Groundwater patterns in a Playa Lake Basin, California; Analogue studies for geological disposal

Gallardo, A.*; Savage, D.*; Benbow, S.*; Takase, Hiroyasu*; Oda, Chie  

A numerical model was constructed to understand the groundwater flow dynamics and salinity distribution in the Searles Lake, California, a dry and alkaline playa lake, as a natural analogue for processes in a potential geological repository. The result shows that vertical flow would prevail at the center of the lake, and under this condition, salts would be dissolved from shallow evaporitic horizons being redistributed downwards and away from the lake surface. Concentrations up to 220 g/L would occur within an area approximately 6 by 4 km, extending to a depth of 200 m after 200,000 years. Although several uncertainties remain, the model is consistent with many observations, and provides a framework to address geochemical processes in the basin.