Monitoring of land subsidence due to excessive groundwater extraction using small baseline subset technique in Konya, Turkey

Konya, which is located within the Konya Closed Basin, is the most important agricultural production region in Turkey. The future of agriculture is threatened in this region due to the decline in groundwater levels and the intensive agricultural activities that require high water consumption and are not suitable to the climate conditions of the region. In addition to these parameters, the geological structure of Konya also poses various environmental problems such as land subsidence and sinkhole formation. This study aimed to investigate the causes of the land subsidence problem in Konya and its surroundings with the help of the interferometric synthetic aperture radar (InSAR) technique and auxiliary data, namely optic, Coordination of Information on the Environment (CORINE), and groundwater monitoring station data. In order to investigate the land subsidence in the study area, 58 Sentinel-1A images acquired between 2014 and 2018 were processed by using the small baseline subset (SBAS) technique. In addition, the time series derived from the SAR data was validated by a global navigation satellite system (GNSS) station located in the study area. The results revealed that severe land subsidence, some of which reached 75 mm/year, occurred in certain areas of the study area over a period of three and a half years. High consistency was found between the land subsidence and the groundwater level change observed in the region, with a cross-correlation of over 95%. Moreover, the temporal and spatial patterns of the cultivated area and urbanization, which are the main reasons for the consumption of groundwater in the region, were revealed using the optic data.

Automated summary

Konya, located in the Konya Closed Basin, is the most important agricultural production region in Turkey, but faces threats to agriculture due to declining groundwater levels and unsuitable agricultural activities for the climate conditions. Through the use of InSAR technique and auxiliary data, the causes of land subsidence in the region were investigated, revealing a strong correlation between land subsidence and groundwater level changes. Regional patterns of cultivated area and urbanization, major factors in groundwater consumption, were also identified through optic data analysis.