An auger hole test is performed on an unconfined aquifer with a saturated thickness of 20 m. The auger hole penetrated the first 10 m of the saturated aquifer and is 40 cm in diameter. The rate of water level change was measured when the water in the auger hole was 5 meters below the water table, and was determined to be 5 cm/s. Determine the hydraulic conductivity of the aquifer in the vicinity of the auger hole.