US Geological Survey


Date of this Version



Limnology & Oceanography, 39(2), 1994, 356-364


US gov't work.


A physically based model of variations in δ18O and δ2H in Pyramid Lake is presented. For inputs, the model uses measurements of liquid water inflows and outflows and their associated isotopic compositions and a set of meteorological data (radiative fluxes, air temperature, relative humidity, and windspced). The model simulates change of lake volume, thermal and isotopic stratification, evaporation, and the isotopic composition of evaporation. A validation of the model for 1987-1989 and 1991 indicates that it can reproduce measured intra- and interannual variations of δ18O and δ2H. Three applications of the model demonstrate its ability to simulate longer term responses of δ18O to change in the hydrologic balance and hydrologic characteristics (opening and closing) of the lake.