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Keywords:

  • Salt Lake, Turkey;
  • remote sensing;
  • Landsat;
  • field spectroradiometer;
  • radiometric correction

Abstract

This paper focuses mainly on the investigation of water reserve changes in Salt Lake, Turkey, using remote-sensing data. The study is performed in two stages: (1) correlation analysis for real-time ground and satellite data and (2) assessment of water reserve changes using multi-temporal Landsat imagery. First, correlation analysis is conducted to investigate the relationship between digital data from Landsat-5 TM and spectral (in situ) measurements collected using a field spectroradiometer on the same day and time. A radiometric correction procedure, including conversions from digital numbers to radiance and from radiance to at-satellite reflectance, is executed to make satellite data comparable to in situ measurements. This procedure show that simultaneous ground and satellite remote-sensing data are highly correlated (0·84 > R2 > 97) and the near-infrared region (for this study TM4-Landsat-5 TM, band 4) is the best spectral range to distinguish salt and water on the satellite data for the multi-temporal analysis of the water reserve in Salt Lake. It also shows that the use of shortwave infrared band(s) will result in confusion for the determination of the water reserve in this water-covered study area. In a second and last phase, the water reserve change in the lake is examined using multi-temporal Landsat imagery collected in 1990, 2001 and 2005. The remotely sensed, sampled and treated data show that the water reserve in the lake has decreased markedly between 1990 and 2005 due to drought and uncontrolled water usage. It is suggested that the use of water supplies around Salt Lake should be controlled and that the lake should regularly be monitored by up-to-date remote-sensing data (at least annually) for better management of water resources. Copyright © 2007 John Wiley & Sons, Ltd.