Land deformation and sinkhole occurrence in response to the fluctuations of groundwater storage: an integrated assessment of GRACE gravity measurements, ICESat/ICESat-2 altimetry data, and hydrologic models

Abstract

Uncontrolled extraction of water from groundwater aquifers causes groundwater depletion, which in turn triggers the formation of sinkholes in many parts of the world. Monitoring and detection of these geomorphologic features are of utmost importance and priority for the decision-makers to minimize significant environmental as well as socio-economic implications of land deformation. In this study, a systematic approach is proposed to investigate the spatio-temporal associations of groundwater storage changes with sinkhole evolution and land deformation by using a number of remotely sensed and modeled data as well as in-situ observations. The proposed approach is implemented and tested in Konya Closed Basin (KCB), Turkey, which is one of the most critical areas in central Turkey concerning sinkhole formation. The results of GRACE (Gravity Recovery and Climate Experiment) estimates suggest that there is a descending trend in the temporal variations of TWSA (Terrestrial Water Storage Anomalies) and GWSA (Groundwater Storage Anomalies) over KCB with an average storage depletion of 4.12 +/- 0.34 cm/yr and 3.40 +/- 0.61 cm/yr, respectively. The analysis of land deformation from ICESat/ICESat-2 (Ice, Cloud, and Land Elevation Satellite) altimetry data also indicates a descending trend with an estimated average vertical displacement of 5 cm/yr for the study area, which seems to be in rational accord with the sinkhole evolution over KCB. The results further suggest that the sinkhole evolution over KCB has an acceptable association with the variations of groundwater storage, groundwater use, and precipitation. Compared with previous works implemented over KCB, the findings of this study manifest a good performance for the proposed methodology. The integrated analysis of GRACE gravity measures, ICESat/ICESat-2 altimetry data, modeled groundwater abstraction, and in-situ observations of precipitation yields acceptable results for the detection and monitoring of sinkhole events provided that appropriate distribution of the elevation points from ICESat/ICESat-2 is accessible for the given study area.