Salt classification and distance to shoreline using visible bands of Landsat, case study, Orumieh Lake, Iran

The salt concentration influences the vegetation tolerance and also agricultural crops. It is also important to detect sea level changes by climate and human activity. Salt increase may provide a potential origin for airborne dust hazards, as previously investigated by authors. The coastal land in the south of Orumieh Lake, as a part of the fluvial fan of the rivers going into the lake, was examined in this research to investigate the salt concentration distribution by distance to the shoreline, about 75 Km long, and by elevation. The research wants to test the hypothesis that whether the salt decrease with a distance to the shoreline or elevation. The salt concentration was classified in a combination image from 3 bands of Landsat ETM+, in the range from 0.4 μ to 0.7 μ, after the required correction was performed. Distance to the shoreline and DEM layers have been prepared by ArcGIS Spatial Analysis. The area by standard deviation method was classified in 5 categories of extremely salty, salty, moderately salty, less salty and non-salty areas. Each pixel value in the classification layer has a corresponding value in distance to shoreline and DEM layers. The extremely salty category has been revealed by a query to have the least average distance and it is stretched as a strip along the coast. The salty category does not have regular variations with the distance but it was more a function of the elevation changes and consequently the sea level changes. The category of moderately salty with the most area is located in the middle of the study area, from about 4 Km to about 12 Km from shoreline. It can be concluded that the 5 categories are arranged in order from the shoreline and that the more the proximity to the shoreline the more the salt concentration. The novel method also proved to be applicable to the analysis of relations between classification and distance and DEM layers. It can be concluded that the changes in level of the lakes can increase salt classes and consequently contribute to intensification of dust storms as hazard previously experienced in the west of Iran.

Keywords:

Salt Concentration , Classification , Landsat , Orumieh Lake