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In Turkey, desertification has been taking place in areas of low rainfall and minimal vegetative cover. In particular, the central, eastern, and southeastern parts of the country are vulnerable to desertification because of erosion, deforestation, and degradation of vegetative cover. Rivers of those regions are characterized by very high sediment yields. Nearly 60% of the country’s soils are subjected to severe erosion and approximately 450 million tons of sediment are carried to rivers each year. Meanwhile, wind erosion has been a very effective desertification process in central and southeastern parts of the country, where annual rainfall varies around 400–500 mm/year. Most central and southeastern parts of Turkey are considered semiarid, and some parts of the Central Anatolia region around Tuz Lake exhibit arid conditions, with 300 mm/year rainfall.
This study presents a potential use of remote sensing for monitoring desertification with AVHRR-derived NDVI (Normalized Difference Vegetation Index) data. NOAA series operational meteorological satellites provide data that can be used for various earth observation applications, such as vegetation indexes, sea surface temperatures, hydrologic applications, and natural disasters. The Advanced Very High Resolution Radiometer (AVHHR) is a multichannel scanning radiometer carried by the NOAA Polar Orbiter satellite series. It is a 5-channel radiometer, using a spinning mirror to scan across 111 degrees for a ground swath of 2,700 km, with an IFOV at a nadir of 1.1 km. Because of the temporal characteristics of AVHHR, it is possible to obtain valuable information for vegetation monitoring studies and other environment-linked applications (Gutman, 1991).