estimate soil moisture from Sentinel 1. I would like to discuss with you Kam Lon Chan. I'm trying to established a relationship between soil moisture and the data from Sentinel 1. What do you recommend to me?

سلام خانم قنبری.

تونستید نتیجه ای بگیرید. ممنون میشم اگه اطلاع بدید.

I am working on the soil moisture retrieval form the sentinel-1 data. Basic steps for data processing of sentinel-1 is known, but how to retrieve the soil moisture, Could you please help me?

You can use SNAP for preprocessing

see this

http://step.esa.int/main/doc/tutorials/sentinel-1-toolbox-tutorials/

Do you work to sentinel-1 images for retriveling the soil moisture Mr. Zohary?

I need help to estimate the soil moisture from sentinel 1

Kam Lon Chan . I am working on retrieval of soil surface moisture using Sentinel-1 data of entire India. I have sent an email to you regarding the same. We are also planning to use RADARSAT-2 or Alos PALSAR-2 dataset for this task along with UAV Hyperspectral data for validation.

I imagine you figured out how retrieve soil moisture by now, but anyway, the article "Synergistic Use of Sentinel-1 and Sentinel-2 Data for Soil Moisture Mapping at 100 m Resolution" might be help you.

also after Radar processing you can implement Tu Wien change detection method to retrieve soil moisture.

sentinel_1 GRDH processing procedure in SNAP:

-apply orbit file, - noise removal, -calibrate to Sigma0, - Multi-looking, -filtering, -range and Doppler train correction

cheers.

dear for your interest you can use different types of algorithm to do so, based on roughness

Regards

I am doing some research about soil moisture estimation using sentinel-1 image, I need image processing step by step in SNAP? How to get back-scattering coefficient from sentinel-1 image? I find that this coefficient is related to soil moisture.

it is possible to estimate the soil moisture at the base of the SENTINEL1 data, even if it contains only two VV and VH polarizations. Fereshteh Ghanbari

I am also doing a research about soil moisture estimation using sentinel 1. Can you please help me on how to retrieve soil moisture? It would be much appreciated

Sentinel `1 and 2 data use for soil Moisture estimation.

You can use SNAP for preprocessing

see this

http://step.esa.int/main/doc/tutorials/sentinel-1-toolbox-tutorials/

I need help to estimate the soil moisture from sentinel-1 , if possible some papers related to this case

Let’s say you start from Gamma naught-calibrated and projected S1 images (Gamma being corrected for topographic changes, i.e. local incidence angle variations. You probably don’t want to use Beta or Sigma). You need to understand what is impacting the strength of the backscattering signal. Two main parameters are important (this is a simplification): the dielectric properties of the surface, which includes moisture and salinity, and its structure (for a soil, the shape of the surface is defined by surface roughness – for which the estimation is a fractal problem, btw). You will need to dig into literature to find how researchers have been able to separate the unwanted components to better inform on moisture. In terms of change, can you assume surface roughness and salinity have been stable in time? Just some ideas to think about.

Hi Rida Khellouk Aysar Jameel Abdalkadhum Aubrey Menioria Narsimha Rao

Yes, you can estimate surface soil moisture with only VV and VH polarised Sentinel-1A data (Dual polarised data). Please go through the publication below

https://www.mdpi.com/2072-4292/12/14/2266/pdf

Rida Khellouk Ismail Mondal Abhilash Singh hi, I would like to ask. I’m having trouble in processing Sentinel 1a images in SNAP. I can’t even process the first step which is “apply orbit file”. Do you have any other solution?

Hi Bazilah Ho, you can follow this pdf.

https://www.mdpi.com/2504-3900/18/1/11/pdf ( Sentinel-1 GRD Preprocessing Workflow)

Inbox me if you face any problem related to the processing part.

Abhilash Singh thank you sir for the suggestion.

Short answer, yes. However, the approach I am familiar with is using Sentinel-1 data to invert a theoretical model called the Integral equation model to calculate SMC. The data in question are the backscattering coefficient in VV, VH polarisation (sigma) and incidence angle.

You can use this publication as an inspiration:

Article Potential of Sentinel-1 Images for Estimating the Soil Rough...

Hello Mr.Oualid, would you please send me the IEM code.

Here you go:

https://rscl-grss.org/coderecord.php?id=469

I am afraid, I could not find the Matlab version of it, you might have better luck.

Thanks for your response. is it possible to estimate soil moisture using as input :

Sigma0vv + sigma0vh + incidence angle ?

I do not have any roughness information and I tried to retrieve soil moisture based on sentinel 1 using snap but this solution requires mutli-polarisation image VV VH and HH or my images are dual vv and vh pol. Please any suggestions?

hello

maybe this paper will be useful

A Machine Learning-Based Approach for Surface Soil Moisture Estimations with Google Earth Engine

https://www.mdpi.com/2072-4292/13/11/2099

Hello José, I am very thankful for your reply.

From my personal experience, the surface roughness parameters are key for the IEM inversion. I was in a similar situation when I had no surface roughness measurements and the produced estimations were inaccurate, to say the least. But you can always try different approaches in literature as Jose suggested.

Semi empirical model such Dubois model, water cloud model etc., is available which u can try with ENVI software. Surface roughness measurement and estimating dielectric constant is prominent for soil moisture estimation.

Hello Mr. Thababalan thanks for your answer. Would you please let me know how to get the code of those models because I couldn't find its or they are implemented in envi software?

If ay only have as data Sigma0vv + sigma0vh + incidence angle is it possible to estimate soil roughness, dielectric constante , soil moisture? Any kind of steps to follow will be very helpful sir

Yes, The semi-empirical model such as modified dubois model having equation for sigma0hh and sigma0vv which is you can refer many papers, where surface roughness is given as input to retrieve dielectric constant and with dielectric constant as input can retrieve soil moisture which needs to be validate with field measurements.