The performance of irrigation systems can be evaluated by criteria which show the efficient use of on-farm water distribution. The different distribution of infiltration depths in the soil may give the same value of application uniformity coefficient; therefore the present study considered the distribution uniformity coefficient of the useful infiltration depths in the root zone as part of the evaluation criteria. The considered criteria was expressed as a function of both application adequacy and the application uniformity of infiltration depths. The derived function is applicable for linear and natural distribution of infiltration depths.