USING GIS-BASED ESTIMATES OF PALEOVOLUME: IMPLICATIONS FOR MONO LAKE DEGLACIAL HYDROCLIMATE

Significant geomorphic, chronologic, and stratigraphic data has demonstrated the western US Great Basin has experienced large hydrologic changes synchronous with abrupt climatic events during the deglacial period. Present chronologies of these changes have focused on large pluvial lakes (e.g., Bonneville, Lahontan, and Mono) within the context of lake level elevation, i.e., meters above sea level. However, assuming precipitation-evaporation is the dominant control on lake level changes, a more appropriate perspective may be through lake volume for the following reasons: 1) due to the intrinsic link between lake volume and basin geometry and 2) the extrinsic influence of basin geometry on evaporation potential. Volumes were calculated using a GIS approach from Mono Basin Digital Elevation Models at 1 m vertical resolution from the basin floor to the highest deglacial lake terrace.

The contrast in magnitude between the estimates of lake elevation and volume changes can be demonstrated from Mono Lake, CA. Mono Lake’s LGM lowstand to deglacial highstand fluctuation was an~190% rise in elevation(relative to its LGM lowstand). On the other hand, the volumetric increase was ~650%. Furthermore, this deglacial high was followed by a dramatic drop in lake level (~50% in elevation and ~250% in volume) at ~14.6 ka. Although using elevation to scale lake level changes is simple and straightforward to understand, critical climatic information may be lost by not considering volume. We are working to quantify the volume changes during significant climate events in order to better interpret the implied hydrological changes.