Kostiakov Infiltration Parameters from Kinematic Wave Model

Abstract

The Kostiakov infiltration equation relates cumulative water infiltrated to the infiltration opportunity time. The kinematic wave model can be used to simulate surface irrigation system performance. Input to the kinematic wave model includes a description of infiltration with respect to time. If all the inputs to the kinematic wave model other than the infiltration characteristics are observed, the model may be used iteratively to estimate the infiltration characteristics based on coincidence between observed and predicted advance and runoff data. An example of this procedure using field data is shown. The results for this single example demonstrate that a wide range of infiltration parameters can lead to acceptable coincidence between the observed and predicted advance trajectory and outflow hydrograph. Fitting the advance trajectory and the outflow hydrograph simultaneously can result in a smaller solution space than fitting either singularly. For the example data set, small errors in inflow rate, surface roughness, or field slope had substantial effects on the infiltration parameters.