The coefficient ae and the exponentbe (also known as the baseflow coefficients) can
be derived using linear regression at log-log scale. Thebe value varies during the early to later
recession state, where ae represents a function
of the hydraulic characteristics controlled by factors including slope,
topography, drainage system density (Zecharias & Brutsaert, 1988),
aquifer thickness (Dewandel, Lachassagne, Bakalowicz, Weng, & Al-Malki,
2003), and hydraulic characteristics (Biswal & Marani, 2010), and
others. The recession constant above can be also expressed in the form
of the baseflow coefficients ae andbe (c =
1/[ae (2-be )],d= 2-be ). Related studies also made note of the
correlation between coefficient ae and catchment
drainage networks (Biswal & Marani, 2014; Shaw, 2016) and antecedent
groundwater storage (Patnaik, Biswal, Kumar, & Sivakumar, 2015; Bart &
Hope, 2014). Previous studies indicated recession parameters can
represent the physical characteristics of the resulting aquifers and the
structure of the river network and characterized catchment drainage
behaviors (i.e. drainage characteristic timescale and flow recession
rate (Brutsaert, 2008; Zhang, Chen, Hickel, & Shao, 2009; Troch et al.,
2013; van Tol & Lorentz, 2018; Dwivedi et al., 2019). It also used to
estimate hydraulic conductivity, drainable porosity, aquifer thickness,
and length of stream channels (Oyarzún et al., 2014; Arumí, Troch,
Maddock, Meixner, & Eastoe, 2016; Li, Zhang, Long, & Feng, 2017; Huang
& Yeh, 2019). To the purpose of this study, we regarded the results as
low-flow characteristics rather than defined the correlations with
related physical characteristics.
The recession process may also be affected by land cover (i.e.
vegetation coverage, vegetation types) and human activities (artificial
pumping, agricultural return flow, etc.). Therefore, the water balance
can be added an environmental impact during the recession period (Cheng
et al., 2017):