Reply to Comment by Roques et al. on “Base Flow Recession from Unsaturated-Saturated Porous Media considering Lateral Unsaturated Discharge and Aquifer Compressibility”

Liang，Xiuyu1; Zhan，Hongbin2; Zhang，You Kuan1; Schilling，Keith3

2018-04-01

Analytical methods Base flow recession Unsaturated-saturated flow

English

Roques et al. (, https://doi.org/10.1002/2017WR022085) claims that they have proposed an exponential time step (ETS) method to improve the computing method of Liang et al. (, https://doi.org/10.1002/2017WR020938) which used a constant time step (CTS) method on the derivative for dQ/dt in field data, where Q is the base flow discharge and t is the time since the start of base flow recession. This reply emphasizes that the main objective of Liang et al. (, https://doi.org/10.1002/2017WR020938) was to develop an analytical model to investigate the effects of the unsaturated flow on base flow recession, not on the data interpretation methods. The analytical model indicates that the base flow recession hydrograph behaves as dQ/dt ∼aQ with the exponent b close to 1 at late times, which is consistent with previous theoretical models. The model of Liang et al. (, https://doi.org/10.1002/2017WR020938) was applied to field data where the derivative of dQ/dt was computed using the CTS method, a method that has been widely adopted in previous studies. The ETS method proposed by Roques et al. (, https://doi.org/10.1016/j.advwatres.2017.07.013) appears to be a good alternative but its accuracy needs further validation. Using slopes to fit field data as proposed by Roques et al. (, https://doi.org/10.1002/2017WR022085) appears to match data satisfactorily at early times whereas it performs less satisfactorily at late times and leads to the exponent b being obviously larger than 1.

10.1002/2017WR022378

WATER RESOURCES RESEARCH

54

4

3220-3222

0043-1397

SCI

First ; Corresponding

2-s2.0-85044741701

Scopus

WOS:000434186400041

1944-7973

ENVIRONMENT/ECOLOGY

1.School of Environmental Science and Engineering,Southern University of Science and Technology,Shenzhen,China
2.Department of Geology & Geophysics,Texas A&M University,College Station,United States
3.Iowa Geological Survey,University of Iowa,Iowa City,United States

Liang，Xiuyu,Zhan，Hongbin,Zhang，You Kuan,等. Reply to Comment by Roques et al. on “Base Flow Recession from Unsaturated-Saturated Porous Media considering Lateral Unsaturated Discharge and Aquifer Compressibility”. 2018-04-01.