The benefit of using data on canal seepage and tracer concentration in aquifer parameter estimation

We evaluate the benefit of using field data on groundwater fluxes to canals and pore-water solute concentrations, in addition to data on hydraulic head, to estimate model parameters for groundwater flow. The field site was a 100 km(2) area of the Biscayne Aquifer in southeast Florida. A total of seven models were calibrated to different combinations of 196 observations of groundwater head, 56 measurements of seepage between the aquifer and canals, and 196 measurements of pore-water chloride concentration. Each of the calibrated models was evaluated by testing its ability to predict the spatial and temporal variability in groundwater head and canal discharge during a 10 day canal drawdown experiment. The results of the simulations demonstrate that: (a) the models calibrated solely on hydraulic head measurements predict data on hydraulic heads and water fluxes poorly; (b) the models calibrated solely on seepage fluxes predict accurately, only if the number of parameters estimated in the calibration is restricted; and (c) the models calibrated on at least two types of data (e.g. hydraulic head and seepage fluxes) exhibit good predictive capability, regardless of the number of parameters estimated.