The main purpose of this paper is to investigate multitemporal land surface temperature (LST) changes by using satellite remote sensing data. The study included a real-time field work performed during the overpass of Landsat-5 satellite on 21/08/2011 over Salt Lake, Turkey. Normalized vegetation index (NDVI), vegetation condition index (VCI), and temperature vegetation index (TVX) were used for evaluating drought impact over the region between 1984 and 2011. In the image processing step, geometric and radiometric correction procedures were conducted to make satellite remote sensing data comparable with in situ measurements carried out using thermal infrared thermometer supported by hand-held GPS. The results showed that real-time ground and satellite remote sensing data were in good agreement with correlation coefficient (R 2) values of 0.90. The remotely sensed and treated satellite images and resulting thematic indices maps showed that dramatic land surface temperature changes occurred (about 2°C) in the Salt Lake Basin area during the 28-year period (1984–2011). Analysis of air temperature data also showed increases at a rate of 1.5–2°C during the same period. Intensification of irrigated agriculture particularly in the southern basin was also detected. The use of water supplies, especially groundwater, should be controlled considering particularly summer drought impacts on the basin.

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The Karapinar basin, located in the Central Anatolian part of Turkey, is subjected to land subsidence and sinkhole activity due to extensive groundwater withdrawal that began in the early 2000s. In this study, we use Interferometric Synthetic Aperture Radar (InSAR), Global Navigation Satellite System (GNSS), and groundwater level data to monitor and better understand the relations between groundwater extraction, land subsidence, and sinkhole formation in the Karapinar basin. The main observations used in the study are InSAR-derived subsidence velocity maps calculated from both Sentinel-1 (2014–2018) and COSMO-SkyMed (2016–2017) SAR data. Our analysis reveals broad areas of subsidence with rates exceeding 70 mm/yr. The InSAR-derived subsidence was compared with GNSS data acquired by a continuously operating GNSS station located in the study area, which show a similar rate of subsidence. The temporal characteristic of both InSAR and GNSS time series indicate a long-term subsidence signal superimposed by seasonal variability, which follows the overall groundwater level changes, with over 80% cross-correlation consistency. Our results also indicate that sinkhole activity is limited to slow subsidence areas, reflecting strong cohesion of near-surface rock layers that resist subsidence but yield to collapse in response to aquifer system deformation induced by groundwater extraction.

The main purpose of this paper is to investigate multi-temporal land surface temperature (LST) changes of Konya Closed Basin (KCB) in Turkey using remotely sensed data. KCB is located in the semi-arid central Anatolian region of Turkey and hosts many important wetland sites including Salt Lake. Six Landsat-5 TM images selected from the 1984-2011 period were used in the analysis. A real-time field work was performed during the overpass of Landsat-5 satellite on 21/08/2011 over Salt Lake to collect coordinated temperature measurements using a handheld GPS and thermal infrared thermometer. All satellite images were geometrically and radiometrically corrected to relate the image data with in-situ measurements. Thematic LST images were used to evaluate the conditions over the region between 1984 and 2011. The results show that real-time ground temperature and satellite remote sensing data were in good agreement with correlation coefficient (R2) values of 0.94. The remotely sensed and processed satellite images and resulting thematic indices maps show that dramatic land surface temperature changes occurred (about 2°C) in the KCB from 1984 to 2011. Analysis of climatic data supports this finding. Air temperatures and pan evaporation had significant upward trends from 1984 to 2011. Analysis conducted using both LST and climatic data prove that the basin has been experiencing drought in recent years. It is suggested that the use of water supplies, especially ground water should be controlled taking into account particularly summer drought impacts over the basin.

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