Spatio-temporal variations in characteristics of terrestrial water storage and associated drought over different geographic regions of Türkiye

Terrestrial Water Storage (TWS) is a critical hydrological parameter, the spatio- temporal variations of which have provided unprecedented opportunities for studies on Earth’s climatic system. Regional climatic characteristics bring about differences in the variation patterns of TWS. The evaluation and monitoring of TWS over regional to global scales is challenging due to the data paucity. The Gravity Recovery And Climate Experiment (GRACE) satellite mission paved the way for accurate large-scale surveillance of TWS changes. In this study, the monthly observations of the GRACE/GRACE-FO and hydroclimatic models were applied to evaluate the variations in the spatio-temporal characteristics of TWS. The associations between drought and the variations of water storage over the study area were also investigated based on the scPDSI and the GRACE-derived Water Storage Deficit (WSD) indices. According to the results, TWS has been decreasing over all the geographic regions of Türkiye suggesting a critical situation for the country from 2003 to 2020. The findings also showed that the GRACE-derived TWS performed well across Türkiye, with a significant correlation ranging from 0.86 (for the Mediterranean region) to 0.97 (for the Eastern Anatolian region) with GLDAS-derived TWS. It is also discovered that the monthly WSD time series correlated well with the scPDSI, with correlations ranging from 0.46 (for the Central Anatolian region) to 0.78 (for the Eastern Anatolian region). The analysis of the contribution of some effective hydroclimatic variables to the variations of TWS suggested that precipitation and soil moisture were the most dominant parameters affecting the TWS variability over Türkiye.