Evaluation of GIS-based spatial interpolation methods for groundwater level: a case study of Türkiye

Groundwater is a valuable and universally distributed resource on Earth. Understanding the spatial and temporal dynamics of groundwater is of utmost importance for effective management. Normally, groundwater levels are recorded at arbitrary points, but groundwater modeling requires interpolating the measured values at specific grid nodes. This study aims to dentify and evaluate the geographical variations of groundwater levels in T & uuml;rkiye using three geostatistical interpolation techniques. Data from 355 groundwater wells from 1970 to 2019 were used for this purpose. In addition, an investigation of changes in annual average temperature and precipitation was conducted for two different time periods: 1985-2000 and 2001-2016. The results show an increase in the annual average temperature in T & uuml;rkiye by 0.82 degrees C during the reference period (1985-2000). Despite regional differences in the precipitation regime, the average annual precipitation in T & uuml;rkiye has not changed significantly overall. Especially in the Meri & ccedil;-Ergene, Konya Closed (Konya Kapal & imath;), and Euphrates-Tigris basins, a significant decrease in groundwater levels was observed, even though this decrease is less than 100 m in some wells. After a comprehensive analysis of all these data, possible explanations for the changes in groundwater levels were considered.