A study was conducted in Northern part of Atlantic Sahara coast (SW of Morocco) with the aim of assessing change of suspended sediment concentration (SSC) with time in sea surface from Landsat data with 30 m spatial resolution in order to understand the sand encroachment in the continental area. We must be report that is the first study of SSC monitoring in Southwest of Morocco using earth observation satellite (EOS). The methodology adopted in this research is simple and based on using band ratio (Green/Blue) for two images Landsat Thematic Mapper (TM) from the years 1987 and 2005. A step of classification was necessary, so unsupervised classification using K-means algorithm was applied on both band results from band ratio. After that, the statistical data result from classification was compared to determine the SSC and sand change with time. The results show that the sand increase in continental surface was in relationship with SSC decrease in coastal area. The SSC variation in surface sea indicates that sand input be decreased in next year's.