Planning the management and optimized consumption of groundwater resources is a critical infrastructural necessity, as these resources supply a significant portion of the country's drinking water. A key component of this planning is accurately calculating the water balance, which requires determining the aquifer's hydrodynamic parameters, including transmissivity (T) and hydraulic conductivity (K). This study calculated these parameters using step-drawdown pumping test data from a single-well system across various locations in the 411-square-kilometer Hashtgerd Plain aquifer (an unconfined aquifer) with AquiferWin32 software. The results indicate that transmissivity is distributed unevenly across the plain. The lowest transmissivity values were observed in the southern (Kourosh Town) and southwestern (Najmabad) sectors, while the highest values were associated with the Kordan alluvial fan and its downstream lands. Based on these findings, maximum transmissivity was estimated at 3,682 square meters per day, with an average of 440 square meters per day. Hydraulic conductivity was determined by integrating saturated thickness data from geoelectrical studies with the previously calculated transmissivity values. The final results showed that hydraulic conductivity ranges from a minimum of 0.2 meters per day in the southern regions to a maximum of 9.7 meters per day in the central aquifer.
