HIBAL: a hydrologic-isotopic-balance model for application to paleolake systems

A simple hydrologic-isotopic-balance (HIBAL) model for application to paleolake delta(18)O records is presented. Inputs to the model include discharge, on-lake precipitation, evaporation, and the delta(18)O values of these fluid fluxes. Monthly values of climatic parameters that govern the fractionation of O-18 and O-16 during evaporation have been extracted from historical data sets and held constant in the model. The ability of the model to simulate changes in the hydrologic balance and the delta(18)O evolution of the mixed layer has been demonstrated using measured data from Pyramid Lake, Nevada. Simulations of the response in delta(18)O to step- and periodic-function changes in fluid inputs indicate that the hydrologic balance and delta(18)O values lag climate change. Input of reconstructed river discharges and their delta(18)O values to Pyramid and Walker takes indicates that minima and maxima in simulated delta(18)O records correspond to minima and maxima in the reconstructed volume records and that the overall shape of the volume and delta(18)O records is similar. The model was also used in a simulation of abrupt oscillations in the delta(18)O values of paleo-Owens Lake, California. Published by Elsevier Science Ltd.