Change detection of coastal zone in Persian Gulf (1970 to 2002): Using topography map and remotely sensed data Saied Pirasteh Remote Sensing&GIS, Faculty of Engineering, Islamic Azad University of Dezful, Dezful (Iran) E mail:- moshaver1380@yahoo.co.uk Abstract: Persian Gulf is situated in the south of Iran and extends a kidney-shaped water body orientated in a northwest to southeast direction. The length of Persian Gulf is about 1000km. Shatul-Arab river from Iraq and the Karoon and Maroon rivers from Iran drain water with transportation material and further sedimented to Persian Gulf. It is caused in regression and transgression for changing the coast line from 1970 to 2002. In this research satellite TM data dated 1990 and 1993 with ETM satellite data of 2002 were compared in order to deduce changes. The result was calibrated to the topography map dated 1970 and field observations. All the three satellite data are geocoded and further georeferenced with topography map. Different image processing techniques are carried out to enhance the changes from 1990-1993 to 2002. Band math, band ratio, supervised and unsupervised classification, post classification, band selection and masking are applied using ENVI software. The coast line of the Persian Gulf was also digitized on topography map using Arcview software. This study shows that band ratio of 3/7 and 5/7 increase the enhancement for interpretation of the changes. This study also shows that selecting bands from three different images with making FCC (4-3-2) can enhance the change detection providing various colors in the image. It is also reveals that the coast line of Persian Gulf at places is regretted about 200 meters to 1500metes since 1970 to1990 and further to 2002 transgression is seen to 800 meters. It is also seen that due to large transportation's materials and sedimentation from Karoon, Maroon and Shatul-Arab rivers regression is taken place. However, the study indicates that modern image processing techniques beside GIS technology can provide good information for the change detection and coastal zones study where may be used for any coastal management program. Introduction The Persian Gulf is quite shallow. The Persian Gulf is a kidney-shaped water body orientated in a north west to south east direction. It is approximately 917 km long with its greatest width being 338 km. The Shatt-al- Arab river, the Gulf's main source of fresh water, Karoon and Maroon river flow primarily from Iraq and Iran respectively into the northern end of the Gulf. The Tigris and Euphrates, two of the largest river systems in the Middle East, merge together to form the Shatt-al-Arab river shortly before it enters the Gulf. At its south east terminus, the Gulf is linked to the Gulf of Oman and eventually the Arabian Sea and Indian Ocean via the Strait of Hormuz. Figure 1, a mosaic of NOAA AVHRR scenes acquired on September 1 and 6, 1990, shows the Persian Gulf and surrounding landforms. A portion of the Landsat satellite data with path and row 164/039 is selected in different dates (1990, 1993, 2002). The topography map in scale 1:250000 dates 1970 of the same area is taken. The emphasis is given to enhance the changes in coastal line during 1970 to 2002. Transgression and regression are two phenomena's influence the Persian Gulf coast line. Sedimentation and erosion are also two geomorphic factors which help transgression and regression.  Figure 1.NOAA mosaic satellite image of Persian Gulf and Iran Study area The study area relates to a 4097 by 2388 pixel image ( Figure 2) dealing with a section of the Persian coast line situated cross line to Bandar Geneveh City ( Figure.2). The Figure 2, a ETM false color composite (FCC) 4,3,2 image taken on 1990, identifies the study area and certain geographic features ( Figure 7). The bay near towards Iran is depth while the other places of the coast toward the Oman with its greatest depths not exceeding 5m)(Ackleson et al., 1992). The study area is covered about 166km of Persian Gulf coast line in Iran. It is bounded by geography coordinate 352445.25 mE ( upper left) - 3348992.25 Nm and 445668.75 mE- 3279708.75mN ( lower right) on the image.  Figure 2. Study area ( Persian Gulf) South of Iran. Satellite ETM image dated 1990 FCC 432 Geology and Geomorphology The present structure of the Persian Gulf is results of subduction and tectonic activities at the time of uplifting in the Zagros belt (Figure 3) in Tertiary during first the orogen. The maximum depth in Persian Gulf is towards Iran. It is indicating that there is a numerous different tectonic history during the collision between Iranian and Arabian plates. The Zagros mountain range (ZMR) in southern Iran, located on the Iranian side of the Arabian Platform, are one branch of the Alpine-Himalayan orogenic belt. The stratigraphy and sedimentology of the Zagros Thrust and Fold belt have been described by Falcon (1974), Farhoudi (1978), Ali and Pirasteh ( 2004) and Pirasteh (2004).The Phanerozoic column is about 12000 m thick. Paleozoic sedimentation was mainly epicontinental; from Permian to Miocene time it consisted chiefly of carbonates. The Tethys Sea began to subducted under the Iranian Plate in the Late Cretaceous. Cessation (Wolf, 1959) or slowing of subduction resulted in carbonate sedimentation in Early Cenozoic time (Farhoudi, 1978) as well as the deposition of 400m evaporatic materials in the Miocene. Orogenic movements began in the Middle or upper Miocene when sedimentation became clastic. The opening of the Red Sea intensified folding and uplift, which are still going on.  Figure 3. Trend of the Zagros Belt ended in Hormoz strait Persian Gulf Geologically (Figure.4)the study area is comprises different lithounits. The age of the lithounits is from Triassic to Recent. Dashtak Formation ( Figure.5) is consists of dolomite, shale and anhydrite. Kangan Formation is consists of limestone and dolomite. Dalan Formation comprises anhydrite, dolomite and limestone. Furghun Formation is also comprises of sandstone and very less amount shales. The Khuff (Dalan Formation) is present only in the Zagros fold belt and does not extend to central or northern Iran. It is also fully marine and is not a sabkha sequence. The Dalan carbonates marked the beginning of marine sedimentation in the Zagros basin, which continued almost uninterruptedly into the Early Miocene. These carbonates contain fusulinids and corals and correspond to the Khuff Formation of the Persian Gulf area (National Iranian Oil Co., 1978; Kashfi, 1992).  Figure 4. The geological map of Persian Gulf  Figure 5. Stratigraphic column of the Persian Gulf in Triassic-Permian (After Kashefi, 1976) The Persian Gulf Permian basin was an elongate trough with the greatest subsidence occurring in the southeast; therefore, the thickest sediments accumulated near the Oman Mountains. However, as with many other lithostratigraphic units in the Middle East, poor correlations and confusing nomenclature are the rule rather than the exception. This problem is even worse for the Permian-Triassic rocks as the data base (particularly the subsurface data) is scattered and largely inaccessible. Consequently, some information regarding the Permian-Triassic reservoir rocks has been presented incorrectly in various parts of the Middle East. The structure of the Zagros Thrust and Fold Belt consists of numerous, mostly northwest trending synclines and Anticlines. Steep flanks on most individual structures face southwest (Falcon, 1969). Dextral displacements have been reported on faults parallel to the Main Zagros Thrust between 33 º -35 º N (Tchalenko and Braud, 1974) and on the Kazerun Fault (Falcon, 1974). The near-basement salt and Miocene salt play a major role in the morphology and structure of the Zagros Thrust and Fold Belt. Geomorphologically rivers of Iran, with its source in the Zagros Mountains are karoon,Maroon, Dez, Karkheh. The total length of Karoon is 725 km, and it is navigable between Shushtar and the point where it joins Shatt El Arab in Iraq. Karoon has important tributaries, among them are the Dez river, with the conflux at Shushtar, and Kerkeh river coming from the north, with the conflux further downstream at Ahwaz. Transportation materials from Karoon and Maroon, Karkheh and Dez rivers are deposited and caused changes in coast line. Sediment materials are observed in Persian Gulf coast line. The drainages in the study area are medium to coarse. The Figures below ( Figures 6,7 and 8) show the evolution of the geomorphic processes in Persian Gulf.  Figure 6. A. Beginnings of the darinage development, B. erosional remnant and sedimentation, C. showing the sea level in two dates Methodology and digital image processing For the study of change detection of the Persian Gulf coast line many fields observation beside remotely sensed data are done. Global positioning system (GPS) is used during the field visits to attempt the georeferencing coordinates and note the elevations. Topography map in scale 1:250000 dated 1970 is scanned ( Figure.7). The digital topography map is georeferenced using the ground control points taken by GPS. On screen digitization is applied to extract the coast line. Satellite data are provided by the Iranian space department. Landsat thematic mapper (TM ) data dated 1990 ( Figure 8) and 1993 are georeferenced using digital topography map. Landsat enhance thematic mapper (ETM+) data dated 2002 ( Figure 9) is also georefereced using TM data. Various digital images processing (DIP) is attempted to detect the changes in Persian Gulf coast line. The remote sensing softwares like ENVI , ER-Mapper are used for DIP on the images. Supervised (Maximum likelihood) and unsupervised classification ( Isodata) ( Figure 10) is carried out for images. Post classification is applied to images to enhance the change detection. Normolize differential vegetation index (NDVI) is also is carried out ( Figure 11). Enhancement and sharpen filtering is also done on the images to extract the coast line. Band ratio and band math techniques are carried out to produce various images. Different false color composite (FCC) images are also produced. In order to make FCC images, band 4 ( red) from ETm 2002 and band 3 (green) from TM-1993 image and band 2 (blue) from satellite data 1990 are chosen. In other words, FCC images (RGB) red, green and blue is chosen for different bands and different dated images. The FCC processing results a new image with condition that lead us to interpret the change in coastal line of Persian Gulf during 1990 to 2002. The new FCC images are interpreted as follows:
For example band 4 is taken for making FCC from images dated 1990, 1993 and 2002 or band 4 and band 3 are taken as red and green and NDVI image as blue. This is result very clear image for increasing ability to digitize the coast line. Masking techniques are used to mask the unnecessary objects on the images. Raster images are converted to vector in shape file that use in GIS environment ( Arcview software) to making topology and generate maps. Later the results from the images are superimposed on digital topography map in scale 1:250000. The spatial analysis in GIS environment is made it easy to extract the different distance between coast lines produced by DIP on satellite images and digital topography map. All images produced by DIP techniques are compared to detect the coast line in different dates. The coast line is also digitally drawn on images using on screen techniques and compared to digital topography map. Therefore, the coast line is extracted from various images (dated 1990, 1993 and 2002) and digital topography map dated 1970.  Figure 7. Topography map in scale 1:250,000  Figure 8.Satellite image date 1990 showing Persian Gulf  Figure 9. Satellite image date 2002 showing Persian Gulf  Figure 10. Showing image produced using unsupervised classification (Isodata)  Figure 11 . Showing coast line using NDVI Results and discussions Remotely sensed data beside GIS techniques are increasingly used in earth sciences. This study discusses the role of remote sensing and GIS to make a proper management for coastal programming. Erosion and sedimentation are factors for changing the coastal line. Geology and geomorphology are also parameters to help changes during the time. The area probably is affected by the Gulf war during 1990 and sedimentation took place to help the changes in Persian Gulf coast line and environment. Different maps are produced in GIS environment and could be used in planning and port programming. This study shows that the band ratio 3/7 and 5/7 are increasing the interpretation ability to change detection of Persian coast line. It is also reveals that the coast line of Persian Gulf at places is regretted about 200 meters to 1500 metes since 1970 to1990 and further to 2002 transgression is seen to 800 meters (Figure 12). It is also seen that due to large transportation's materials and sedimentation from Karoon, Maroon and Shatul-Arab rivers regression is taken place. However, the study indicates that modern image processing techniques can provide good information for the change detection and coastal zones study where may be used for any coastal management program. Broadly the study emphasis on following objectives:
 Figure 12. Changes in Persian Gulf coast line Acknowledgement Author is thankful to Mrs. Leila Farzinpor for her kind support during the work. Author is also grateful to Iranian survey organization for providing topography maps. References
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