Comment on ''Base Flow Recession from Unsaturated-Saturated Porous Media considering Lateral Unsaturated Discharge and Aquifer Compressibility''

摘要

Liang et al. (2017) presented an analysis of the impacts of unsaturated zone processes on streamflow recession using methodology from Brutsaert and Nieber (1977) with a constant time step in computation of the time derivative of flow. Over the past 10 years, many authors have demonstrated that this method may produce artifacts that lead to incorrect interpretations. To demonstrate the impact of the choice of analysis methods, this comment presents an estimation of recession parameters using the Liang et al. (2017) discharge data that eliminates artifacts introduced through the constant time step. Here we use the exponential time step method, which revealed recession coefficient b greater than 1 which is inconsistent with the fitting framework used in Liang et al. (2017).