| dc.description.abstract | The multilevel slug test (MLST) is an in-well technique in characterizing the vertical distribution of hydraulic conductivity K(z) in aquifer. In modeling MLST, the well screen is either simulated as a uniform-flux (UF) or a uniform head (UH) condition. This study investigates the impact of the skin effect, positive or negative, on the UH and UF models. The positive skin effect, as associated with a reduced hydraulic conductivity surrounding the well due to drilling mud invasion, is taken into account by making use of a skin factor, Sk. The negative skin effect, as associated with an increased hydraulic conductivity due to overdeveloping of the well, is modeled by using an effective well radius, re, which is greater than or equal to the well radius, rw. The UF and UH models are compared using different values of Sk and re for a variety of the partial penetration ratio of screen length to aquifer thickness, , the vertical anisotropy ratio of hydraulic conductivity, , and the aspect ratio of rw to the screen length, . It is found that (1)For positive skin, UH and UF models yield the same results for both high- and low-K conditions, (2)For negative skin (-3| en_US | |