SJIF IMPACT FACTOR (2015): 5.42 CRDEEP Journals International Journal of Basic and Applied Sciences Abuelgasim & Ammad Vol. 6 No. 4 ISSN: 2277-1921 Online version available at: www.crdeepjournal.org/ijbas 145 International Journal of Basic and Applied Sciences. Vol. 6 No. 4. 2017. Pp. 145-150 ©Copyright by CRDEEP Journals. All Rights Reserved. Full length Research Paper Mapping Sabkha Land Surfaces in the United Arab Emirates (UAE) using LANDSAT 8 Oli Visible Data Abdelgadir Abuelgasim 1 and Rubab Ammad 2 1- Department of Geography and Urban Planning, College of Humanities and Social Sciences, United Arab Emirates University, Al-Ain, Abu Dhabi 15551, UAE. 2- Department of Biology, College of Science, United Arab Emirates University, Al-Ain, Abu Dhabi 15551, UAE. Introduction Sabkha are salt flats associated with hot and arid climate, typically formed in shallow continental shelf/ marine environment (G. Evans .1970; Kendall et. al. 1994). They are classified as inland sabkhas, present within the sand dunes, or coastal sabkhas, found on shoreline and distinguished based on formation in varying tidal environments; 1) sub-tidal flats, 2) lagoons and intertidal flats, 3) supratidal flats (Pain & Abdelfattah, 2015; Shinn, 1983). Inland sabkhas that form within the sand dune areas are relatively flat and highly saline areas of sand or silt formed just above the water-table where the sand is cemented together by evaporite salts from seasonal ponds. Coastal sabkhas are characterized by evaporite deposits, which may consist of carbonates or siliciclastic. The primary objective of this research study is to develop a new technique for mapping inland sabkha surfaces using multispectral remotely sensed data. Identifying sabkha pixels in remotely sensed images has been quite an arduous process (Allbed and Kumar 2013). This is primarily due to the confusion of sabkha pixels with saline soils and the mixture of sabkhas with sand dunes making spectral separation a challenging process (Ammad and Abuelgasim, 2016). This research uses the multispectral information provided by Landsat 8 data in addition to a set of transformed multispectral data including principal components and a sabkha to accurately identify sabkha pixels from other land cover pixel types. Materials and Methods Study Area The climate of the area is hot, dry and arid with scarce amount of annual rainfall around 72 mm (Raafat, 2007) and rates of evaporation exceeding 2000 mm per year (Paul, Al Tenaiji, & Braimah, 2016). This high evaporation rate accounts for salinities ranging from 37% near Strait of Hormuz and 65% in the Arabian coastal lagoons (Alsharhan & Kendall, 2003; Bathurst, 1975) whereas in shallow depths of UAE coastal areas the average salinities vary from 40-50% and in lagoons and embayments they can reach up to 60-70%(Evans, Schmidt, Bush, & Nelson, 1969). The temperature 25cm below the sabkha goes up to 17°C in winters and 43°C in summers respectively (Lokier, Knaf, & Kimiagar, 2013). The Shamal wind is the prominent climatic feature of the area, which blows in north- west direction. Storm outbreaks result in shallow inundation of the coastal area due to ramp geometry of coastline. Article history Received: 30-07-2017 Revised: 08-08-2017 Accepted: 14-08-2017 Corresponding Author: Abdelgadir Abuelgasim Department of Geography and Urban Planning, College of Humanities and Social Sciences, United Arab Emirates University, UAE. Abstract The UAE is home to some of the largest concentrations of sabkhas both coastal and inland. Sabkha is an Arabic word for a salt-flat area found mainly along arid area coastlines and inlands within sand dunes areas. Detecting and mapping sabkha land surfaces from satellite data is an arduous process. Most classification techniques of multispectral data alone, usually fail to properly identify sabkha pixels or provide lower rates of mapping accuracy for sabkha surfaces. The primary objective of this research is to develop a much more accurate methodology for properly mapping and identifying sabkha areas from remotely sensed data. Properly mapping sabkha surfaces from remotely sensed data is the first steps towards studying the ecological changes within such surfaces using earth observation techniques. Furthermore, sabkha surfaces can in certain situations be a geotechnical hazard due to its highly salinity and with adverse effects on concrete, asphalt, steel and other structures, in addition to their sporadic heaves and collapses. As the UAE continue to build major infrastructure and development projects identifying the location of such surfaces is vitally important. In this study, a sabkha index is developed based on the visible spectrum information provided by Landsat 8 OLI. The index was accurately able to identify sabkha polygons within the study area at an accuracy of 75% in comparison to other soil salinity indices using the same spectral information (62.5%). Key words: Sabkha, Soil Salinity, Landsat 8, UAE