Spatial estimation of aquifer’s hydraulic parameters by a combination of borehole data and inverse solution

A combination of borehole data interpretation and inverse solution method used to estimate the spatial distribution of hydraulic conductivity (K) and specific yield (Sy) for the Bandar-e Gaz unconfined aquifer located in Northern Iran considering no access to pumping test data. A numerical model used to simulate the behavior of the aquifer in two 12-month calibration and validation periods. The Nash-Sutcliffe criterion in calibration and validation periods indicates a completely appropriate accuracy and reliability of the combined method. The values of calibrated K and Sy by the inverse solution method are in accordance with their initial estimated values based on boreholes logs data. The estimated K and Sy are in the ranges of 5–15 and 0.024–0.036 m/day and their spatial distribution pattern shows a decreasing trend in the south-to-north direction, which is well suited to the spatial pattern of aquifer sediment’s type and size.