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IN LANDSAT TM IMAGES AND THEIR STATISTICAL RELATIONSHIPS Yusuf Kurucu, Unal Altınbaş, Mustafa Bolca, Burcin Cokuysal, Sezai Delibacak Agricultural Faculty of Ege University, Soil Science Department, Bornova, 35100, Izmir-Turkey ABSTRACT Objects on the Earth reflect the sun lights in different intensity and wavelengths. This is the base of remote sensing techniques, which is intensively use in many fields at the last quarter of the 20-century. In that context, borders of saline soils in Great Meander Basin, were determined by taking consider into reflection values of 7 3 2 bands of Landsat 5 TM satellite. According to results of land observations and laboratory analyses that saline soils were classified as Typic Halaquept. Typic Halaquepts were located on over flow mantle land physiography in valley landscape type. Since, poor drainage condition and high evaporation range intensive salt accumulation causes, especially in surface soils. They are usually used as nature land and land use capability classes of the soils are VIsw and VIIsw. The arithmetic mean, median, mode, minimum and maximum values of reflection values of saline soil from each band were determined, in addition variance for all parameter was calculated. Statistical relationships of reflection values from different bands were determined according to correlation and regression analyses procedures by computer. INTRODUCTION The remote sensing technique has been using for many of agricultural aims such as soil study, land cover and soil map. Use of remote sensing technique obtains some important advantages on mapping of some soil properties, espatially if the soils has poor drainage condition, saline or alkaline properties, texture differences etc. The Great Meander Basin has a very large delta, which were formed by various types of soils. Most of them are saline and have poor drainage condition. Decision-makers need to know detail of soil properties of the region and their boundaries to create a well design land use plan. Soils and other objects of The Earth reflect or absorb the sunlight. The reflected electromagnetic energy can be visible and invisible such as infrared and thermal wavelength. Sensors of the satellites can record separately both type of electromagnetic energy and they can be monitoring by the computer facilities. There are several results of the salt accumulation in the soils, such as rising up salty ground water by capillarite in soils and, irrigating by salty water. Salt can also be carried from sea through the lands, by waves, aquifers and winds. Evapotranspiration is also a reson of salt accumulation around the lake and lagoonary systems of the sea. The research area formed by accumulation of deposits, which were carried by Great Meander River through the Aegean Sea. Salinity problem has been detected in the soils which covers 1.7% (1.518.746ha) of Turkey and 3.8% (837.405 ha) of agricultural land of Turkey. Surface of the saline soils of the research area is 50.696ha (4). It is known that during the summer time, seawater moved through the land by aquifers. Satellite images were taken from Landsat 5 TM and 732 of band combination were used to delineate the distribution of the saline soil for this research. It is shown that, drawing the boundary of saline soils is easy and takes less time by use of Remote sensing technique, comparing with the conventional methods. MATERIALS and METHODS The research area were located on The West part of The Turkey and 100 km South of the Izmir. Main landscape type of the area is a valley. Saline soils were located on mostly delta and some of depression relief type of the valley. Satellites are permanent data source for land information, such as land cover and soil types, and they offer unique futures in the field . Landsat 7 TM images were used for the project. Their ground resolution is 30mx30m. TM is a scanning optical mechanic sensor system that records reflected and emitted energy in visible, reflective infrared , middle infrared , far and thermal infrared portions of the electromagnetic spectrum. The images are performed 7 spectral bands, which cover 0.45-0.52mm (1. blue) , 0.52-0.60mm (2.green), 0.63-0.69mm (3. red), 0.76-0.90mm (4. near infrared), 1.55-1.75mm (5. middle infrared , 2.08- 2.35mm (7. far infrared), 10.4-12.50mm (6. thermal). Saline soils were recognised by combination of 7.3.2 bands. Research were done in three stage, first, processing the images, second, gathering data from field work, soil sampling and analysing in laboratory and last stage for again image processing for drawing final maps. In firs stage, some band combinations were tested to find best combination and band combination of 732 was found as best combination to use for this research. Image was enhanced and geometrically corrected before unsupervised classified. According to results of unsupervised classification of the image , we had 7 soil groups in draft soil map of the research area. In second stage, soil groups were visited and 5 soil profile were dug and 35 soil samples were picked from each horizon to laboratory analyse. Besides total salt (soluble) contents of soils, the soils samples were analysed for measuring of organic mater, pH, texture cation exchange capacity and exchangeable cations. Data about general attributes of soil and environment were gathered during the fieldwork. In the last stage, satellite image was reclassified according to rules of supervised classification method . In this process, field observations and laboratory analyses were taken consider into and final map were completed. DISCUSSION Saline soils were recognised in two different types of relief in valley landscape system. Mostly, they were located on delta relief which near the Aegean Sea. They have usually dry surface soil, although their deep soils are moist or almost wet and they were covered by thin salt crust (Figure 1). Because of salt crust, the soils can be distinguished with very high pixel values and light colour in satellite images.  The other relief type of the saline soils were located in basin. During the alluvial plain formation, slightly higher lands ,with medium or coarse soil texture such as terraces, over flow mantle and levee relief types, and lower lands with fine and medium soil texture such as basin or depression relief types were formed. Main problem of the alluvial plain is poor drainage condition. Ground water table is very close the surface in lower lands. Quality of the ground water is not available to use for irrigation because of high content of salt. The soils which are located in the Basin relief type of valley have been affected by salty ground water. They usually have medium or high amount of clay in their soil texture, because of that , their moisture content is higher than that the other soils which located in higher lands and they don't have salt crust. On the contrary of the salt crust covered soils, the moist soils can be distinguish with lowest reflection values and dark colour in satellite images (Figure 2).  Fifteen test areas were determined for each soil units to measure reflection values of them. At least 10.000 pixels for each test area were studied and their statistical analyses were done (Table 1). According to the results, the highest reflection values in three bands were observed on salt crust covered area in delta relief, Although have high salt contents, the lowest reflection values were observed in basin relief, because basins have the most moist soil of research area. It is known that , moist soils can absorb the most of the sun light.  The other soils were observed with the reflection values in between delta and basin relief (Figure 3). Cation exchange capacities of soil samples were carried out between 7.34 and 25.68 me/100g. Exchangeable cations were determined as; Na+ 0.16-9.37 me/100 g; K+ 0.07-1.51 me/100 g; Ca+++Mg++ 6.20-17.75 me/100g. According to the results of laboratory analyses, Ca+++Mg++ and Na+ were found out as dominant cations in the soil samples. Exchangeable anions of soil sample were determined in saturation extract. According to results of laboratory analyses, exchangeable anions were found out as; Cl¯ 14.96-1440.66 me/lt; HCO3¯ 2.50-15.00 me/lt; SO4= 2.75 -231.89 me/lt. Reaction (pH) of the soil samples were measured in between 7.50 and 8.11.  REFERENCES Altınbaş Ü., Türk N., Seçmen Ö., Kurucu Y., Bolca M., Cokuysal B., Deibacak S. , Turk T. (1999). Reseaches on land use and soil taxonomic units of The west part of Great Meander Basin in Aegean Region by Remote sensing technique. 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Bestimmung von gesamt Humus und alkalischen Humusstoffen in Boden. Weinheim. U.S. Salinity Lab. Staff, (1954). Diagnosis and Improvement of Saline and Alkaline Soils. U.S. Government Handbook No:60, Printing Office, Washington. Zinck J. A. (1988). Physiography and Soil. International Institute for Aerospace Survey and Earth Sciences, Enschede, The Netherlands. |