Evaporation and salt flux from Owens Lake, California

Owens Dry Lake is a hydrologically closed basin at the south end of the Owens Valley, Southeastern California. The lake was desiccated by the diversion of most of the lake tributaries in the early 1900's. Dust originating from salts and sediments being blown off Owens Dry Lake is one of the largest point sources of PM-10 dust pollution in the United States. One source of the salts available to wind erosion is evaporation of groundwater at the lake bed surface. Several methods were used to determine evaporative flux from the dry lakebed surface, including three direct flux measurements (mini-lysimeters, evaporation pans, and flume measurements) two micrometeorological techniques (Bowen ratio and eddy correlation) and one soil chemistry technique (chloride profiling method). During this study, measured evaporative flux from Owens Dry Lake Bed was small, less than one mm/day, from most of the dry portion of the lakebed. In contrast, regions with standing water or brine showed much higher evaporation rates. The salt crust, which covers a majority of the dry lakebed, limits evaporation. Evaporation measurements sites were chosen to represent the lakebed's two distinctive soil textural delineations (sand and clay) and to represent both deep and shallow depths to saturation. Sites were also chosen in the lake's remaining brine pool and in the Cottonwood Springs area to represent high discharge environments. The collected evaporation data were used to interpolate a lake-wide evaporative flux and salt flux.