The objective of this paper is to predict the effect of changes in future climatic conditions on the distribution and movement of moisture in the unsaturated zone CUZ) at Yucca Mountain. Modeling is conducted using TOUGH2, a multiphase, integrated finite difference numerical model (Pruess, 1991) calibrated using available saturation, water potential and pneumatic data fiom six boreholes. Modeling results indicate that fUtute climatic conditions may increase lateral diversion above low

more »

... ty units of the Calico Hills nonwelded (CHn) hydrogeologic unit and decrease lateral diversion above the Paintbrush nonwelded (PTn) hydrogeologic unit. The existence of lateral diversion above the CHn hydrogeologic unit is important because additional water flux due to increased infiltration may not travel through altered zeolitic layers, therefore decreasing the potential of radionuclides released fiom the repository to be sorbed by these layers. Collection and analysis of additional geochemical data will decrease uncertainty in capability of the PTn and altered CHn hydrogeologic units to create ban-iers to verticaI flow, and therefore improve confidence in fi~ture climatic predictions.