Asymptotic solutions to the convection-dispersion equation and Powell's optimization method for evaluating groundwater velocity and dispersion coefficients from observed data of single dilution tests

摘要: Abstract Groundwater velocity and hydrodynamic dispersion coefficients can be determined simultaneously from observed data of solute concentration at the center a single borehole. Two types asymptotic analytical solutions to convection-dispersion equation were proved applicable analyse borehole dilution tests. In order calculate groundwater velocity, longitudinal transverse as three unknown variables in solutions, Powell's optimization method was applied several cases together with Fletcher Powell. The results application these two methods assumed sets one actual experimental set tracer concentrations showed that based upon conjugate direction procedure without calculating derivatives is more reliable, flexible much faster converging true values than Fletcher-Powell, which on gradient utilizing both criterion functions their first derivatives. Furthermore, when proposed solution measured field, obtained quite reasonable.