Prediction of water-level variations using a combined time series-geostatistical model in an aquifer surrounded by karstic formation: A case study from the semi-arid Hamadan province, Iran

Abstract Understanding groundwater responses to recharge is particularly important in alluvial aquifers which are surrounded by karstic formations in semi-arid and arid regions, such as the high Zagros region of western Iran. Evaluation of input and output time series provides comprehensive information on the hydrodynamic behavior of these aquifers. Time-series models were used to predict water levels using 20 years of monthly data (1997–2017) from 29 observation wells in the Nahavand Plain aquifer. Water levels were interpolated using conventional kriging and inverse-distance weighting and show consistent trends. Water-level change maps were prepared for annual intervals from 2012 to 2019 and for the period 2018–2022. Most of the area shows a trend of rising water levels, which appears to reflect recharge through karstic formations in the area.