Fig. 7. A sequence of 0.1-yr time steps from the periodic infiltration model illustrates (A) disturbances to the isotopic profile during the wet season, Steps 1 through 2, and (B) the effects of drainage and evaporation during the dry season, Steps 3 through 9. The atmospheric conditions (h = 40% and ¹⁸O_a = –21) are the same as those for Fig. 3 and 5. The soil type is silty sand for Parts A and B. (C) the ¹⁸O profiles at Time Step 3 for the three soil types considered in this study. Water input (¹⁸O of –16.5) occurs such that annually all of the infiltration (50 mm) comes during the first 0.3-yr wet period and is followed by a 0.7-yr dry period.