Hi Kouadri, I would recommend the free and open-source software "R"; however, if you do not know or have the time to learn the R programming language I would suggest MATLAB®. There are some scripts that can be found for MATLAB, which might be a better way forward. Might I also suggest giving the following paper a read, which used SOM for a landscape (watershed)-aquatic ecological analysis: Technical Report The Development and Evaluation of Methods for Quantifying Ri...