Comment on "Beach water table fluctuations due to wave run-up: Capillarity effects" by L. Li et al.

Abstract

Li et al.'s [1997] boundary condition for description of water table response under capillary effects is equivalent to Boulton's condition although in a different form. This leads one to address the area of potential hydrological applications of the model. In pumping tests the free surface is generally exposed to a monotonic head change, and the BNM boundary condition, considering monotonic time drawdown, is quite legitimate. However, simulation of periodic fluctuations in the water table would require an analysis that includes hysteresis, an effect that appears to have been neglected by Li et al.'s [1997]. Nevertheless, Li et al.'s [1997] results are important because they help to establish a link between the Boulton "effective" parameter and "physical" aquifer parameters for falling water table conditions, as it follows from the given explanation. Several problems for future research arise from the discussion: 1. Is the Li et al.'s [1997] condition on a moving boundary applicable for simulation of pumping tests in water table aquifers? 2. Are hysteretic effects in a capifiary fringe negligible in modeling of oscillatory water table movement? 3. Is the Boulton integral term in the kinematic condition on a moving boundary (together with the introduction of aquifer compressibility) an alternative (or improvement) to the Li et al.'s [1997] boundary condition? Analysis of field data on pumping tests in unconfined aquifers can be a benchmark problem to clarilS' these issues.